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Adams JD, Egan AM, Laurenti MC, Schembri Wismayer D, Bailey KR, Cobelli C, Dalla Man C, Vella A. The Effect of Diabetes-Associated Variation in TCF7L2 on Postprandial Glucose Metabolism When Glucagon and Insulin Concentrations Are Matched. Metab Syndr Relat Disord 2022; 20:329-335. [PMID: 35442800 PMCID: PMC9419949 DOI: 10.1089/met.2021.0136] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Background: The rs7903146 variant in the TCF7L2 gene is associated with defects in postprandial insulin and glucagon secretion and increased risk of type 2 diabetes. However, it is unclear if this variant has effects on glucose metabolism that are independent of islet function. Methods: We studied 54 nondiabetic subjects on two occasions where endogenous hormone secretion was inhibited by somatostatin. Twenty-nine subjects were homozygous for the diabetes-associated allele (TT) and 25 for the diabetes-protective allele (CC) at rs7903146, but otherwise matched for anthropometric characteristics. On 1 day, glucagon infused at a rate of 0.65 ng/kg/min, and at 0 min prevented a fall in glucagon (nonsuppressed day). On the contrary, infusion commenced at 120 min to create a transient fall in glucagon (suppressed day). Subjects received glucose (labeled with [3-3H]-glucose) infused to mimic the systemic appearance of oral glucose. Insulin was infused to mimic a prandial insulin response. Endogenous glucose production (EGP) was measured using the tracer dilution technique. Results: Lack of glucagon suppression increased postchallenge glucose concentrations and impaired EGP suppression. However, in the presence of matched insulin and glucagon concentrations, genetic variation in TCF7L2 did not alter glucose metabolism. Conclusion: These data suggest that genetic variation in TCF7L2 alters glucose metabolism through changes in islet hormone secretion.
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Affiliation(s)
- Jon D Adams
- Division of Endocrinology, Diabetes and Metabolism, Mayo Clinic College of Medicine, Rochester, Minnesota, USA
| | - Aoife M Egan
- Division of Endocrinology, Diabetes and Metabolism, Mayo Clinic College of Medicine, Rochester, Minnesota, USA
| | - Marcello C Laurenti
- Division of Endocrinology, Diabetes and Metabolism, Mayo Clinic College of Medicine, Rochester, Minnesota, USA
| | - Daniel Schembri Wismayer
- Division of Endocrinology, Diabetes and Metabolism, Mayo Clinic College of Medicine, Rochester, Minnesota, USA
| | - Kent R Bailey
- Division of Biomedical Statistics and Informatics, Mayo Clinic, Rochester, Minnesota, USA
| | - Claudio Cobelli
- Department of Woman and Child's Health and University of Padova, Padova, Italy
| | - Chiara Dalla Man
- Department of Information Engineering, University of Padova, Padova, Italy
| | - Adrian Vella
- Division of Endocrinology, Diabetes and Metabolism, Mayo Clinic College of Medicine, Rochester, Minnesota, USA
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2
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Shah M, Laurenti MC, Dalla Man C, Ma J, Cobelli C, Rizza RA, Vella A. Contribution of endogenous glucagon-like peptide-1 to changes in glucose metabolism and islet function in people with type 2 diabetes four weeks after Roux-en-Y gastric bypass (RYGB). Metabolism 2019; 93:10-17. [PMID: 30586575 PMCID: PMC6401231 DOI: 10.1016/j.metabol.2018.12.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Revised: 12/07/2018] [Accepted: 12/20/2018] [Indexed: 01/03/2023]
Abstract
UNLABELLED Glucagon-Like Peptide-1 (GLP-1) is an insulin secretagogue which is elevated after Roux-en-Y Gastric Bypass (RYGB). However, its contribution to glucose metabolism after RYGB remains uncertain. AIMS We tested the hypothesis that GLP-1 lowers postprandial glucose concentrations and improves β-cell function after RYGB. MATERIALS AND METHODS To address these questions we used a labeled mixed meal to assess glucose metabolism and islet function in 12 obese subjects with type 2 diabetes studied before and four weeks after RYGB. During the post-RYGB study subjects were randomly assigned to receive an infusion of either saline or Exendin-9,39 a competitive antagonist of GLP-1 at its receptor. Exendin-9,39 was infused at 300 pmol/kg/min for 6 h. All subjects underwent RYGB for medically-complicated obesity. RESULTS Exendin-9,39 resulted in increased integrated incremental postprandial glucose concentrations (181 ± 154 vs. 582 ± 129 mmol per 6 h, p = 0.02). In contrast, this was unchanged in the presence of saline (275 ± 88 vs. 315 ± 66 mmol per 6 h, p = 0.56) after RYGB. Exendin-9,39 also impaired β-cell responsivity to glucose but did not alter Disposition Index (DI). CONCLUSIONS These data indicate that the elevated GLP-1 concentrations that occur early after RYGB improve postprandial glucose tolerance by enhancing postprandial insulin secretion.
