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Laine S, Sjöros T, Garthwaite T, Honka MJ, Löyttyniemi E, Eskola O, Saarenhovi M, Kallio P, Koivumäki M, Vähä-Ypyä H, Sievänen H, Vasankari T, Hirvonen J, Laitinen K, Houttu N, Kalliokoski K, Saunavaara V, Knuuti J, Heinonen IHA. Daily standing time, dietary fiber, and intake of unsaturated fatty acids are beneficially associated with hepatic insulin sensitivity in adults with metabolic syndrome. Front Endocrinol (Lausanne) 2024; 15:1272886. [PMID: 38989003 PMCID: PMC11233550 DOI: 10.3389/fendo.2024.1272886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Accepted: 06/11/2024] [Indexed: 07/12/2024] Open
Abstract
Background Obesity is associated with impaired glucose metabolism and hepatic insulin resistance. The aim was to investigate the associations of hepatic glucose uptake (HGU) and endogenous glucose production (EGP) to sedentary behavior (SB), physical activity (PA), cardiorespiratory fitness, dietary factors, and metabolic risk markers. Methods Forty-four adults with metabolic syndrome (mean age 58 [SD 7] years, BMI ranging from 25-40kg/; 25 females) were included. HGU was measured by positron emission tomography during the hyperinsulinemic-euglycemic clamp. EGP was calculated by subtracting the glucose infusion rate during clamp from the glucose rate of disappearance. SB and PA were measured with hip-worn accelerometers (26 [SD3] days). Fitness was assessed by maximal bicycle ergometry with respiratory gas measurements and dietary intake of nutrients by 4-day food diaries. Results HGU was not associated with fitness or any of the SB or PA measures. When adjusted for sex, age, and body fat-%, HGU was associated with whole-body insulin sensitivity (β=0.58), water-insoluble dietary fiber (β=0.29), energy percent (E%) of carbohydrates (β=-0.32), saccharose (β=-0.32), mono- and polyunsaturated fatty acids (β=0.35, β=0.41, respectively). EGP was associated with whole-body insulin sensitivity (β=-0.53), and low-density lipoprotein cholesterol [β=-0.31], and when further adjusted for accelerometry wear time, EGP was associated with standing [β=-0.43]. (p-value for all< 0.05). Conclusions Standing more, consuming a diet rich in fiber and unsaturated fatty acids, and a lower intake of carbohydrates, especially sugar, associate beneficially with hepatic insulin sensitivity. Habitual SB, PA, or fitness may not be the primary modulators of HGU and EGP. However, these associations need to be confirmed with intervention studies.
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Affiliation(s)
- Saara Laine
- Turku PET Centre, University of Turku, Åbo Akademi University and Turku University Hospital, Turku, Finland
| | - Tanja Sjöros
- Turku PET Centre, University of Turku, Åbo Akademi University and Turku University Hospital, Turku, Finland
| | - Taru Garthwaite
- Turku PET Centre, University of Turku, Åbo Akademi University and Turku University Hospital, Turku, Finland
| | - Miikka-Juhani Honka
- Turku PET Centre, University of Turku, Åbo Akademi University and Turku University Hospital, Turku, Finland
| | | | - Olli Eskola
- Turku PET Centre, University of Turku, Åbo Akademi University and Turku University Hospital, Turku, Finland
| | - Maria Saarenhovi
- Turku PET Centre, University of Turku, Åbo Akademi University and Turku University Hospital, Turku, Finland
- Department of Clinical Physiology and Nuclear Medicine, University of Turku and Turku University Hospital, Turku, Finland
| | - Petri Kallio
- Department of Clinical Physiology and Nuclear Medicine, University of Turku and Turku University Hospital, Turku, Finland
- Paavo Nurmi Center, University of Turku, Turku, Finland
| | - Mikko Koivumäki
- Turku PET Centre, University of Turku, Åbo Akademi University and Turku University Hospital, Turku, Finland
| | - Henri Vähä-Ypyä
- The UKK Institute for Health Promotion Research, Tampere, Finland
| | - Harri Sievänen
- The UKK Institute for Health Promotion Research, Tampere, Finland
| | - Tommi Vasankari
- The UKK Institute for Health Promotion Research, Tampere, Finland
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Jussi Hirvonen
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
- Department of Radiology, University of Turku and Turku University Hospital, Turku, Finland
| | - Kirsi Laitinen
- Institute of Biomedicine, University of Turku, Turku, Finland
| | - Noora Houttu
- Institute of Biomedicine, University of Turku, Turku, Finland
| | - Kari Kalliokoski
- Turku PET Centre, University of Turku, Åbo Akademi University and Turku University Hospital, Turku, Finland
| | - Virva Saunavaara
- Turku PET Centre, University of Turku, Åbo Akademi University and Turku University Hospital, Turku, Finland
- Department of Medical Physics, Division of Medical Imaging, Turku University Hospital, Turku, Finland
| | - Juhani Knuuti
- Turku PET Centre, University of Turku, Åbo Akademi University and Turku University Hospital, Turku, Finland
| | - Ilkka H A Heinonen
- Turku PET Centre, University of Turku, Åbo Akademi University and Turku University Hospital, Turku, Finland
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Eldor R, Francis BH, Fleming A, Neutel J, Homer K, Kidron M, Rosenstock J. Oral insulin (ORMD-0801) in type 2 diabetes mellitus: A dose-finding 12-week randomized placebo-controlled study. Diabetes Obes Metab 2023; 25:943-952. [PMID: 36281496 DOI: 10.1111/dom.14901] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 10/12/2022] [Accepted: 10/20/2022] [Indexed: 11/27/2022]
Abstract
AIMS To assess the safety and efficacy of multiple daily doses of oral insulin (ORMD-0801) in subjects with type 2 diabetes (T2DM) over 12 weeks. MATERIALS AND METHODS Participants with T2DM on metformin or combination oral therapy with glycated haemoglobin (HbA1c) levels ≥ 7.5% (58 mmol/mol) were randomized to receive ORMD-0801 8 mg or 16 mg once (QD) or twice (BID) daily, or 32 mg QD, BID or three times daily (TID) over a 12-week period. RESULTS A total of 373 subjects were randomized to active treatment or placebo (~60% male, age ~ 56 years, HbA1c 9%-9.8%; 75-84 mmol/mol). Placebo-adjusted HbA1c changes from baseline to Week 12 were observed with ORMD-0801 8 mg BID (-7.15 ± 3.57 mmol/mol [-0.65% ± 0.33%]; P = 0.046). However, a significant site interaction was observed in two sites. After excluding these, HbA1c reduction was observed with 8 mg QD (-0.81 ± 0.37%; -8.89 ± 4.01 mmol/mol; P = 0.028, n = 15), 8 mg BID (-0.82 ± 0.37%; -8.95 ± 4.08 mmol/mol; P = 0.029, n = 17), 32 mg QD (-0.54 ± 0.26%; -5.89 ± 2.78 mmol/mol;P = 0.036, n = 69) and 32 mg BID (-0.53 ± 0.26%; -5.80 ± 2.83 mmol/mol; P = 0.042, n = 68). No effect was observed with 16 mg QD (0.25 ± 0.37%; 2.76 ± 3.99 mmol/mol; P = 0.48, n = 18), 16 mg BID (-0.36 ± 0.40%; -3.97 ± P = 0.36, n = 15) or 32 mg TID (-0.45 ± 0.27%, -4.89 ± 2.90 mmol/mol; P = 0.093, n = 69). Continuous glucose monitor and serum glucose measurements showed similar trends but were not significant. ORMD-0801 was safe, well tolerated and not associated with weight gain or hypoglycaemia. CONCLUSIONS Oral insulin (ORMD-0801) induced greater reductions in HbA1c when compared to placebo, and was safe and well tolerated in individuals with uncontrolled T2DM. The efficacy and safety findings support continued development of the 8-mg dose at bedtime, which is currently being evaluated in two Phase 3 trials.
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Affiliation(s)
- Roy Eldor
- Diabetes Unit, Institute for Endocrinology, Metabolism and Hypertension, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel & Sackler Faculty of Medicine, Tel Aviv University, Tel-Aviv, Israel
| | | | | | - Joel Neutel
- Orange County Research Center, Tustin, California, USA
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Kraft G, Coate KC, Smith M, Farmer B, Scott M, Hastings J, Cherrington AD, Edgerton DS. Profound Sensitivity of the Liver to the Direct Effect of Insulin Allows Peripheral Insulin Delivery to Normalize Hepatic but Not Muscle Glucose Uptake in the Healthy Dog. Diabetes 2023; 72:196-209. [PMID: 36280227 PMCID: PMC9871195 DOI: 10.2337/db22-0471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Accepted: 10/18/2022] [Indexed: 01/28/2023]
Abstract
Endogenous insulin secretion is a key regulator of postprandial hepatic glucose metabolism, but this process is dysregulated in diabetes. Subcutaneous insulin delivery alters normal insulin distribution, causing relative hepatic insulin deficiency and peripheral hyperinsulinemia, a major risk factor for metabolic disease. Our aim was to determine whether insulin's direct effect on the liver is preeminent even when insulin is given into a peripheral vein. Postprandial-like conditions were created (hyperinsulinemia, hyperglycemia, and a positive portal vein to arterial glucose gradient) in healthy dogs. Peripheral (leg vein) insulin infusion elevated arterial and hepatic levels 8.0-fold and 2.8-fold, respectively. In one group, insulin's full effects were allowed. In another, insulin's indirect hepatic effects were blocked with the infusion of triglyceride, glucagon, and inhibitors of brain insulin action (intracerebroventricular) to prevent decreases in plasma free fatty acids and glucagon, while blocking increased hypothalamic insulin signaling. Despite peripheral insulin delivery the liver retained its full ability to store glucose, even when insulin's peripheral effects were blocked, whereas muscle glucose uptake markedly increased, creating an aberrant distribution of glucose disposal between liver and muscle. Thus, the healthy liver's striking sensitivity to direct insulin action can overcome the effect of relative hepatic insulin deficiency, whereas excess insulin in the periphery produces metabolic abnormalities in nonhepatic tissues.
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Affiliation(s)
| | | | | | | | | | | | | | - Dale S. Edgerton
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
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Adler GK, Hornik ES, Murray G, Bhandari S, Yadav Y, Heydarpour M, Basu R, Garg R, Tirosh A. Acute effects of the food preservative propionic acid on glucose metabolism in humans. BMJ Open Diabetes Res Care 2021; 9:9/1/e002336. [PMID: 34312159 PMCID: PMC8314753 DOI: 10.1136/bmjdrc-2021-002336] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Accepted: 06/30/2021] [Indexed: 11/03/2022] Open
Abstract
INTRODUCTION Propionic acid (PA) is a common food preservative generally recognized as safe by the US Food and Drug Administration; however, exogenous PA has effects on glucose metabolism that are not fully understood. Our preclinical studies demonstrated exogenous PA increases glucagon, norepinephrine, and endogenous glucose production (EGP). RESEARCH DESIGN AND METHODS We performed a randomized, placebo-controlled, crossover study in 28 healthy men and women to determine the effect of PA (1500 mg calcium propionate) on these factors. Subjects had two study visits, each preceded by a 1 week, PA-free diet. During each visit, glucose, insulin, glucagon, norepinephrine, epinephrine, and EGP were assessed for 2 hours after oral administration of PA/placebo under resting conditions (protocol 1) and during either a euglycemic (~85-90 mg/dL) or hypoglycemic (~65-70 mg/dL) hyperinsulinemic clamp (protocol 2). RESULTS PA, as compared with placebo, significantly increased: (1) glucagon and norepinephrine during protocol 1; (2) glucagon, norepinephrine, and epinephrine under euglycemic conditions in protocol 2; and (3) norepinephrine, epinephrine, and EGP under hypoglycemic conditions in protocol 2. CONCLUSION Oral consumption of PA leads to inappropriate activation of the insulin counterregulatory hormonal network. This inappropriate stimulation highlights PA as a potential metabolic disruptor.
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Affiliation(s)
- Gail K Adler
- Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Ezra S Hornik
- Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Gillian Murray
- Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Shreya Bhandari
- Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Yogesh Yadav
- Department of Medicine, University of Virginia, Charlottesville, Virginia, USA
| | - Mahyar Heydarpour
- Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Rita Basu
- Department of Medicine, University of Virginia, Charlottesville, Virginia, USA
| | - Rajesh Garg
- Department of Medicine, University of Miami Miller School of Medicine, Miami, Florida, USA
| | - Amir Tirosh
- Division of Endocrinology, Sheba Medical Center and Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel
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Kraft G, Coate KC, Smith M, Farmer B, Scott M, Cherrington AD, Edgerton DS. The Importance of the Mechanisms by Which Insulin Regulates Meal-Associated Liver Glucose Uptake in the Dog. Diabetes 2021; 70:1292-1302. [PMID: 33757993 PMCID: PMC8275892 DOI: 10.2337/db20-1271] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 03/18/2021] [Indexed: 12/17/2022]
Abstract
Hepatic glucose uptake (HGU) is critical for maintaining normal postprandial glucose metabolism. Insulin is clearly a key regulator of HGU, but the physiologic mechanisms by which it acts have yet to be established. This study sought to determine the mechanisms by which insulin regulates liver glucose uptake under postprandial-like conditions (hyperinsulinemia, hyperglycemia, and a positive portal vein-to-arterial glucose gradient). Portal vein insulin infusion increased hepatic insulin levels fivefold in healthy dogs. In one group (n = 7), the physiologic response was allowed to fully occur, while in another (n = 7), insulin's indirect hepatic effects, occurring secondary to its actions on adipose tissue, pancreas, and brain, were blocked. This was accomplished by infusing triglyceride (intravenous), glucagon (portal vein), and inhibitors of brain insulin action (intracerebroventricular) to prevent decreases in plasma free fatty acids or glucagon, while blocking increased hypothalamic insulin signaling for 4 h. In contrast to the indirect hepatic effects of insulin, which were previously shown capable of independently generating a half-maximal stimulation of HGU, direct hepatic insulin action was by itself able to fully stimulate HGU. This suggests that under hyperinsulinemic/hyperglycemic conditions insulin's indirect effects are redundant to direct engagement of hepatocyte insulin receptors.
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Affiliation(s)
- Guillaume Kraft
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
| | - Katie C Coate
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
| | - Marta Smith
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
| | - Ben Farmer
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
| | - Melanie Scott
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
| | - Alan D Cherrington
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
| | - Dale S Edgerton
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN
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Edgerton DS, Moore MC, Gregory JM, Kraft G, Cherrington AD. Importance of the route of insulin delivery to its control of glucose metabolism. Am J Physiol Endocrinol Metab 2021; 320:E891-E897. [PMID: 33813879 PMCID: PMC8238128 DOI: 10.1152/ajpendo.00628.2020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 03/24/2021] [Accepted: 03/26/2021] [Indexed: 12/12/2022]
Abstract
Pancreatic insulin secretion produces an insulin gradient at the liver compared with the rest of the body (approximately 3:1). This physiological distribution is lost when insulin is injected subcutaneously, causing impaired regulation of hepatic glucose production and whole body glucose uptake, as well as arterial hyperinsulinemia. Thus, the hepatoportal insulin gradient is essential to the normal control of glucose metabolism during both fasting and feeding. Insulin can regulate hepatic glucose production and uptake through multiple mechanisms, but its direct effects on the liver are dominant under physiological conditions. Given the complications associated with iatrogenic hyperinsulinemia in patients treated with insulin, insulin designed to preferentially target the liver may have therapeutic advantages.
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Affiliation(s)
- Dale S Edgerton
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Mary C Moore
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Justin M Gregory
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Guillaume Kraft
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Alan D Cherrington
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
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González F, Mather KJ, Considine RV, Abdelhadi OA, Acton AJ. Salicylate administration suppresses the inflammatory response to nutrients and improves ovarian function in polycystic ovary syndrome. Am J Physiol Endocrinol Metab 2020; 319:E744-E752. [PMID: 32830548 PMCID: PMC7750514 DOI: 10.1152/ajpendo.00228.2020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Oxidative stress (OS) and inflammation are often present in polycystic ovary syndrome (PCOS). We examined the effects of salsalate treatment on nutrient-induced OS and inflammation, ovarian androgen secretion, ovulation, and insulin sensitivity in PCOS. Eight lean insulin-sensitive women with PCOS and eight age- and body composition-matched ovulatory controls for baseline comparison participated in the study. The women with PCOS underwent a 12-wk treatment of salsalate, a nonsteroidal anti-inflammatory drug, at a dose of 3 g daily. Markers of OS and inflammation were quantified in mononuclear cells (MNC) and plasma from blood drawn fasting and 2 h after saturated fat ingestion before and after treatment. Ovarian androgen secretion was assessed from blood drawn fasting and 24, 48, and 72 h after human chorionic gonadotropin (HCG) administration before and after treatment. Ovulation was documented based on biphasic basal body temperatures and luteal range progesterone elevations. A two-step pancreatic clamp was performed pre- and posttreatment to measure basal endogenous glucose production (EGP) and the steady-state glucose disposal rate (GDR) during the euglycemic phase and markers of OS and inflammation in MNC and plasma during the hyperglycemic phase. Salsalate administration suppressed lipid- and glucose-stimulated reactive oxygen species generation, activated nuclear factor-κB and circulating tumor necrosis factor-α, normalized basal androgen levels, and lowered HCG-stimulated androgen secretion without altering EGP or GDR. Four salsalate-treated subjects responded with two consecutive ovulations. We conclude that in PCOS, salsalate-induced suppression of OS and inflammation ameliorates ovarian androgen hypersecretion and may induce ovulation while maintaining insulin action.
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Affiliation(s)
- Frank González
- Department of Obstetrics and Gynecology, University of Illinois at Chicago, College of Medicine, Chicago, Illinois
| | - Kieren J Mather
- Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana
| | - Robert V Considine
- Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana
| | - Ola A Abdelhadi
- Department of Obstetrics and Gynecology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Anthony J Acton
- Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana
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Romeres D, Olson K, Carter R, Cobelli C, Dalla Man C, Basu A, Basu R. Hyperglycemia But Not Hyperinsulinemia Is Favorable for Exercise in Type 1 Diabetes: A Pilot Study. Diabetes Care 2020; 43:2176-2182. [PMID: 32661106 PMCID: PMC7440891 DOI: 10.2337/dc20-0611] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Accepted: 06/09/2020] [Indexed: 02/03/2023]
Abstract
OBJECTIVE To distinguish the effects of hyperglycemia and hyperinsulinemia on exercise-induced increases in Rd and endogenous glucose production (EGP) in type 1 diabetes. RESEARCH DESIGN AND METHODS We studied six participants without diabetes and six participants with type 1 diabetes on three visits in random order for the following: euglycemia, low insulin (EuLoI); euglycemia, high insulin (EuHiI); and hyperglycemia, low insulin (HyLoI). Glucose fluxes were measured using [6,6-2H2] glucose before, during, and after 60 min of exercise. RESULTS Rd increased (P < 0.01) with exercise within groups, while peak Rd during exercise was lower (P < 0.01) in participants with type 1 diabetes than participants without diabetes during all visits. In type 1 diabetes participants, EGP increased (P < 0.001) with exercise during EuLoI and HyLoI but not during EuHiI. This demonstrates that hyperinsulinemia, but not hyperglycemia, blunts the compensatory exercise-induced increase in EGP in type 1 diabetes. CONCLUSIONS The data from this pilot study indicate that 1) exercise-induced compensatory increase in EGP was inhibited in participants with type 1 diabetes with hyperinsulinemia but not with hyperglycemia; 2) in contrast, in participants without diabetes, exercise-induced increase in EGP was inhibited only during combined hyperinsulinemia and hyperglycemia. Taken together, these results suggest that low insulin coupled with euglycemia or modest hyperglycemia appear to be the most favorable milieu for type 1 diabetes during exercise.
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Affiliation(s)
- Davide Romeres
- Department of Information Engineering, University of Padova, Padova, Italy
| | - Karen Olson
- Division of Endocrinology, Center of Diabetes Technology, University of Virginia School of Medicine, Charlottesville, VA
| | - Rickey Carter
- Department of Health Sciences Research, Mayo Clinic, Jacksonville, FL
| | - Claudio Cobelli
- Department of Information Engineering, University of Padova, Padova, Italy
| | - Chiara Dalla Man
- Department of Information Engineering, University of Padova, Padova, Italy
| | - Ananda Basu
- Division of Endocrinology, Center of Diabetes Technology, University of Virginia School of Medicine, Charlottesville, VA
| | - Rita Basu
- Division of Endocrinology, Center of Diabetes Technology, University of Virginia School of Medicine, Charlottesville, VA
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Basu A, Yadav Y, Carter RE, Basu R. Novel Insights Into Effects of Cortisol and Glucagon on Nocturnal Glucose Production in Type 2 Diabetes. J Clin Endocrinol Metab 2020; 105:5831336. [PMID: 32374825 PMCID: PMC7274493 DOI: 10.1210/clinem/dgaa241] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Accepted: 04/30/2020] [Indexed: 01/08/2023]
Abstract
CONTEXT The effect of physiological changes in night-time cortisol and glucagon on endogenous glucose production (EGP) and nocturnal glycemia are unknown. OBJECTIVE To determine the effects of changes in cortisol and glucagon on EGP during the night. DESIGN Two overnight protocols were conducted. In Protocol 1, endogenous cortisol was blocked with metyrapone and hydrocortisone infused either at constant (constant) or increasing (variable) rates to mimic basal or physiological nocturnal cortisol concentrations. In Protocol 2, endogenous glucagon was blocked with somatostatin and exogenous glucagon was infused at either basal or elevated rates to mimic nocturnal glucagon concentrations observed in nondiabetic (ND) and type 2 diabetes (T2D) individuals. EGP was measured using [3-3H] glucose and gluconeogenesis estimated with 2H2O in all studies. SETTING Mayo Clinic Clinical Research Trials Unit, Rochester, MN, US. PARTICIPANTS In Protocol 1, 34 subjects (17 ND and 17 T2D) and in Protocol 2, 39 subjects (21 ND and 18 T2D) were studied. MAIN OUTCOME MEASURES Endogenous glucose production. RESULTS EGP, gluconeogenesis, and glycogenolysis were higher with variable than with constant cortisol at 7 am in T2D subjects. In contrast, nocturnal EGP did not differ in ND subjects between variable and constant cortisol. While elevated glucagon increased EGP, glycogenolysis, and gluconeogenesis in ND, the data in T2D subjects indicated that EGP and gluconeogenesis but not glycogenolysis were higher during the early part of the night. CONCLUSION Nocturnal hyperglucagonemia, but not physiological rise in cortisol, contributes to nocturnal hyperglycemia in T2D due to increased gluconeogenesis.
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Affiliation(s)
- Ananda Basu
- Division of Endocrinology, University of Virginia School of Medicine, Charlottesville, VA, US
| | - Yogesh Yadav
- Division of Endocrinology, University of Virginia School of Medicine, Charlottesville, VA, US
| | - Rickey E Carter
- Department of Health Sciences Research, Mayo Clinic, Jacksonville, FL, US
| | - Rita Basu
- Division of Endocrinology, University of Virginia School of Medicine, Charlottesville, VA, US
- Correspondence and Reprint Requests: Rita Basu, MD, Professor of Medicine, Division of Endocrinology, Department of Medicine, Room 3108, 560 Ray C Hunt Drive, University of Virginia School of Medicine, Charlottesville, VA 22908. E-mail:
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Margolis LM, Wilson MA, Whitney CC, Carrigan CT, Murphy NE, Radcliffe PN, Gwin JA, Church DD, Wolfe RR, Ferrando AA, Young AJ, Pasiakos SM. Acute hypoxia reduces exogenous glucose oxidation, glucose turnover, and metabolic clearance rate during steady-state aerobic exercise. Metabolism 2020; 103:154030. [PMID: 31778707 DOI: 10.1016/j.metabol.2019.154030] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 10/30/2019] [Accepted: 11/25/2019] [Indexed: 12/21/2022]
Abstract
BACKGROUND Exogenous carbohydrate oxidation is lower during steady-state aerobic exercise in native lowlanders sojourning at high altitude (HA) compared to sea level (SL). However, the underlying mechanism contributing to reduction in exogenous carbohydrate oxidation during steady-state aerobic exercise performed at HA has not been explored. OBJECTIVE To determine if alterations in glucose rate of appearance (Ra), disappearance (Rd) and metabolic clearance rate (MCR) at HA provide a mechanism for explaining the observation of lower exogenous carbohydrate oxidation compared to during metabolically-matched, steady-state exercise at SL. METHODS Using a randomized, crossover design, native lowlanders (n = 8 males, mean ± SD, age: 23 ± 2 yr, body mass: 87 ± 10 kg, and VO2peak: SL 4.3 ± 0.2 L/min and HA 2.9 ± 0.2 L/min) consumed 145 g (1.8 g/min) of glucose while performing 80-min of metabolically-matched (SL: 1.66 ± 0.14 V̇O2 L/min 329 ± 28 kcal, HA: 1.59 ± 0.10 V̇O2 L/min, 320 ± 19 kcal) treadmill exercise in SL (757 mmHg) and HA (460 mmHg) conditions after a 5-h exposure. Substrate oxidation rates (g/min) and glucose turnover (mg/kg/min) during exercise were determined using indirect calorimetry and dual tracer technique (13C-glucose oral ingestion and [6,6-2H2]-glucose primed, continuous infusion). RESULTS Total carbohydrate oxidation was higher (P < 0.05) at HA (2.15 ± 0.32) compared to SL (1.39 ± 0.14). Exogenous glucose oxidation rate was lower (P < 0.05) at HA (0.35 ± 0.07) than SL (0.44 ± 0.05). Muscle glycogen oxidation was higher at HA (1.67 ± 0.26) compared to SL (0.83 ± 0.13). Total glucose Ra was lower (P < 0.05) at HA (12.3 ± 1.5) compared to SL (13.8 ± 2.0). Exogenous glucose Ra was lower (P < 0.05) at HA (8.9 ± 1.3) compared to SL (10.9 ± 2.2). Glucose Rd was lower (P < 0.05) at HA (12.7 ± 1.7) compared to SL (14.3 ± 2.0). MCR was lower (P < 0.05) at HA (9.0 ± 1.8) compared to SL (12.1 ± 2.3). Circulating glucose and insulin concentrations were higher in response carbohydrate intake during exercise at HA compared to SL. CONCLUSION Novel results from this investigation suggest that reductions in exogenous carbohydrate oxidation at HA may be multifactorial; however, the apparent insensitivity of peripheral tissue to glucose uptake may be a primary determinate.