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Affiliation(s)
- Meera Shah
- Division of Endocrinology, Diabetes & Metabolism, Mayo Clinic College of Medicine, 200 First Street SW, Rochester, MN 55905, USA.
| | - Marcello C Laurenti
- Department of Information Engineering, University of Padua, Via Gradenigo 6A, Padua 35131, Italy.
| | - Chiara Dalla Man
- Department of Information Engineering, University of Padua, Via Gradenigo 6A, Padua 35131, Italy.
| | - Jing Ma
- Division of Endocrinology, Diabetes & Metabolism, Mayo Clinic College of Medicine, 200 First Street SW, Rochester, MN 55905, USA.
| | - Claudio Cobelli
- Department of Information Engineering, University of Padua, Via Gradenigo 6A, Padua 35131, Italy.
| | - Robert A Rizza
- Division of Endocrinology, Diabetes & Metabolism, Mayo Clinic College of Medicine, 200 First Street SW, Rochester, MN 55905, USA.
| | - Adrian Vella
- Division of Endocrinology, Diabetes & Metabolism, Mayo Clinic College of Medicine, 200 First Street SW, Rochester, MN 55905, USA.
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3
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Quilliot D, Malgras A, Paquot N, Ziegler O. Diabète et nutrition artificielle : principes de prise en charge. NUTR CLIN METAB 2013. [DOI: 10.1016/j.nupar.2013.09.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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4
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Jauslin PM, Frey N, Karlsson MO. Modeling of 24-Hour Glucose and Insulin Profiles of Patients With Type 2 Diabetes. J Clin Pharmacol 2013; 51:153-64. [DOI: 10.1177/0091270010362536] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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5
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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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6
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Moore MC, Coate KC, Winnick JJ, An Z, Cherrington AD. Regulation of hepatic glucose uptake and storage in vivo. Adv Nutr 2012; 3:286-94. [PMID: 22585902 PMCID: PMC3649460 DOI: 10.3945/an.112.002089] [Citation(s) in RCA: 229] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
In the postprandial state, the liver takes up and stores glucose to minimize the fluctuation of glycemia. Elevated insulin concentrations, an increase in the load of glucose reaching the liver, and the oral/enteral/portal vein route of glucose delivery (compared with the peripheral intravenous route) are factors that increase the rate of net hepatic glucose uptake (NHGU). The entry of glucose into the portal vein stimulates a portal glucose signal that not only enhances NHGU but concomitantly reduces muscle glucose uptake to ensure appropriate partitioning of a glucose load. This coordinated regulation of glucose uptake is likely neurally mediated, at least in part, because it is not observed after total hepatic denervation. Moreover, there is evidence that both the sympathetic and the nitrergic innervation of the liver exert a tonic repression of NHGU that is relieved under feeding conditions. Further, the energy sensor 5'AMP-activated protein kinase appears to be involved in regulation of NHGU and glycogen storage. Consumption of a high-fat and high-fructose diet impairs NHGU and glycogen storage in association with a reduction in glucokinase protein and activity. An understanding of the impact of nutrients themselves and the route of nutrient delivery on liver carbohydrate metabolism is fundamental to the development of therapies for impaired postprandial glucoregulation.
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Affiliation(s)
- Mary Courtney Moore
- Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine, Nashville, TN
| | - Katie C. Coate
- Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine, Nashville, TN,current address: Howard Hughes Medical Institute, Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX
| | - Jason J. Winnick
- Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine, Nashville, TN
| | - Zhibo An
- Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine, Nashville, TN,current address: Department of Medicine, Division of Endocrinology, University of Cincinnati Medical Center, Cincinnati, OH
| | - Alan D. Cherrington
- Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine, Nashville, TN
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7
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Quilliot D, Malgras A, Zallot C, Ziegler O. Incrétines et nutrition entérale. MEDECINE INTENSIVE REANIMATION 2011. [DOI: 10.1007/s13546-011-0287-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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8
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Vella A, Rizza RA. Application of isotopic techniques using constant specific activity or enrichment to the study of carbohydrate metabolism. Diabetes 2009; 58:2168-74. [PMID: 19794073 PMCID: PMC2750215 DOI: 10.2337/db09-0318] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Adrian Vella
- Division of Endocrinology, Diabetes, Metabolism, and Nutrition, Mayo Clinic, Rochester, Minnesota, USA.