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Affiliation(s)
- Lee M Margolis
- U.S. Army Research Institute of Environmental Medicine, Natick, MA, United States of America.
| | - Marques A Wilson
- U.S. Army Research Institute of Environmental Medicine, Natick, MA, United States of America
| | - Claire C Whitney
- U.S. Army Research Institute of Environmental Medicine, Natick, MA, United States of America
| | - Christopher T Carrigan
- U.S. Army Research Institute of Environmental Medicine, Natick, MA, United States of America
| | - Nancy E Murphy
- U.S. Army Research Institute of Environmental Medicine, Natick, MA, United States of America
| | - Patrick N Radcliffe
- U.S. Army Research Institute of Environmental Medicine, Natick, MA, United States of America; Oak Ridge Institute of Science and Education, Oak Ridge, TN, United States of America
| | - Jess A Gwin
- U.S. Army Research Institute of Environmental Medicine, Natick, MA, United States of America; Oak Ridge Institute of Science and Education, Oak Ridge, TN, United States of America
| | - David D Church
- Department of Geriatrics, Center for Translational Research in Aging and Longevity, Donald W. Reynolds Institute on Aging, University of Arkansas for Medical Sciences, Little Rock, AR, United States of America
| | - Robert R Wolfe
- Department of Geriatrics, Center for Translational Research in Aging and Longevity, Donald W. Reynolds Institute on Aging, University of Arkansas for Medical Sciences, Little Rock, AR, United States of America
| | - Arny A Ferrando
- Department of Geriatrics, Center for Translational Research in Aging and Longevity, Donald W. Reynolds Institute on Aging, University of Arkansas for Medical Sciences, Little Rock, AR, United States of America
| | - Andrew J Young
- U.S. Army Research Institute of Environmental Medicine, Natick, MA, United States of America; Oak Ridge Institute of Science and Education, Oak Ridge, TN, United States of America
| | - Stefan M Pasiakos
- U.S. Army Research Institute of Environmental Medicine, Natick, MA, United States of America
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11
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Warner SO, Yao MV, Cason RL, Winnick JJ. Exercise-Induced Improvements to Whole Body Glucose Metabolism in Type 2 Diabetes: The Essential Role of the Liver. Front Endocrinol (Lausanne) 2020; 11:567. [PMID: 32982968 PMCID: PMC7484211 DOI: 10.3389/fendo.2020.00567] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 07/13/2020] [Indexed: 01/22/2023] Open
Abstract
Type 2 diabetes (T2D) is a metabolic disease characterized by obesity, insulin resistance, and the dysfunction of several key glucoregulatory organs. Among these organs, impaired liver function is recognized as one of the earliest contributors to impaired whole-body glucose homeostasis, with well-characterized hepatic insulin resistance resulting in elevated rates of hepatic glucose production (HGP) and fasting hyperglycemia. One portion of this review will provide an overview of how HGP is regulated during the fasted state in healthy humans and how this process becomes dysregulated in patients with T2D. Less well-appreciated is the liver's role in post-prandial glucose metabolism, where it takes up and metabolizes one-third of orally ingested glucose. An abundance of literature has shown that the process of hepatic glucose uptake is impaired in patients with T2D, thereby contributing to glucose intolerance. A second portion of this review will outline how hepatic glucose uptake is regulated during the post-prandial state, and how it becomes dysfunctional in patients with T2D. Finally, it is well-known that exercise training has an insulin-sensitizing effect on the liver, which contributes to improved whole-body glucose metabolism in patients with T2D, thereby making it a cornerstone in the management of the disease. To this end, the impact of exercise on hepatic glucose metabolism will be thoroughly discussed, referencing key findings in the literature. At the same time, sources of heterogeneity that contribute to inconsistent findings in the field will be pointed out, as will important topics for future investigation.
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Affiliation(s)
- Shana O. Warner
- Division of Endocrinology, Diabetes and Metabolism, Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, OH, United States
| | - Michael V. Yao
- Division of Endocrinology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States
| | - Rebecca L. Cason
- Division of Endocrinology, Diabetes and Metabolism, Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, OH, United States
| | - Jason J. Winnick
- Division of Endocrinology, Diabetes and Metabolism, Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, OH, United States
- *Correspondence: Jason J. Winnick
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12
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Castriota F, Rieswijk L, Dahlberg S, La Merrill MA, Steinmaus C, Smith MT, Wang JC. A State-of-the-Science Review of Arsenic's Effects on Glucose Homeostasis in Experimental Models. ENVIRONMENTAL HEALTH PERSPECTIVES 2020; 128:16001. [PMID: 31898917 PMCID: PMC7015542 DOI: 10.1289/ehp4517] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Revised: 11/22/2019] [Accepted: 11/26/2019] [Indexed: 05/04/2023]
Abstract
BACKGROUND The prevalence of type 2 diabetes (T2D) has more than doubled since 1980. Poor nutrition, sedentary lifestyle, and obesity are among the primary risk factors. While an estimated 70% of cases are attributed to excess adiposity, there is an increased interest in understanding the contribution of environmental agents to diabetes causation and severity. Arsenic is one of these environmental chemicals, with multiple epidemiology studies supporting its association with T2D. Despite extensive research, the molecular mechanism by which arsenic exerts its diabetogenic effects remains unclear. OBJECTIVES We conducted a literature search focused on arsenite exposure in vivo and in vitro, using relevant end points to elucidate potential mechanisms of oral arsenic exposure and diabetes development. METHODS We explored experimental results for potential mechanisms and elucidated the distinct effects that occur at high vs. low exposure. We also performed network analyses relying on publicly available data, which supported our key findings. RESULTS While several mechanisms may be involved, our findings support that arsenite has effects on whole-body glucose homeostasis, insulin-stimulated glucose uptake, glucose-stimulated insulin secretion, hepatic glucose metabolism, and both adipose and pancreatic β -cell dysfunction. DISCUSSION This review applies state-of-the-science approaches to identify the current knowledge gaps in our understanding of arsenite on diabetes development. https://doi.org/10.1289/EHP4517.
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Affiliation(s)
- Felicia Castriota
- Superfund Research Program, University of California, Berkeley, California, USA
| | - Linda Rieswijk
- Superfund Research Program, University of California, Berkeley, California, USA
| | - Sarah Dahlberg
- Superfund Research Program, University of California, Berkeley, California, USA
| | - Michele A. La Merrill
- Department of Environmental Toxicology, University of California, Davis, California, USA
| | - Craig Steinmaus
- Superfund Research Program, University of California, Berkeley, California, USA
| | - Martyn T. Smith
- Superfund Research Program, University of California, Berkeley, California, USA
| | - Jen-Chywan Wang
- Superfund Research Program, University of California, Berkeley, California, USA
- Department of Nutritional Sciences & Toxicology, University of California, Berkeley, California, USA
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13
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De Gaetano A, Hardy TA. A novel fast-slow model of diabetes progression: Insights into mechanisms of response to the interventions in the Diabetes Prevention Program. PLoS One 2019; 14:e0222833. [PMID: 31600232 PMCID: PMC6786566 DOI: 10.1371/journal.pone.0222833] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Accepted: 09/09/2019] [Indexed: 12/22/2022] Open
Abstract
Several models for the long-term development of T2DM already exist, focusing on the dynamics of the interaction between glycemia, insulinemia and β-cell mass. Current models consider representative (fasting or daily average) glycemia and insulinemia as characterizing the compensation state of the subject at some instant in slow time. This implies that only these representative levels can be followed through time and that the role of fast glycemic oscillations is neglected. An improved model (DPM15) for the long-term progression of T2DM is proposed, introducing separate peripheral and hepatic (liver and kidney) insulin actions. The DPM15 model no longer uses near-equilibrium approximation to separate fast and slow time scales, but rather describes, at each step in slow time, a complete day in the life of the virtual subject in fast time. The model can thus represent both fasting and postprandial glycemic levels and describe the effect of interventions acting on insulin-enhanced tissue glucose disposal or on insulin-inhibited hepatic glucose output, as well as on insulin secretion and β-cell replicating ability. The model can simulate long-term variations of commonly used clinical indices (HOMA-B, HOMA-IR, insulinogenic index) as well as of Oral Glucose Tolerance or Euglycemic Hyperinsulinemic Clamp test results. The model has been calibrated against observational data from the Diabetes Prevention Program study: it shows good adaptation to observations as a function of very plausible values of the parameters describing the effect of such interventions as Placebo, Intensive LifeStyle and Metformin administration.
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Affiliation(s)
- Andrea De Gaetano
- CNR-IASI BioMatLab (Italian National Research Council - Institute of Analysis, Systems and Computer Science - Biomathematics Laboratory), Rome, Italy
| | - Thomas Andrew Hardy
- Lilly Research Laboratories, Eli Lilly and Company, Lilly Corporate Center, Indianapolis, Indiana, United States of America
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14
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Gregory JM, Muldowney JA, Engelhardt BG, Tyree R, Marks-Shulman P, Silver HJ, Donahue EP, Edgerton DS, Winnick JJ. Aerobic exercise training improves hepatic and muscle insulin sensitivity, but reduces splanchnic glucose uptake in obese humans with type 2 diabetes. Nutr Diabetes 2019; 9:25. [PMID: 31474750 PMCID: PMC6717736 DOI: 10.1038/s41387-019-0090-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Accepted: 07/30/2019] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Aerobic exercise training is known to have beneficial effects on whole-body glucose metabolism in people with type 2 diabetes (T2D). The responses of the liver to such training are less well understood. The purpose of this study was to determine the effect of aerobic exercise training on splanchnic glucose uptake (SGU) and insulin-mediated suppression of endogenous glucose production (EGP) in obese subjects with T2D. METHODS Participants included 11 obese humans with T2D, who underwent 15 ± 2 weeks of aerobic exercise training (AEX; n = 6) or remained sedentary for 15 ± 1 weeks (SED; n = 5). After an initial screening visit, each subject underwent an oral glucose load clamp and an isoglycemic/two-step (20 and 40 mU/m2/min) hyperinsulinemic clamp (ISO-clamp) to assess SGU and insulin-mediated suppression of EGP, respectively. After the intervention period, both tests were repeated. RESULTS In AEX, the ability of insulin to suppress EGP was improved during both the low (69 ± 9 and 80 ± 6% suppression; pre-post, respectively; p < 0.05) and high (67 ± 6 and 82 ± 4% suppression, respectively; p < 0.05) insulin infusion periods. Despite markedly improved muscle insulin sensitivity, SGU was reduced in AEX after training (22.9 ± 3.3 and 9.1 ± 6.0 g pre-post in AEX, respectively; p < 0.05). CONCLUSIONS In obese T2D subjects, exercise training improves whole-body glucose metabolism, in part, by improving insulin-mediated suppression of EGP and enhancing muscle glucose uptake, which occur despite reduced SGU during an oral glucose challenge.
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Affiliation(s)
- Justin M Gregory
- Ian M. Burr Division of Pediatric Endocrinology and Diabetes, Vanderbilt University School of Medicine, 1500 21st Ave, Suite 1514, Nashville, TN, 37212, USA
| | - James A Muldowney
- Division of Cardiovascular Medicine, Vanderbilt University School of Medicine, 2215 Garland Avenue, Nashville, TN, 37232-6015, USA
| | - Brian G Engelhardt
- Division of Hematology and Oncology, Vanderbilt University School of Medicine, 2215 Garland Avenue, Nashville, TN, 37232-6015, USA
| | - Regina Tyree
- Center for Human Nutrition, Vanderbilt University School of Medicine, 2215 Garland Avenue, Nashville, TN, 37232-6015, USA
| | - Pam Marks-Shulman
- Section of Surgical Sciences, Vanderbilt University School of Medicine, 2215 Garland Avenue, Nashville, TN, 37232-6015, USA
| | - Heidi J Silver
- Center for Human Nutrition, Vanderbilt University School of Medicine, 2215 Garland Avenue, Nashville, TN, 37232-6015, USA
| | - E Patrick Donahue
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, 2215 Garland Avenue, Nashville, TN, 37232-6015, USA
| | - Dale S Edgerton
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, 2215 Garland Avenue, Nashville, TN, 37232-6015, USA
| | - Jason J Winnick
- Division of Endocrinology, Diabetes and Metabolism, Department of Internal Medicine, University of Cincinnati College of Medicine, 231 Albert Sabin Way, Cincinnati, OH, 45267-0547, USA.
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15
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Edgerton DS, Scott M, Farmer B, Williams PE, Madsen P, Kjeldsen T, Brand CL, Fledelius C, Nishimura E, Cherrington AD. Targeting insulin to the liver corrects defects in glucose metabolism caused by peripheral insulin delivery. JCI Insight 2019; 5:126974. [PMID: 30830873 DOI: 10.1172/jci.insight.126974] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Peripheral hyperinsulinemia resulting from subcutaneous insulin injection is associated with metabolic defects which include abnormal glucose metabolism. The first aim of this study was to quantify the impairments in liver and muscle glucose metabolism that occur when insulin is delivered via a peripheral vein compared to when it is given through its endogenous secretory route (the hepatic portal vein) in overnight fasted conscious dogs. The second aim was to determine if peripheral delivery of a hepato-preferential insulin analog could restore the physiologic response to insulin that occurs under meal feeding conditions. This study is the first to show that hepatic glucose uptake correlates with insulin's direct effects on the liver under hyperinsulinemic-hyperglycemic conditions. In addition, glucose uptake was equally divided between the liver and muscle when insulin was infused into the portal vein, but when it was delivered into a peripheral vein the percentage of glucose taken up by muscle was 4-times greater than that going to the liver, with liver glucose uptake being less than half of normal. These defects could not be corrected by adjusting the dose of peripheral insulin. On the other hand, hepatic and non-hepatic glucose metabolism could be fully normalized by a hepato-preferential insulin analog.
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Affiliation(s)
- Dale S Edgerton
- Vanderbilt University School of Medicine, Department of Molecular Physiology and Biophysics, Nashville, Tennessee, USA
| | - Melanie Scott
- Vanderbilt University School of Medicine, Department of Molecular Physiology and Biophysics, Nashville, Tennessee, USA
| | - Ben Farmer
- Vanderbilt University School of Medicine, Department of Molecular Physiology and Biophysics, Nashville, Tennessee, USA
| | - Phillip E Williams
- Vanderbilt University Medical Center, Division of Surgical Research, Nashville, Tennessee, USA
| | - Peter Madsen
- Research and Development, Novo Nordisk A/S, Novo Nordisk Park, Maaleov, Denmark
| | - Thomas Kjeldsen
- Research and Development, Novo Nordisk A/S, Novo Nordisk Park, Maaleov, Denmark
| | - Christian L Brand
- Research and Development, Novo Nordisk A/S, Novo Nordisk Park, Maaleov, Denmark
| | - Christian Fledelius
- Research and Development, Novo Nordisk A/S, Novo Nordisk Park, Maaleov, Denmark
| | - Erica Nishimura
- Research and Development, Novo Nordisk A/S, Novo Nordisk Park, Maaleov, Denmark
| | - Alan D Cherrington
- Vanderbilt University School of Medicine, Department of Molecular Physiology and Biophysics, Nashville, Tennessee, USA
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16
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Cree-Green M, Wiromrat P, Stuppy JJ, Thurston J, Bergman BC, Baumgartner AD, Bacon S, Scherzinger A, Pyle L, Nadeau KJ. Youth with type 2 diabetes have hepatic, peripheral, and adipose insulin resistance. Am J Physiol Endocrinol Metab 2019; 316:E186-E195. [PMID: 30562061 PMCID: PMC6397366 DOI: 10.1152/ajpendo.00258.2018] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Adolescents with type 2 diabetes (T2D) have severe insulin resistance (IR) secondary to obesity, genetics, and puberty, and IR predicts metabolic comorbidities. Adults with T2D have multitissue IR, which has guided therapeutic developments, but this is not established in youth. We sought to assess adipose, hepatic, and peripheral insulin sensitivity in adolescents with and without T2D. Twenty-seven youth with T2D [age: 15.6 ± 0.4 yr; female: 78%; body mass index (BMI) percentile: 96.1 (52.6, 95.9), late puberty; hemoglobin A1c (HbA1c) 7.3% (6.2, 10.1)] and 21 controls of similar BMI, pubertal stage, and habitual activity were enrolled. Insulin action was measured with a four-phase hyperinsulinemic-euglycemic clamp (basal, 10, 16, and 80 mU·m-2·min-1 for studying adipose, hepatic, and peripheral IR, respectively) with glucose and glycerol isotope tracers. Total fat mass, fat-free mass, liver fat fraction, and visceral fat were measured with dual-energy x-ray absorptiometry (DXA) and MRI, respectively. Free fatty acids (FFAs), lipid profile, and inflammatory markers were also measured. Adolescents with T2D had higher lipolysis ( P = 0.012), endogenous glucose production ( P < 0.0001), and lower glucose clearance ( P = 0.002) during hyperinsulinemia than controls. In T2D, peripheral IR positively correlated to FFA ( P < 0.001), inflammatory markers, visceral ( P = 0.004) and hepatic fat ( P = 0.007); hepatic IR correlated with central obesity ( P = 0.004) and adipose IR ( P = 0.003). Youth with T2D have profound multitissue IR compared with BMI-equivalent youth without T2D. The development of multitissue interactions appears crucial to the pathogenesis of T2D. Therapeutic targets on multitissue IR may be of benefit, deserving of further research.
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Affiliation(s)
- Melanie Cree-Green
- Department of Pediatrics, Division of Pediatric Endocrinology, University of Colorado Anschutz Medical Campus , Aurora, Colorado
- Barbara Davis Center for Childhood Diabetes, University of Colorado Anschutz Medical Campus , Aurora, Colorado
| | - Pattara Wiromrat
- Department of Pediatrics, Division of Pediatric Endocrinology, University of Colorado Anschutz Medical Campus , Aurora, Colorado
| | - Jacob J Stuppy
- Department of Pediatrics, Division of Pediatric Endocrinology, University of Colorado Anschutz Medical Campus , Aurora, Colorado
- Department of Biomedical Sciences and Biotechnology, University of Colorado Anschutz Medical Campus , Aurora, Colorado
| | - Jessica Thurston
- Department of Biostatistics and Informatics, Colorado School of Public Health , Aurora, Colorado
| | - Bryan C Bergman
- Department of Medicine, Division of Endocrinology, University of Colorado Anschutz Medical Campus , Aurora, Colorado
| | - Amy D Baumgartner
- Department of Pediatrics, Division of Pediatric Endocrinology, University of Colorado Anschutz Medical Campus , Aurora, Colorado
| | - Samantha Bacon
- Department of Medicine, Division of Endocrinology, University of Colorado Anschutz Medical Campus , Aurora, Colorado
| | - Ann Scherzinger
- Department of Radiology, University of Colorado Anschutz Medical Campus , Aurora, Colorado
| | - Laura Pyle
- Department of Biostatistics and Informatics, Colorado School of Public Health , Aurora, Colorado
- Department of Pediatrics, University of Colorado Anschutz Medical Campus , Aurora, Colorado
| | - Kristen J Nadeau
- Department of Pediatrics, Division of Pediatric Endocrinology, University of Colorado Anschutz Medical Campus , Aurora, Colorado
- Barbara Davis Center for Childhood Diabetes, University of Colorado Anschutz Medical Campus , Aurora, Colorado
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17
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Pathophysiological mechanisms of diabetic cardiomyopathy and the therapeutic potential of epigallocatechin-3-gallate. Biomed Pharmacother 2018; 109:2155-2172. [PMID: 30551473 DOI: 10.1016/j.biopha.2018.11.086] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2018] [Revised: 11/14/2018] [Accepted: 11/20/2018] [Indexed: 12/26/2022] Open
Abstract
Cardiovascular complications are considered one of the leading causes of morbidity and mortality among diabetic patients. Diabetic cardiomyopathy (DCM) is a type of cardiovascular damage presents in diabetic patients independent of the coexistence of ischemic heart disease or hypertension. It is characterized by impaired diastolic relaxation time, myocardial dilatation and hypertrophy and reduced systolic and diastolic functions of the left ventricle. Molecular mechanisms underlying these pathological changes in the diabetic heart are most likely multifactorial and include, but not limited to, oxidative/nitrosative stress, increased advanced glycation end products, mitochondrial dysfunction, inflammation and cell death. The aim of this review is to address the major molecular mechanisms implicated in the pathogenesis of DCM. In addition, this review provides studies conducted to determine the pharmacological effects of (-)-epigallocatechin-3-gallate (EGCG), the major polyphenol in green tea, focusing on its therapeutic potential against the processes involved in the pathogenesis and progression of DCM. EGCG has been shown to exert several potential therapeutic properties both in vitro and in vivo. Given its therapeutic potential, EGCG might be a promising drug candidate to decrease the morbidity and mortality associated with DCM and other diabetes complications.
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18
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Basu A, Joshi N, Miles J, Carter RE, Rizza RA, Basu R. Paradigm Shifts in Nocturnal Glucose Control in Type 2 Diabetes. J Clin Endocrinol Metab 2018; 103:3801-3809. [PMID: 30020503 PMCID: PMC6179178 DOI: 10.1210/jc.2018-00873] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Accepted: 06/27/2018] [Indexed: 01/17/2023]
Abstract
CONTEXT A better understanding of nocturnal regulation of glucose homeostasis will provide the framework for designing rational therapeutic strategies to improve the management of overnight glucose in patients with type 2 diabetes (T2D). OBJECTIVE To establish the nocturnal pattern and regulation of glucose production (EGP) in humans and to determine whether the pattern is dysregulated in people with T2D. DESIGN Subjects were infused with [3-3H] glucose overnight. Arterial blood samples were drawn for hormones and analytes to estimate EGP throughout the night. Deuterium-labeled water was provided to measure gluconeogenesis (GNG) using the hexamethylenetetramine method of Landau. SETTING Mayo Clinic Clinical Research Trials Unit, Rochester, MN, USA. PARTICIPANTS AND INTERVENTIONS A total of 43 subjects [23 subjects with T2D and 20 nondiabetic (ND) subjects comparable for age and body mass index] were included in this study. MAIN OUTCOME(S) MEASURE(S) Glucose and EGP. RESULTS Plasma glucose, C-peptide, and glucagon concentrations were higher throughout the night, whereas insulin concentrations were higher in subjects with T2D vs ND subjects at 1:00 and 4:00 am but similar at 7:00 am. EGP was higher in the subjects with T2D than in the ND subjects throughout the night (P < 0.001). Glycogenolysis (GGL) fell and GNG rose, resulting in significantly higher (P < 0.001) rates of GNG at 4:00 and 7:00 am and significantly (P < 0.001) higher rates of GGL at 1:00, 4:00, and 7:00 am in T2D as compared with ND. CONCLUSIONS These data imply that optimal therapies for T2D for nocturnal/fasting glucose control should target not only the absolute rates of EGP but also the contributing pathways of GGL and GNG sequentially.
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Affiliation(s)
- Ananda Basu
- Department of Endocrinology, University of Virginia School of Medicine, Charlottesville, Virginia
| | - Nisha Joshi
- Endocrine Research Unit, Mayo Clinic, Rochester, Minnesota
| | - John Miles
- Division of Endocrinology, Metabolism and Genetics, University of Kansas Medical Center, Kansas City, Kansas
| | - Rickey E Carter
- Department of Health Sciences Research, Mayo Clinic, Jacksonville, Florida
| | - Robert A Rizza
- Endocrine Research Unit, Mayo Clinic, Rochester, Minnesota
| | - Rita Basu
- Department of Endocrinology, University of Virginia School of Medicine, Charlottesville, Virginia
- Correspondence and Reprint Requests: Rita Basu, MD, Department of Endocrinology, Center for Diabetes Technology, University of Virginia School of Medicine, Room 3108, 560 Ray C. Hunt Drive, Charlottesville, Virginia 22908. E-mail:
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19
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Matsuba I, Matsuba R, Ishibashi S, Yamashita S, Arai H, Yokote K, Suganami H, Araki E. Effects of a novel selective peroxisome proliferator-activated receptor-α modulator, pemafibrate, on hepatic and peripheral glucose uptake in patients with hypertriglyceridemia and insulin resistance. J Diabetes Investig 2018; 9:1323-1332. [PMID: 29603684 PMCID: PMC6215940 DOI: 10.1111/jdi.12845] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 01/17/2018] [Accepted: 03/21/2018] [Indexed: 12/20/2022] Open
Abstract
AIMS/INTRODUCTION Pemafibrate is a novel selective peroxisome proliferator-activated receptor-α modulator with potent triglyceride-lowering and high-density lipoprotein cholesterol-raising effects. We showed that pemafibrate decreased the homeostatic model assessment for insulin resistance in patients with dyslipidemia. To investigate how pemafibrate improves insulin sensitivity, we used a hyperinsulinemic-euglycemic clamp technique to determine the splanchnic and peripheral glucose uptake in patients with hypertriglyceridemia and insulin resistance. MATERIALS AND METHODS A total of 27 patients with hypertriglyceridemia and insulin resistance were randomly assigned to receive pemafibrate (0.4 mg/day, b.i.d.) or placebo treatment for 12 weeks. The hyperinsulinemic-euglycemic clamp test combined with oral glucose loading was carried out at weeks 0 and 12 to evaluate the splanchnic and peripheral glucose uptake. RESULTS Pemafibrate, but not the placebo, significantly increased the splanchnic glucose uptake rate from baseline (19.6 ± 5.9% with P = 0.005 and 2.1 ± 7.4% with P = 0.78, respectively), although no significant difference between the groups was observed (P = 0.084). Conversely, peripheral glucose uptake rate was not significantly altered. Pemafibrate, compared with the placebo, significantly decreased plasma triglycerides (-61.4 ± 16.4% vs -2.5 ± 41.4%, P = 0.001), free fatty acids (-24.8 ± 23.2% vs 2.0 ± 26.8%, P = 0.016) and gamma-glutamyl transpeptidase (-30 ± 46 vs 10 ± 19 U/L, P = 0.009) levels, and significantly increased fibroblast growth factor 21 (457.7 ± 402.1 vs -41.7 ± 37.4 pg/mL, P = 0.007) levels. CONCLUSIONS Pemafibrate increased splanchnic glucose uptake from baseline in patients with hypertriglyceridemia.
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Affiliation(s)
| | - Ren Matsuba
- Department of Internal Medicine, Division of Metabolism and Endocrinology, St. Marianna University School of Medicine, Kanagawa, Japan
| | - Shun Ishibashi
- Division of Endocrinology and Metabolism, Department of Medicine, Jichi Medical University, Tochigi, Japan
| | - Shizuya Yamashita
- Department of Community Medicine and Department of Cardiovascular Medicine, Osaka University Graduate School of Medicine, Osaka, Japan.,Rinku General Medical Center, Osaka, Japan
| | - Hidenori Arai
- National Center for Geriatrics and Gerontology, Aichi, Japan
| | - Koutaro Yokote
- Department of Clinical Cell Biology and Medicine, Chiba University Graduate School of Medicine, Chiba, Japan
| | - Hideki Suganami
- Clinical Data Science Department, Kowa Company, Ltd., Tokyo, Japan
| | - Eiichi Araki
- Department of Metabolic Medicine, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
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20
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Kowalski GM, Moore SM, Hamley S, Selathurai A, Bruce CR. The Effect of Ingested Glucose Dose on the Suppression of Endogenous Glucose Production in Humans. Diabetes 2017; 66:2400-2406. [PMID: 28684634 DOI: 10.2337/db17-0433] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Accepted: 06/21/2017] [Indexed: 11/13/2022]
Abstract
Insulin clamp studies have shown that the suppressive actions of insulin on endogenous glucose production (EGP) are markedly more sensitive than for stimulating glucose disposal (Rd). However, clamp conditions do not adequately mimic postprandial physiological responses. Here, using the variable infusion dual-tracer approach, we used a threefold range of ingested glucose doses (25, 50, and 75 g) to investigate how physiological changes in plasma insulin influence EGP in healthy subjects. Remarkably, the glucose responses were similar for all doses tested, yet there was a dose-dependent increase in insulin secretion and plasma insulin levels. Nonetheless, EGP was suppressed with the same rapidity and magnitude (∼55%) across all doses. The progressive hyperinsulinemia, however, caused a dose-dependent increase in the estimated rates of Rd, which likely accounts for the lack of a dose effect on plasma glucose excursions. This suggests that after glucose ingestion, the body preferentially permits a transient and optimal degree of postprandial hyperglycemia to efficiently enhance insulin-induced changes in glucose fluxes, thereby minimizing the demand for insulin secretion. This may represent an evolutionarily conserved mechanism that not only reduces the secretory burden on β-cells but also avoids the potential negative consequences of excessive insulin release into the systemic arterial circulation.
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Affiliation(s)
- Greg M Kowalski
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Science, Deakin University, Burwood, Victoria, Australia
| | - Samantha M Moore
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Science, Deakin University, Burwood, Victoria, Australia
| | - Steven Hamley
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Science, Deakin University, Burwood, Victoria, Australia
| | - Ahrathy Selathurai
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Science, Deakin University, Burwood, Victoria, Australia
| | - Clinton R Bruce
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Science, Deakin University, Burwood, Victoria, Australia
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21
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Abstract
Insulin remains indispensable to the treatment of diabetes, but its availability in injectable form only has hampered its timely and broader use. The development of an oral insulin remains an ultimate goal to both enhance ease of use, and to provide therapeutic advantages rooted in its direct delivery to the portal vein and liver. By mimicking the physiological path taken by pancreatic insulin, oral insulin is expected to have a distinct effect on the hepatic aspect of carbohydrate metabolism, hepatic insulin resistance, and, at the same time, avoid hyperinsulinemia and minimize the risk of hypoglycemia. With oral insulin approaching late stages of development, the goal of this review is to examine oral insulin in a physiological context and report on recent progress in its development.
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Affiliation(s)
- Ehud Arbit
- Oramed Pharmaceuticals, Inc. Jerusalem, Israel
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22
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Miller C, Pachanski MJ, Kirkland ME, Kosinski DT, Mane J, Bunzel M, Cao J, Souza S, Thomas-Fowlkes B, Di Salvo J, Weinglass AB, Li X, Myers RW, Knagge K, Carrington PE, Hagmann WK, Trujillo ME. GPR40 partial agonist MK-2305 lower fasting glucose in the Goto Kakizaki rat via suppression of endogenous glucose production. PLoS One 2017; 12:e0176182. [PMID: 28542610 PMCID: PMC5441580 DOI: 10.1371/journal.pone.0176182] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Accepted: 04/06/2017] [Indexed: 11/19/2022] Open
Abstract
GPR40 (FFA1) is a fatty acid receptor whose activation results in potent glucose lowering and insulinotropic effects in vivo. Several reports illustrate that GPR40 agonists exert glucose lowering in diabetic humans. To assess the mechanisms by which GPR40 partial agonists improve glucose homeostasis, we evaluated the effects of MK-2305, a potent and selective partial GPR40 agonist, in diabetic Goto Kakizaki rats. MK-2305 decreased fasting glucose after acute and chronic treatment. MK-2305-mediated changes in glucose were coupled with increases in plasma insulin during hyperglycemia and glucose challenges but not during fasting, when glucose was normalized. To determine the mechanism(s) mediating these changes in glucose metabolism, we measured the absolute contribution of precursors to glucose production in the presence or absence of MK-2305. MK-2305 treatment resulted in decreased endogenous glucose production (EGP) driven primarily through changes in gluconeogenesis from substrates entering at the TCA cycle. The decrease in EGP was not likely due to a direct effect on the liver, as isolated perfused liver studies showed no effect of MK-2305 ex vivo and GPR40 is not expressed in the liver. Taken together, our results suggest MK-2305 treatment increases glucose stimulated insulin secretion (GSIS), resulting in changes to hepatic substrate handling that improve glucose homeostasis in the diabetic state. Importantly, these data extend our understanding of the underlying mechanisms by which GPR40 partial agonists reduce hyperglycemia.
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Affiliation(s)
- Corin Miller
- Departments of Translational Imaging Biomarkers, Merck & Co., Inc., Kenilworth, New Jersey, United States of America
| | - Michele J. Pachanski
- In Vivo Pharmacology, Merck & Co., Inc., Kenilworth, New Jersey, United States of America
| | - Melissa E. Kirkland
- In Vivo Pharmacology, Merck & Co., Inc., Kenilworth, New Jersey, United States of America
| | - Daniel T. Kosinski
- In Vivo Pharmacology, Merck & Co., Inc., Kenilworth, New Jersey, United States of America
| | - Joel Mane
- In Vivo Pharmacology, Merck & Co., Inc., Kenilworth, New Jersey, United States of America
| | - Michelle Bunzel
- Departments of Translational Imaging Biomarkers, Merck & Co., Inc., Kenilworth, New Jersey, United States of America
| | - Jin Cao
- Departments of Translational Imaging Biomarkers, Merck & Co., Inc., Kenilworth, New Jersey, United States of America
| | - Sarah Souza
- In Vitro Pharmacology, Merck & Co., Inc., Kenilworth, New Jersey, United States of America
| | - Brande Thomas-Fowlkes
- In Vitro Pharmacology, Merck & Co., Inc., Kenilworth, New Jersey, United States of America
| | - Jerry Di Salvo
- In Vitro Pharmacology, Merck & Co., Inc., Kenilworth, New Jersey, United States of America
| | - Adam B. Weinglass
- In Vitro Pharmacology, Merck & Co., Inc., Kenilworth, New Jersey, United States of America
| | - Xiaoyan Li
- Cardio-Metabolic Diseases, Merck & Co., Inc., Kenilworth, New Jersey, United States of America
| | - Robert W. Myers
- In Vitro Pharmacology, Merck & Co., Inc., Kenilworth, New Jersey, United States of America
| | - Kevin Knagge
- David H Murdock Research Institute, Kannapolis, North Carolina, United States of America
| | - Paul E. Carrington
- Cardio-Metabolic Diseases, Merck & Co., Inc., Kenilworth, New Jersey, United States of America
| | - William K. Hagmann
- Chemistry, Merck & Co., Inc., Kenilworth, New Jersey, United States of America
| | - Maria E. Trujillo
- In Vivo Pharmacology, Merck & Co., Inc., Kenilworth, New Jersey, United States of America
- * E-mail:
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23
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Albury-Warren TM, Pandey V, Spinel LP, Masternak MM, Altomare DA. Prediabetes linked to excess glucagon in transgenic mice with pancreatic active AKT1. J Endocrinol 2016; 228:49-59. [PMID: 26487674 PMCID: PMC4803065 DOI: 10.1530/joe-15-0288] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/20/2015] [Indexed: 12/31/2022]
Abstract
Protein kinase B/AKT has three isoforms (AKT1-3) and is renowned for its central role in the regulation of cell growth and proliferation, due to its constitutive activation in various cancers. AKT2, which is highly expressed in insulin-responsive tissues, has been identified as a primary regulator of glucose metabolism as Akt2 knockout mice (Akt2(-/-)) are glucose-intolerant and insulin-resistant. However, the role of AKT1 in glucose metabolism is not as clearly defined. We previously showed that mice with myristoylated Akt1 (AKT1(Myr)) expressed through a bicistronic Pdx1-TetA and TetO-MyrAkt1 system were susceptible to islet cell carcinomas, and in this study we characterized an early onset, prediabetic phenotype. Beginning at weaning (3 weeks of age), the glucose-intolerant AKT1(Myr) mice exhibited non-fasted hyperglycemia, which progressed to fasted hyperglycemia by 5 months of age. The glucose intolerance was attributed to a fasted hyperglucagonemia, and hepatic insulin resistance detectable by reduced phosphorylation of the insulin receptor following insulin injection into the inferior vena cava. In contrast, treatment with doxycycline diet to turn off the transgene caused attenuation of the non-fasted and fasted hyperglycemia, thus affirming AKT1 hyperactivation as the trigger. Collectively, this model highlights a novel glucagon-mediated mechanism by which AKT1 hyperactivation affects glucose homeostasis and provides an avenue to better delineate the molecular mechanisms responsible for diabetes mellitus and the potential association with pancreatic cancer.
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Affiliation(s)
- Toya M Albury-Warren
- Burnett School of Biomedical SciencesCollege of Medicine, University of Central Florida, 6900 Lake Nona Boulevard, Orlando, Florida 32827, USADepartment of Head and Neck SurgeryThe Greater Poland Cancer Centre, 61-866 Poznan, Poland
| | - Veethika Pandey
- Burnett School of Biomedical SciencesCollege of Medicine, University of Central Florida, 6900 Lake Nona Boulevard, Orlando, Florida 32827, USADepartment of Head and Neck SurgeryThe Greater Poland Cancer Centre, 61-866 Poznan, Poland
| | - Lina P Spinel
- Burnett School of Biomedical SciencesCollege of Medicine, University of Central Florida, 6900 Lake Nona Boulevard, Orlando, Florida 32827, USADepartment of Head and Neck SurgeryThe Greater Poland Cancer Centre, 61-866 Poznan, Poland
| | - Michal M Masternak
- Burnett School of Biomedical SciencesCollege of Medicine, University of Central Florida, 6900 Lake Nona Boulevard, Orlando, Florida 32827, USADepartment of Head and Neck SurgeryThe Greater Poland Cancer Centre, 61-866 Poznan, Poland Burnett School of Biomedical SciencesCollege of Medicine, University of Central Florida, 6900 Lake Nona Boulevard, Orlando, Florida 32827, USADepartment of Head and Neck SurgeryThe Greater Poland Cancer Centre, 61-866 Poznan, Poland
| | - Deborah A Altomare
- Burnett School of Biomedical SciencesCollege of Medicine, University of Central Florida, 6900 Lake Nona Boulevard, Orlando, Florida 32827, USADepartment of Head and Neck SurgeryThe Greater Poland Cancer Centre, 61-866 Poznan, Poland
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24
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Abstract
Sitting too much kills. Epidemiological, physiological and molecular data suggest that sedentary lifestyle can explain, in part, how modernity is associated with obesity, more than 30 chronic diseases and conditions and high healthcare costs. Excessive sitting--sitting disease--is not innate to the human condition. People were designed to be bipedal and, before the industrial revolution, people moved substantially more throughout the day than they do presently. It is encouraging that solutions exist to reverse sitting disease. Work environments, schools, communities and cities can be re-imagined and re-invented as walking spaces, and people thereby offered more active, happier, healthier and more productive lives.
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Affiliation(s)
- James A Levine
- Mayo Clinic, 13400 East Shea Blvd, Scottsdale, AZ, 85259, USA,
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25
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Detection of Abnormalities in Type II Diabetic Patients Using Particle Filters. J Med Biol Eng 2015. [DOI: 10.1007/s40846-015-0018-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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26
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Chung ST, Hsia DS, Chacko SK, Rodriguez LM, Haymond MW. Increased gluconeogenesis in youth with newly diagnosed type 2 diabetes. Diabetologia 2015; 58:596-603. [PMID: 25447079 PMCID: PMC4323952 DOI: 10.1007/s00125-014-3455-x] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Accepted: 11/03/2014] [Indexed: 12/21/2022]
Abstract
AIMS/HYPOTHESIS The role of increased gluconeogenesis as an important contributor to fasting hyperglycaemia at diabetes onset is not known. We evaluated the contribution of gluconeogenesis and glycogenolysis to fasting hyperglycaemia in newly diagnosed youths with type 2 diabetes following an overnight fast. METHODS Basal rates (μmol kg(FFM) (-1) min(-1)) of gluconeogenesis ((2)H2O), glycogenolysis and glycerol production ([(2)H5] glycerol) were measured in 18 adolescents (nine treatment naive diabetic and nine normal-glucose-tolerant obese adolescents). RESULTS Type 2 diabetes was associated with higher gluconeogenesis (9.2 ± 0.6 vs 7.0 ± 0.3 μmol kg(FFM) (-1) min(-1), p < 0.01), plasma fasting glucose (7.0 ± 0.6 vs 5.0 ± 0.2 mmol/l, p = 0.004) and insulin (300 ± 30 vs 126 ± 31 pmol/l, p = 0.001). Glucose production and glycogenolysis were similar between the groups (15.4 ± 0.3 vs 12.4 ± 1.4 μmol kg(FFM) (-1) min(-1), p = 0.06; and 6.2 ± 0.8 vs 5.3 ± 0.7 μmol kg(FFM) (-1) min(-1), p = 0.5, respectively). After controlling for differences in adiposity, gluconeogenesis, glycogenolysis and glucose production were higher in diabetic youth (p ≤ 0.02). Glycerol concentration (84 ± 6 vs 57 ± 6 μmol/l, p = 0.01) and glycerol production (5.0 ± 0.3 vs 3.6 ± 0.5 μmol kg(FFM) (-1) min(-1), p = 0.03) were 40% higher in youth with diabetes. The increased glycerol production could account for only ~1/3 of substrate needed for the increased gluconeogenesis in diabetic youth. CONCLUSION/INTERPRETATIONS Increased gluconeogenesis was a major contributor to fasting hyperglycaemia and hepatic insulin resistance in newly diagnosed untreated adolescents and was an early pathological feature of type 2 diabetes. Increased glycerol availability may represent a significant source of new carbon substrates for increased gluconeogenesis but would not account for all the carbons required to sustain the increased rates.
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Affiliation(s)
- Stephanie T Chung
- National Institute of Diabetes and Digestive and Kidney Diseases, NIH 10 Center Dr. Bld 10-CRC, RM 5-5740, MSC 1612, Bethesda, MD, 20892-1612, USA,
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27
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Kowalski GM, Bruce CR. The regulation of glucose metabolism: implications and considerations for the assessment of glucose homeostasis in rodents. Am J Physiol Endocrinol Metab 2014; 307:E859-71. [PMID: 25205823 DOI: 10.1152/ajpendo.00165.2014] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The incidence of insulin resistance and type 2 diabetes (T2D) is increasing at alarming rates. In the quest to understand the underlying causes of and to identify novel therapeutic targets to treat T2D, scientists have become increasingly reliant on the use of rodent models. Here, we provide a discussion on the regulation of rodent glucose metabolism, highlighting key differences and similarities that exist between rodents and humans. In addition, some of the issues and considerations associated with assessing glucose homeostasis and insulin action are outlined. We also discuss the role of the liver vs. skeletal muscle in regulating whole body glucose metabolism in rodents, emphasizing the importance of defective hepatic glucose metabolism in the development of impaired glucose tolerance, insulin resistance, and T2D.
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Affiliation(s)
- Greg M Kowalski
- Centre for Physical Activity and Nutrition Research, School of Exercise and Nutrition Sciences, Deakin University, Burwood, Victoria, Australia
| | - Clinton R Bruce
- Centre for Physical Activity and Nutrition Research, School of Exercise and Nutrition Sciences, Deakin University, Burwood, Victoria, Australia
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28
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Limberg JK, Taylor JL, Dube S, Basu R, Basu A, Joyner MJ, Wehrwein EA. Role of the carotid body chemoreceptors in baroreflex control of blood pressure during hypoglycaemia in humans. Exp Physiol 2014; 99:640-50. [PMID: 24414173 DOI: 10.1113/expphysiol.2013.076869] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Activation of the carotid body chemoreceptors with hypoxia alters baroreceptor-mediated responses. We aimed to examine whether this relationship can be translated to other chemoreceptor stimuli (i.e. hypoglycaemia) by testing the following hypotheses: (i) activation of the carotid body chemoreceptors with hypoglycaemia would reduce spontaneous cardiac baroreflex sensitivity (sCBRS) in healthy humans; and (ii) desensitization of the carotid chemoreceptors with hyperoxia would restore sCBRS to baseline levels during hypoglycaemia. Ten young healthy adults completed two 180 min hyperinsulinaemic [2 mU (kg fat-free mass)(-1) min(-1)], hypoglycaemic (∼ 3.2 μmol ml(-1)) clamps, separated by at least 1 week and randomized to normoxia (arterial partial pressure of O2, 122 ± 10 mmHg) or hyperoxia (arterial partial pressure of O2, 424 ± 123 mmHg; to blunt activation of the carotid body glomus cells). Changes in heart rate, blood pressure, plasma catecholamines, heart rate variability (HRV) and sCBRS were assessed. During hypoglycaemia, HRV and sCBRS were reduced (P < 0.05) and the baroreflex working range was shifted to higher heart rates. When hyperoxia was superimposed on hypoglycaemia, there was a greater reduction in blood pressure and a blunted rise in heart rate when compared with normoxic conditions (P < 0.05); however, there was no detectable effect of hyperoxia on sCBRS or HRV during hypoglycaemia (P > 0.05). In summary, hypoglycaemia-mediated changes in HRV and sCBRS cannot be attributed exclusively to the carotid chemoreceptors; however, the chemoreceptors appear to play a role in resetting the baroreflex working range during hypoglycaemia.
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Affiliation(s)
- Jacqueline K Limberg
- * Department of Anesthesiology, Mayo Clinic, 200 1st Street SW, SMH Joseph 4-184, Rochester, MN 55905, USA.
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29
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Insulin sensitivity assessed by stable isotopes with oral glucose administration: validation with euglycaemic clamp. ISRN ENDOCRINOLOGY 2013; 2013:189412. [PMID: 24363940 PMCID: PMC3864082 DOI: 10.1155/2013/189412] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Accepted: 09/11/2013] [Indexed: 11/17/2022]
Abstract
Methods of determining insulin sensitivity that use an oral challenge of glucose are preferred to those using intravenous administration since the measurement is made in conditions more akin to normal physiology. One previously reported protocol (ODILE) studies glucose uptake in isolation from absorption and endogenous production by the intravenous administration of tracer approximately forty-five minutes after the oral dose is given. However, this methodology has not been validated against other accredited procedures. This study utilizes the euglycemic hyperinsulinemic clamp in order to validate the ODILE method.
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30
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Rajpal A, Dube S, Carvalho F, Simoes AR, Figueiredo A, Basu A, Jones J, Basu R. Effects of transaldolase exchange on estimates of gluconeogenesis in type 2 diabetes. Am J Physiol Endocrinol Metab 2013; 305:E465-74. [PMID: 23736541 PMCID: PMC3891223 DOI: 10.1152/ajpendo.00245.2013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Transaldolase (TA) exchange overestimates gluconeogenesis measured with deuterated water (²H₂O). However, it is unknown whether TA differs in people with type 2 diabetes (T2DM). ²H₂O was ingested, and [1-¹³C]acetate and [3-³H]glucose were infused in T2DM (n = 10) and healthy nondiabetic (ND; n = 8) subjects. TA was assessed from the ratio of ¹³C3 to ¹³C4 glucose enrichment (¹³C3/¹³C4) measured by ¹³C NMR. Glucose turnover was measured before (~16-h fast) and during hyperglycemic (~10 mM) moderate-dose insulin (~0.35 mU·kg⁻¹·min⁻¹) clamp. ¹³C3/¹³C4 in T2DM vs. ND was <1.0 and not different at baseline and clamp, indicating equivalent TA. To determine whether incomplete triose phosphate isomerase (TPI) exchange contributed to asymmetric ¹³C3/¹³C4, [U-¹³C]glycerol was infused in lieu of [1-¹³C]acetate during a separate visit in a subset of ND (n = 7) subjects. Ratio of ¹³C3/¹³C4 obtained following either tracer was <1.0 at baseline and during clamp, indicating that TPI exchange was essentially complete and did not contribute to asymmetric glucose enrichment. Uncorrected and corrected rates of gluconeogenesis were no different (P = not significant) in T2DM vs. ND both at baseline and during clamp. TA correction resulted in equivalent estimates of corrected gluconeogenesis in T2DM and ND that were ~25-35% lower than uncorrected gluconeogenesis both at baseline and during the clamp. The asymmetric enrichment of glucose from ¹³C-gluconeogenic tracers is attributable to TA exchange and can be utilized to correct for TA exchange. In conclusion, TA exchange does not differ between T2DM and ND under fasting or hyperglycemic clamp conditions, and the ²H₂O method continues to provide an accurate estimation of gluconeogenesis.
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Affiliation(s)
- Aman Rajpal
- Division of Endocrinology, Diabetes, Metabolism, and Nutrition, Mayo Clinic College of Medicine, Rochester, Minnesota
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31
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Coate KC, Kraft G, Irimia JM, Smith MS, Farmer B, Neal DW, Roach PJ, Shiota M, Cherrington AD. Portal vein glucose entry triggers a coordinated cellular response that potentiates hepatic glucose uptake and storage in normal but not high-fat/high-fructose-fed dogs. Diabetes 2013; 62:392-400. [PMID: 23028137 PMCID: PMC3554368 DOI: 10.2337/db12-0417] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The cellular events mediating the pleiotropic actions of portal vein glucose (PoG) delivery on hepatic glucose disposition have not been clearly defined. Likewise, the molecular defects associated with postprandial hyperglycemia and impaired hepatic glucose uptake (HGU) following consumption of a high-fat, high-fructose diet (HFFD) are unknown. Our goal was to identify hepatocellular changes elicited by hyperinsulinemia, hyperglycemia, and PoG signaling in normal chow-fed (CTR) and HFFD-fed dogs. In CTR dogs, we demonstrated that PoG infusion in the presence of hyperinsulinemia and hyperglycemia triggered an increase in the activity of hepatic glucokinase (GK) and glycogen synthase (GS), which occurred in association with further augmentation in HGU and glycogen synthesis (GSYN) in vivo. In contrast, 4 weeks of HFFD feeding markedly reduced GK protein content and impaired the activation of GS in association with diminished HGU and GSYN in vivo. Furthermore, the enzymatic changes associated with PoG sensing in chow-fed animals were abolished in HFFD-fed animals, consistent with loss of the stimulatory effects of PoG delivery. These data reveal new insight into the molecular physiology of the portal glucose signaling mechanism under normal conditions and to the pathophysiology of aberrant postprandial hepatic glucose disposition evident under a diet-induced glucose-intolerant condition.
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Affiliation(s)
- Katie C. Coate
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Guillaume Kraft
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Jose M. Irimia
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Marta S. Smith
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Ben Farmer
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Doss W. Neal
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Peter J. Roach
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Masakazu Shiota
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Alan D. Cherrington
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
- Corresponding author: Alan D. Cherrington,
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32
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Short KR, Irving BA, Basu A, Johnson CM, Nair KS, Basu R. Effects of type 2 diabetes and insulin on whole-body, splanchnic, and leg protein metabolism. J Clin Endocrinol Metab 2012; 97:4733-41. [PMID: 23032060 PMCID: PMC3591680 DOI: 10.1210/jc.2012-2533] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
CONTEXT Type 2 diabetes (T2D) is characterized by insulin resistance to glucose metabolism. Most studies suggest that protein metabolism is unaffected by T2D, but regional protein metabolism and response to multiple doses of insulin have not been examined. OBJECTIVE Our objective was to determine whether insulin regulation of splanchnic and leg protein metabolism are affected by T2D during hyperglycemia and graded insulin levels. DESIGN AND SETTING We conducted a cross-sectional study at an academic medical center. PARTICIPANTS T2D and non-T2D adults were matched for age (62 yr) and body mass index (30 kg/m(2)). INTERVENTIONS Glucose was maintained at approximately 9 mmol/liter while insulin was infused at three progressively higher rates, achieving circulating concentrations of approximately 150, 350, and 700 pmol/liter, respectively. MAIN OUTCOME MEASURES Protein kinetics were measured using labeled phenylalanine (Phe) and tyrosine (Tyr). RESULTS Whole-body protein breakdown and synthesis rates were higher in T2D but declined with increasing insulin in both groups. Leg Phe and Tyr appearance and disappearance and estimates of protein breakdown and synthesis, respectively, were higher in T2D but did not decline significantly with insulin, resulting in similar net balance between groups. Splanchnic response to insulin was blunted in T2D, shown by a smaller reduction in rates of disappearance and net balance of Phe and Tyr as insulin increased. Splanchnic conversion of Phe to Tyr was lower in T2D and less sensitive to insulin, whereas nonsplanchnic Phe to Tyr tended to be higher in T2D. CONCLUSIONS T2D results in higher whole-body, splanchnic, and leg protein turnover and blunts the insulin-mediated suppression of splanchnic protein anabolism under hyperglycemic, hyperinsulinemic conditions.
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König M, Holzhütter HG. Kinetic modeling of human hepatic glucose metabolism in type 2 diabetes mellitus predicts higher risk of hypoglycemic events in rigorous insulin therapy. J Biol Chem 2012; 287:36978-89. [PMID: 22977253 DOI: 10.1074/jbc.m112.382069] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
A major problem in the insulin therapy of patients with diabetes type 2 (T2DM) is the increased occurrence of hypoglycemic events which, if left untreated, may cause confusion or fainting and in severe cases seizures, coma, and even death. To elucidate the potential contribution of the liver to hypoglycemia in T2DM we applied a detailed kinetic model of human hepatic glucose metabolism to simulate changes in glycolysis, gluconeogenesis, and glycogen metabolism induced by deviations of the hormones insulin, glucagon, and epinephrine from their normal plasma profiles. Our simulations reveal in line with experimental and clinical data from a multitude of studies in T2DM, (i) significant changes in the relative contribution of glycolysis, gluconeogenesis, and glycogen metabolism to hepatic glucose production and hepatic glucose utilization; (ii) decreased postprandial glycogen storage as well as increased glycogen depletion in overnight fasting and short term fasting; and (iii) a shift of the set point defining the switch between hepatic glucose production and hepatic glucose utilization to elevated plasma glucose levels, respectively, in T2DM relative to normal, healthy subjects. Intriguingly, our model simulations predict a restricted gluconeogenic response of the liver under impaired hormonal signals observed in T2DM, resulting in an increased risk of hypoglycemia. The inability of hepatic glucose metabolism to effectively counterbalance a decline of the blood glucose level becomes even more pronounced in case of tightly controlled insulin treatment. Given this Janus face mode of action of insulin, our model simulations underline the great potential that normalization of the plasma glucagon profile may have for the treatment of T2DM.
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Affiliation(s)
- Matthias König
- Institute of Biochemistry, University Medicine Charité Berlin, 10117 Berlin, Germany.
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34
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Girgis CM, Cheng K, Scott CH, Gunton JE. Novel links between HIFs, type 2 diabetes, and metabolic syndrome. Trends Endocrinol Metab 2012; 23:372-80. [PMID: 22766319 DOI: 10.1016/j.tem.2012.05.003] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/29/2012] [Revised: 05/03/2012] [Accepted: 05/05/2012] [Indexed: 12/25/2022]
Abstract
Hypoxia inducible factors (HIFs) are master-regulators of cellular responses to hypoxia, and thus are crucial for survival. HIFs also play a role in regulating cellular processes in β-cells, liver, muscle, and adipose tissue, have effects on the regulation of weight, and play a role in type 2 diabetes (T2D). Indeed, in people with T2D the HIF pathway is dyregulated in major metabolic tissues involved in the pathogenesis of diabetes. This review covers the contrasting, complementary and conflicting effects of decreasing and increasing HIFs in various tissues, and shows that a delicate balance exists between HIF levels and optimal metabolic function. We propose that increasing the activity of HIFs might be a potential therapeutic strategy for treating T2D.
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Affiliation(s)
- Christian M Girgis
- Garvan Institute of Medical Research, 384 Victoria Street, Darlinghurst, NSW 2010, Australia
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Saderi N, Salgado-Delgado R, Avendaño-Pradel R, Basualdo MDC, Ferri GL, Chávez-Macías L, Roblera JEO, Escobar C, Buijs RM. NPY and VGF immunoreactivity increased in the arcuate nucleus, but decreased in the nucleus of the Tractus Solitarius, of type-II diabetic patients. PLoS One 2012; 7:e40070. [PMID: 22808091 PMCID: PMC3394787 DOI: 10.1371/journal.pone.0040070] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2012] [Accepted: 05/31/2012] [Indexed: 11/23/2022] Open
Abstract
Ample animal studies demonstrate that neuropeptides NPY and α-MSH expressed in Arcuate Nucleus and Nucleus of the Tractus Solitarius, modulate glucose homeostasis and food intake. In contrast is the absence of data validating these observations for human disease. Here we compare the post mortem immunoreactivity of the metabolic neuropeptides NPY, αMSH and VGF in the infundibular nucleus, and brainstem of 11 type-2 diabetic and 11 non-diabetic individuals. α-MSH, NPY and tyrosine hydroxylase in human brain are localized in the same areas as in rodent brain. The similar distribution of NPY, α-MSH and VGF indicated that these neurons in the human brain may share similar functionality as in the rodent brain. The number of NPY and VGF immuno positive cells was increased in the infundibular nucleus of diabetic subjects in comparison to non-diabetic controls. In contrast, NPY and VGF were down regulated in the Nucleus of the Tractus Solitarius of diabetic patients. These results suggest an activation of NPY producing neurons in the arcuate nucleus, which, according to animal experimental studies, is related to a catabolic state and might be the basis for increased hepatic glucose production in type-2 diabetes.
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Affiliation(s)
- Nadia Saderi
- Dept. de Biologia Celular y Fisiologia, Instituto de Investigaciones Biomedicas, UNAM, Mexico City, Mexico
- NEF-Lab, Dept. Cytomorphology, University of Cagliari, Monserrato (CA), Italy
| | - Roberto Salgado-Delgado
- Dept. de Biologia Celular y Fisiologia, Instituto de Investigaciones Biomedicas, UNAM, Mexico City, Mexico
- Facultad de Ciencias, UASLP, San Luis Potosì, Mexico
| | | | - Maria del Carmen Basualdo
- Dept. de Biologia Celular y Fisiologia, Instituto de Investigaciones Biomedicas, UNAM, Mexico City, Mexico
| | - Gian-Luca Ferri
- NEF-Lab, Dept. Cytomorphology, University of Cagliari, Monserrato (CA), Italy
| | | | | | - Carolina Escobar
- Dept. de Anatomia, Facultad de Medicina, UNAM, Mexico City, Mexico
| | - Ruud M. Buijs
- Dept. de Biologia Celular y Fisiologia, Instituto de Investigaciones Biomedicas, UNAM, Mexico City, Mexico
- * E-mail:
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Quantifying the contribution of the liver to glucose homeostasis: a detailed kinetic model of human hepatic glucose metabolism. PLoS Comput Biol 2012; 8:e1002577. [PMID: 22761565 PMCID: PMC3383054 DOI: 10.1371/journal.pcbi.1002577] [Citation(s) in RCA: 130] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2011] [Accepted: 05/08/2012] [Indexed: 02/02/2023] Open
Abstract
Despite the crucial role of the liver in glucose homeostasis, a detailed mathematical model of human hepatic glucose metabolism is lacking so far. Here we present a detailed kinetic model of glycolysis, gluconeogenesis and glycogen metabolism in human hepatocytes integrated with the hormonal control of these pathways by insulin, glucagon and epinephrine. Model simulations are in good agreement with experimental data on (i) the quantitative contributions of glycolysis, gluconeogenesis, and glycogen metabolism to hepatic glucose production and hepatic glucose utilization under varying physiological states. (ii) the time courses of postprandial glycogen storage as well as glycogen depletion in overnight fasting and short term fasting (iii) the switch from net hepatic glucose production under hypoglycemia to net hepatic glucose utilization under hyperglycemia essential for glucose homeostasis (iv) hormone perturbations of hepatic glucose metabolism. Response analysis reveals an extra high capacity of the liver to counteract changes of plasma glucose level below 5 mM (hypoglycemia) and above 7.5 mM (hyperglycemia). Our model may serve as an important module of a whole-body model of human glucose metabolism and as a valuable tool for understanding the role of the liver in glucose homeostasis under normal conditions and in diseases like diabetes or glycogen storage diseases.
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Jensen MD, Nielsen S, Gupta N, Basu R, Rizza RA. Insulin clearance is different in men and women. Metabolism 2012; 61:525-30. [PMID: 22000585 PMCID: PMC3274596 DOI: 10.1016/j.metabol.2011.08.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2011] [Revised: 08/22/2011] [Accepted: 08/23/2011] [Indexed: 11/29/2022]
Abstract
Insulin is often infused based upon total body weight (TBW) or fat-free mass (FFM) for glucose clamp protocols. We observed greater insulin concentrations in men than women using this approach and examined whether splanchnic insulin extraction accounts for the differences. Whole-body insulin clearance was measured during a pancreatic clamp study (somatostatin to inhibit islet hormone secretion) including 13 adults (6 men); and whole-body insulin clearance was measured during a euglycemic, hyperinsulinemic clamp study including 27 adults (13 men). Femoral artery and hepatic vein blood samples were collected to measure splanchnic insulin balance. For the pancreatic clamp study, insulin was infused at rates of 0.5, 1.0, and 2.0 mU/kg of TBW per minute; and for the euglycemic, hyperinsulinemic clamp study, insulin was infused at 2.5 mU/kg of FFM per minute. Significantly greater arterial insulin concentrations were found in men than women. Splanchnic plasma flow was similar in men and women in both protocols. Splanchnic insulin extraction and the fraction of infused insulin removed by splanchnic bed were significantly greater in men than in women. However, whole-body insulin clearance was greater in women than men. Infusing insulin per body weight or FFM results in higher plasma insulin concentrations in men than women. Splanchnic insulin extraction is greater in men, indicating that greater peripheral insulin clearance in women accounts for the sex differences we observed. This finding has implications for insulin clamp study design and raises the question of which tissues take up more insulin in women.
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Vahidi O, Kwok K, Gopaluni R, Sun L. Developing a physiological model for type II diabetes mellitus. Biochem Eng J 2011. [DOI: 10.1016/j.bej.2011.02.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Johnson PM, Chen SS, Santomango TS, Williams PE, Lacy DB, McGuinness OP. Continuous low-dose fructose infusion does not reverse glucagon-mediated decrease in hepatic glucose utilization. Metabolism 2011; 60:867-73. [PMID: 20940071 PMCID: PMC3736817 DOI: 10.1016/j.metabol.2010.08.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2009] [Revised: 08/18/2010] [Accepted: 08/18/2010] [Indexed: 01/04/2023]
Abstract
An adaptation to continuous total parenteral nutrition (TPN; 75% of nonprotein calories as glucose) is the liver becomes a major consumer of glucose with lactate release as a by-product. The liver is able to further increase liver glucose uptake when a small dose of fructose is acutely infused via the portal system. Glucagon, commonly elevated during inflammatory stress, is a potent inhibitor of glucose uptake by the liver during TPN. The aim was to determine if continuous fructose infusion could overcome the glucagon-mediated decrease in hepatic glucose uptake. Studies were performed in conscious, insulin-treated, chronically catheterized, pancreatectomized dogs that adapted to TPN for 33 hours. They were then assigned to 1 of 4 groups: TPN (C), TPN + fructose (4.4 μmol kg(-1) min(-1); F), TPN + glucagon (0.2 pmol kg(-1) min(-1); GGN), or TPN + fructose and glucagon (F + GGN) for an additional 63 hours (33-96 hours). Insulin, fructose, and glucagon were infused into the portal vein. During that period, all animals received a fixed insulin infusion of 0.4 mU·kg(-1)·min(-1) (33-96 hours); and the glucose infusion rates were adjusted to maintain euglycemia (6.6 mmol/L). Continuous fructose infusion was unable to further enhance net hepatic glucose uptake (in micromoles per kilogram per minute) (31.1 ± 2.8 vs 36.1 ± 5.0; C vs F), nor was it able to overcome glucagon-mediated decrease in net hepatic glucose uptake (10.0 ± 4.4 vs 12.2 ± 3.9; GGN vs F + GGN). In summary, continuous fructose infusion cannot augment liver glucose uptake during TPN; nor can it overcome the inhibitory effects of glucagon.
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Affiliation(s)
- Paulette M Johnson
- Division of Pediatric Critical Care Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232-0615, USA
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Basu R, Peterson J, Rizza R, Khosla S. Effects of physiological variations in circulating insulin levels on bone turnover in humans. J Clin Endocrinol Metab 2011; 96:1450-5. [PMID: 21325461 PMCID: PMC3085206 DOI: 10.1210/jc.2010-2877] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
CONTEXT Recent studies in mice have demonstrated that insulin signaling in osteoblasts stimulates bone formation and reduces osteoprotegerin production; the latter results in an increase in bone resorption, which then leads to the release of undercarboxylated osteocalcin from bone. Undercarboxylated osteocalcin, in turn, enhances insulin sensitivity. OBJECTIVE The objective of the study was to test whether physiological changes in insulin levels regulate bone metabolism in humans. DESIGN This investigation was an analysis of samples from a prospective study. SETTING The study was conducted at a clinical research unit. PARTICIPANTS AND INTERVENTIONS Fourteen subjects underwent a 7-h stepped insulin infusion accompanied by a glucose clamp and somatostatin infusion along with replacement infusions of GH and glucagon, thus isolating possible effects of insulin on bone. Insulin was infused at rates achieving low (∼150 pmol/liter), intermediate (∼350 pmol/liter), or high (∼700 pmol/liter) plasma insulin levels. MAIN OUTCOME MEASURES Bone turnover markers, undercarboxylated osteocalcin, and osteoprotegerin levels at the end of the low, intermediate, and high dose insulin infusions were measured. RESULTS Values for the outcome measures at the end of the intermediate- and high-dose insulin infusions were no different from values at the end of the low-dose insulin infusion. However, measures of insulin sensitivity (glucose infusion and disappearance rates) correlated positively with C-terminal telopeptide of type I collagen levels. CONCLUSIONS Acute changes in insulin levels, as occur during meals, do not regulate bone turnover, undercarboxylated osteocalcin, or osteoprotegerin levels. However, the correlation of measures of insulin sensitivity with bone resorption suggests the need for further studies in humans on the possible regulation of bone metabolism by insulin.
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Affiliation(s)
- Rita Basu
- Endocrine Research Unit, College of Medicine, Mayo Clinic, 200 First Street SW, Rochester, Minnesota 55905, USA
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Winnick JJ, An Z, Ramnanan CJ, Smith M, Irimia JM, Neal DW, Moore MC, Roach PJ, Cherrington AD. Hepatic glycogen supercompensation activates AMP-activated protein kinase, impairs insulin signaling, and reduces glycogen deposition in the liver. Diabetes 2011; 60:398-407. [PMID: 21270252 PMCID: PMC3028338 DOI: 10.2337/db10-0592] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE The objective of this study was to determine how increasing the hepatic glycogen content would affect the liver's ability to take up and metabolize glucose. RESEARCH DESIGN AND METHODS During the first 4 h of the study, liver glycogen deposition was stimulated by intraportal fructose infusion in the presence of hyperglycemic-normoinsulinemia. This was followed by a 2-h hyperglycemic-normoinsulinemic control period, during which the fructose infusion was stopped, and a 2-h experimental period in which net hepatic glucose uptake (NHGU) and disposition (glycogen, lactate, and CO(2)) were measured in the absence of fructose but in the presence of a hyperglycemic-hyperinsulinemic challenge including portal vein glucose infusion. RESULTS Fructose infusion increased net hepatic glycogen synthesis (0.7 ± 0.5 vs. 6.4 ± 0.4 mg/kg/min; P < 0.001), causing a large difference in hepatic glycogen content (62 ± 9 vs. 100 ± 3 mg/g; P < 0.001). Hepatic glycogen supercompensation (fructose infusion group) did not alter NHGU, but it reduced the percent of NHGU directed to glycogen (79 ± 4 vs. 55 ± 6; P < 0.01) and increased the percent directed to lactate (12 ± 3 vs. 29 ± 5; P = 0.01) and oxidation (9 ± 3 vs. 16 ± 3; P = NS). This change was associated with increased AMP-activated protein kinase phosphorylation, diminished insulin signaling, and a shift in glycogenic enzyme activity toward a state discouraging glycogen accumulation. CONCLUSIONS These data indicate that increases in hepatic glycogen can generate a state of hepatic insulin resistance, which is characterized by impaired glycogen synthesis despite preserved NHGU.
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Affiliation(s)
- Jason J Winnick
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, Tennessee, USA.
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Abstract
The objective of this research is to gain a greater understanding of the cause of fasting and postprandial hyperglycemia in people with type 2 diabetes. Endogenous glucose production is excessive before eating and fails to appropriately suppress after eating in people with type 2 diabetes. This is due in part to impaired insulin-induced suppression of endogenous glucose production, which is observed early in the evolution of type 2 diabetes. Increased rates of gluconeogenesis and perhaps glycogenolysis contribute to hepatic insulin resistance. Insulin-induced stimulation of hepatic glucose uptake and hepatic glycogen synthesis are reduced in people with type 2 diabetes primarily due to decreased uptake of extracellular glucose presumably because of inadequate activation of hepatic glucokinase. Delayed insulin secretion results in higher peak glucose concentrations particularly when suppression of glucagon is impaired, whereas insulin resistance prolongs the duration of hyperglycemia, which can be marked when both hepatic and extra-hepatic insulin resistance are present. The premise of these studies, as well as those performed by many other investigators, is that an understanding of the pathogenesis of type 2 diabetes will enable the development of targeted therapies that are directed toward correcting specific metabolic defects in a given individual. I, as well as many other investigators, believe that such therapies are likely to be more effective and to have a lower risk than would occur if everyone were treated the same regardless of the underlying cause of their hyperglycemia. While we do not yet have sufficient knowledge to truly individualize therapy, in my opinion this approach will be the norm in the not too distant future.
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Affiliation(s)
- Robert A Rizza
- Division of Endocrinology, Diabetes, Metabolism and Nutrition, Mayo Clinic College of Medicine, Rochester, Minnesota, USA.
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Magkos F, Wang X, Mittendorfer B. Metabolic actions of insulin in men and women. Nutrition 2010; 26:686-93. [PMID: 20392600 DOI: 10.1016/j.nut.2009.10.013] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2009] [Accepted: 10/24/2009] [Indexed: 12/31/2022]
Abstract
Insulin is an important regulator of glucose, lipid, and protein metabolism. It suppresses hepatic glucose and triglyceride production, inhibits adipose tissue lipolysis and whole-body and muscle proteolysis, and stimulates glucose uptake in muscle. In this review we discuss what is currently known about the control of substrate metabolism by insulin in men and women. The data available so far indicate that women are more sensitive to insulin with regards to glucose metabolism (both in the liver and in muscle), whereas there are no differences between men and women in insulin action on lipolysis. Potential differences exist in the regulation of plasma triglyceride concentration and protein metabolism by insulin and in changes in insulin action in response to stimuli (e.g., weight loss and exercise) that are known to alter insulin sensitivity. However, these areas have not been studied comprehensively enough to draw firm conclusions.
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Affiliation(s)
- Faidon Magkos
- Center for Human Nutrition, Washington University School of Medicine, St. Louis, MO, USA
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Monte SV, Schentag JJ, Adelman MH, Paladino JA. Glucose supply and insulin demand dynamics of antidiabetic agents. J Diabetes Sci Technol 2010; 4:365-81. [PMID: 20307399 PMCID: PMC2864174 DOI: 10.1177/193229681000400219] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
BACKGROUND For microvascular outcomes, there is compelling historical and contemporary evidence for intensive blood glucose reduction in patients with either type 1 diabetes mellitus (T1DM) or type 2 diabetes mellitus (T2DM). There is also strong evidence to support macrovascular benefit with intensive blood glucose reduction in T1DM. Similar evidence remains elusive for T2DM. Because cardiovascular outcome trials utilizing conventional algorithms to attain intensive blood glucose reduction have not demonstrated superiority to less aggressive blood glucose reduction (Action to Control Cardiovascular Risk in Diabetes; Action in Diabetes and Vascular Disease: Preterax and Diamicron Modified Release Controlled Evaluation; and Veterans Affairs Diabetes Trial), it should be considered that the means by which the blood glucose is reduced may be as important as the actual blood glucose. METHODS By identifying quantitative differences between antidiabetic agents on carbohydrate exposure (CE), hepatic glucose uptake (HGU), hepatic gluconeogenesis (GNG), insulin resistance (IR), peripheral glucose uptake (PGU), and peripheral insulin exposure (PIE), we created a pharmacokinetic/pharmacodynamic model to characterize the effect of the agents on the glucose supply and insulin demand dynamic. Glucose supply was defined as the cumulative percentage decrease in CE, increase in HGU, decrease in GNG, and decrease in IR, while insulin demand was defined as the cumulative percentage increase in PIE and PGU. With the glucose supply and insulin demand effects of each antidiabetic agent summated, the glucose supply (numerator) was divided by the insulin demand (denominator) to create a value representative of the glucose supply and insulin demand dynamic (SD ratio). RESULTS Alpha-glucosidase inhibitors (1.25), metformin (2.20), and thiazolidinediones (TZDs; 1.25-1.32) demonstrate a greater effect on glucose supply (SD ratio >1), while secretagogues (0.69-0.81), basal insulins (0.77-0.79), and bolus insulins (0.62-0.67) demonstrate a greater effect on insulin demand (SD ratio <1). CONCLUSION Alpha-glucosidase inhibitors, metformin, and TZDs demonstrate a greater effect on glucose supply, while secretagogues, basal insulin, and bolus insulin demonstrate a greater effect on insulin demand. Because T2DM cardiovascular outcome trials have not demonstrated macrovascular benefit with more aggressive blood glucose reduction when using conventional algorithms that predominantly focus on insulin demand, it would appear logical to consider a model that incorporates both the extent of blood glucose lowering (hemoglobin A1c) and the means by which the blood glucose was reduced (SD ratio) when considering macrovascular outcomes.
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Abstract
Type 2 diabetes mellitus (T2DM) is a chronic, progressive disorder that affects more than 230 million people worldwide and is expected to affect 366 million by 2030. Both the prevalence of T2DM and the cost of its long term complications has driven the focus and emphasis on treatments aimed at reducing hyperglycemia and controlling hypertension and dyslipidemia. In the last 5 years new glucose lowering drugs acting on novel pathways have been developed, licensed and launched. These drugs include the glucagon-like peptide (GLP-1) agonists, exenatide, and dipeptidyl peptidase (DPP-IV) inhibitors such as sitagliptin and saxagliptin. This review describes current approaches to T2DM treatment, focusing on newer agents which tend to be associated with less hypoglycemia and possible weight loss, and addresses the potential roles of novel oral pharmacologic agents in the late-stages of development that might provide new options for the management of this disease.
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Affiliation(s)
- Kristen M Kulasa
- Department of Medicine, University of California, Veterans Affairs San Diego Healthcare System, San Diego, CA 92161, USA.
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Winnick JJ, An Z, Moore MC, Ramnanan CJ, Farmer B, Shiota M, Cherrington AD. A physiological increase in the hepatic glycogen level does not affect the response of net hepatic glucose uptake to insulin. Am J Physiol Endocrinol Metab 2009; 297:E358-66. [PMID: 19470836 PMCID: PMC2724107 DOI: 10.1152/ajpendo.00043.2009] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To determine the effect of an acute increase in hepatic glycogen on net hepatic glucose uptake (NHGU) and disposition in response to insulin in vivo, studies were performed on two groups of dogs fasted 18 h. During the first 4 h of the study, somatostatin was infused peripherally, while insulin and glucagon were replaced intraportally in basal amounts. Hyperglycemia was brought about by glucose infusion, and either saline (n = 7) or fructose (n = 7; to stimulate NHGU and glycogen deposition) was infused intraportally. A 2-h control period then followed, during which the portal fructose and saline infusions were stopped, allowing NHGU and glycogen deposition in the fructose-infused animals to return to rates similar to those of the animals that received the saline infusion. This was followed by a 2-h experimental period, during which hyperglycemia was continued but insulin infusion was increased fourfold in both groups. During the initial 4-h glycogen loading period, NHGU averaged 1.18 +/- 0.27 and 5.55 +/- 0.53 mg x kg(-1) x min(-1) and glycogen synthesis averaged 0.72 +/- 0.24 and 3.98 +/- 0.57 mg x kg(-1) x min(-1) in the saline and fructose groups, respectively (P < 0.05). During the 2-h hyperinsulinemic period, NHGU rose from 1.5 +/- 0.4 and 0.9 +/- 0.2 to 3.1 +/- 0.6 and 2.5 +/- 0.5 mg x kg(-1) x min(-1) in the saline and fructose groups, respectively, a change of 1.6 mg x kg(-1) x min(-1) in both groups despite a significantly greater liver glycogen level in the fructose-infused group. Likewise, the metabolic fate of the extracted glucose (glycogen, lactate, or carbon dioxide) was not different between groups. These data indicate that an acute physiological increase in the hepatic glycogen content does not alter liver glucose uptake and storage under hyperglycemic/hyperinsulinemic conditions in the dog.
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Affiliation(s)
- Jason J Winnick
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, Tennessee 37232-6015, USA.
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Tokuyama K, Nagasaka S, Mori S, Takahashi N, Kusaka I, Kiyonaga A, Tanaka H, Shindo M, Ishibashi S. Hepatic insulin sensitivity assessed by integrated model of hepatic and peripheral glucose regulation. Diabetes Technol Ther 2009; 11:487-92. [PMID: 19698061 DOI: 10.1089/dia.2009.0011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
BACKGROUND The integrated model of hepatic and peripheral glucose metabolism incorporates a model for liver glucose metabolism into the two-compartment minimal model framework to describe endogenous glucose kinetics during a labeled intravenous glucose tolerance test (IVGTT). This model also provides a parametric description of endogenous glucose production (EGP). The present study extended the theoretical potential of the model by defining hepatic glucose effectiveness (hS(G)(2)) as the ability of glucose per se to inhibit EGP and hepatic insulin sensitivity (hS(1)(2)) as the ability of insulin to enhance glucose suppression of EGP. METHODS As a retrospective data base review of our previous study, we re-analyzed time courses of exogenous and endogenous glucose concentration during [6,6-(2)H(2)]glucose-labeled IVGTT (0.3 g/kg glucose), performed in 11 exercise-trained and 12 age-matched sedentary subjects. Model parameters of the two-compartment minimal model and of liver glucose metabolism were simultaneously identified to assess insulin sensitivity specific to stimulate glucose uptake (S(1)(2*)) and that specific to inhibit EGP (hS(1)(2)). The abilities of glucose per se to stimulate its own uptake (S(G)(2*)) and to inhibit EGP (hS(G)(2)) were also estimated. RESULTS Parameters of the integrated model were identified in all the subjects. Hepatic insulin sensitivity consisted of about one-third of total insulin sensitivity (S(1)(2*) + hS(1)(2)). Compared with the sedentary subjects, S(1)(2*), hS(1)(2), hS(G)(2) of the trained subjects were greater. CONCLUSIONS Because insulin resistance in liver and peripheral tissue may play a differential role in the pathogenesis of diabetes, this analysis can serve as a simple one-step approach to obtain metabolic indexes specific to EGP suppression and stimulating glucose uptake.
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Affiliation(s)
- Kumpei Tokuyama
- Institute of Health and Sport Sciences, University of Tsukuba, Tsukuba, Ibaraki, 305-8574 Japan.
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Abstract
Insulin remains the most effective and durable hypoglycemic agent for the treatment of diabetes. The addition of an effective oral insulin dosage form to the antidiabetes armamentarium may have significant benefits in terms of fostering compliance and adherence among patients, as well as physiologic advantages due to the fact that such a dosage form replicates the natural route of insulin secretion and absorption through the portal vein and targets the liver directly. Several companies have developed technological platforms that protect polypeptides and proteins from enzymatic hydrolysis, enable their transport across the epithelial lining, and promote their absorption from the gastrointestinal tract. A review of the potential physiological rationale and advantages, as well as of current pertinent technologies used specifically with insulin, is herewith provided.
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Affiliation(s)
- Ehud Arbit
- Oramed Pharmaceuticals, Jerusalem, Israel.
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Basu A, Dalla Man C, Basu R, Toffolo G, Cobelli C, Rizza RA. Effects of type 2 diabetes on insulin secretion, insulin action, glucose effectiveness, and postprandial glucose metabolism. Diabetes Care 2009; 32:866-72. [PMID: 19196896 PMCID: PMC2671126 DOI: 10.2337/dc08-1826] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE In this study, we sought to determine whether postprandial insulin secretion, insulin action, glucose effectiveness, and glucose turnover were abnormal in type 2 diabetes. RESEARCH DESIGN AND METHODS Fourteen subjects with type 2 diabetes and 11 nondiabetic subjects matched for age, weight, and BMI underwent a mixed-meal test using the triple-tracer technique. Indexes of insulin secretion, insulin action, and glucose effectiveness were assessed using the oral "minimal" and C-peptide models. RESULTS Fasting and postprandial glucose concentrations were higher in the diabetic than nondiabetic subjects. Although peak insulin secretion was delayed (P < 0.001) and lower (P < 0.05) in type 2 diabetes, the integrated total postprandial insulin response did not differ between groups. Insulin action, insulin secretion, disposition indexes, and glucose effectiveness all were lower (P < 0.05) in diabetic than in nondiabetic subjects. Whereas the rate of meal glucose appearance did not differ between groups, the percent suppression of endogenous glucose production (EGP) was slightly delayed and the increment in glucose disappearance was substantially lower (P < 0.01) in diabetic subjects during the first 3 h after meal ingestion. Together, these defects resulted in an excessive rise in postprandial glucose concentrations in the diabetic subjects. CONCLUSIONS When measured using methods that avoid non-steady-state error, the rate of appearance of ingested glucose was normal and suppression of EGP was only minimally impaired. However, when considered in light of the prevailing glucose concentration, both were abnormal. In contrast, rates of postprandial glucose disappearance were substantially decreased due to defects in insulin secretion, insulin action, and glucose effectiveness.
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Affiliation(s)
- Ananda Basu
- Division of Endocrinology and Metabolism, Mayo Clinic College of Medicine, Rochester, Minnesota, USA.
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50
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Home PD, Pacini G. Hepatic dysfunction and insulin insensitivity in type 2 diabetes mellitus: a critical target for insulin-sensitizing agents. Diabetes Obes Metab 2008; 10:699-718. [PMID: 17825080 DOI: 10.1111/j.1463-1326.2007.00761.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The liver plays an essential role in maintaining glucose homeostasis, which includes insulin-mediated processes such as hepatic glucose output (HGO) and uptake, as well as in clearance of insulin itself. In type 2 diabetes, the onset of hyperglycaemia [itself a potent inhibitor of hepatic glucose output (HGO)], alongside hyperinsulinaemia, indicates the presence of hepatic insulin insensitivity. Increased HGO is central to the onset of hyperglycaemia and highlights the need to target hepatic insulin insensitivity as a central component of glucose-lowering therapy. The mechanisms underlying the development of hepatic insulin insensitivity are not well understood, but may be influenced by factors such as fatty acid oversupply and altered adipocytokine release from dysfunctional adipose tissue and increased liver fat content. Furthermore, although the impact of insulin insensitivity as a marker of cardiovascular disease is well known, the specific role of hepatic insulin insensitivity is less clear. The pharmacological tools available to improve insulin sensitivity include the biguanides (metformin) and thiazolidinediones (rosiglitazone and pioglitazone). Data from a number of sources indicate that thiazolidinediones, in particular, can improve multiple aspects of hepatic dysfunction, including reducing HGO, insulin insensitivity and liver fat content, as well as improving other markers of liver function and the levels of mediators with potential involvement in hepatic function, including fatty acids and adipocytokines. The current review addresses this topic from the perspective of the role of the liver in maintaining glucose homeostasis, its key involvement in the pathogenesis of type 2 diabetes and the tools currently available to reduce hepatic insulin insensitivity.
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Affiliation(s)
- P D Home
- School of Clinical Medical Sciences - Diabetes, The Medical School, University of Newcastle upon Tyne, Newcastle upon Tyne, UK.
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