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Jauslin PM, Silber HE, Frey N, Gieschke R, Simonsson USH, Jorga K, Karlsson MO. An integrated glucose-insulin model to describe oral glucose tolerance test data in type 2 diabetics. J Clin Pharmacol 2007; 47:1244-55. [PMID: 17906159 DOI: 10.1177/0091270007302168] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
An integrated model for the glucose-insulin system describing oral glucose tolerance test data was developed, extending on a previously introduced model for intravenous glucose provocations. Model extensions comprised the description of glucose absorption by a chain of transit compartments with a mean transit time of 35 minutes, a bioavailability of 80%, and a representation of the incretin effect, expressed as a direct effect of the glucose absorption rate on insulin secretion. The ability of the model to predict the incretin effect was assessed by simulating the observed difference in insulin response following an oral glucose tolerance test compared with an isoglycemic glucose infusion mimicking an oral glucose tolerance test profile. The extension of the integrated glucose-insulin model to gain information from oral glucose tolerance test data considerably expands its range of applications because the oral glucose tolerance test is one of the most common glucose challenge experiments for assessing the efficacy of hypoglycemic agents in clinical drug development.
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Affiliation(s)
- Petra M Jauslin
- Department of Pharmaceutical Biosciences, Division of Pharmacokinetics and Drug Therapy, University of Uppsala, Friggs Grand 4, Halmstad, Sweden
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Klinke DJ. Integrating Epidemiological Data into a Mechanistic Model of Type 2 Diabetes: Validating the Prevalence of Virtual Patients. Ann Biomed Eng 2007; 36:321-34. [DOI: 10.1007/s10439-007-9410-y] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2007] [Accepted: 11/16/2007] [Indexed: 01/09/2023]
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11
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Chueh FY, Malabanan C, McGuinness OP. Impact of portal glucose delivery on glucose metabolism in conscious, unrestrained mice. Am J Physiol Endocrinol Metab 2006; 291:E1206-11. [PMID: 16822956 DOI: 10.1152/ajpendo.00608.2005] [Citation(s) in RCA: 9] [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: 11/22/2022]
Abstract
Previous studies in mice suggest that portal venous infusion of glucose at a low rate paradoxically causes hypoglycemia; this does not occur in dogs, rats, and humans. A possible explanation is that fasting status in the mouse studies may have altered the response. We sought to determine whether the response to portal glucose delivery in the mouse was similar to that seen in other species and whether it was dependent on fasting status. Studies were performed on chronically catheterized conscious mice. Catheters were placed into the portal and jugular veins and carotid artery 5 days before study. After a 5- or 16-h fast, glucose was infused into either the portal (PO) or the jugular vein (JU) for 6 h at 25 microg.g(-1).min(-1). [3-(3)H]glucose was infused into the JU to measure glucose turnover. In 5-h-fasted mice, PO and JU exhibited similar increases in arterial blood glucose from 155 +/- 11 to 173 +/- 19 and 147 +/- 8 to 173 +/- 10 mg/dl, respectively. Endogenous glucose production decreased and arterial insulin increased to the same extent in both PO and JU. A similar response was observed in 16-h-fasted mice; however, the proportion of hepatic glycogen synthesis occurring by the indirect pathway was increased by fasting. In summary, portal glucose delivery in the mouse did not cause hypoglycemia even when the duration of the fast was extended. The explanation of the differing response from previous reports in the mouse is unclear.
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Affiliation(s)
- Fu-Yu Chueh
- Dept. of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232-0615, USA
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12
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Abstract
PURPOSE OF REVIEW The development of incretin hormones and incretin analogues for the therapy of diabetes highlights the importance of the gastrointestinal tract in the maintenance of glucose tolerance. RECENT FINDINGS The review focuses on recent information on the role of incretins and their breakdown products on insulin secretion, gastric emptying, and satiety. The importance of gastric emptying and its absorptive potential as well as of dietary composition on gastric emptying and glucose tolerance is highlighted. The concept of a portal glucose sensor in humans has been the subject of some controversy but has been recently revisited. SUMMARY The gastrointestinal tract plays an important part in glucose tolerance. In this review we have examined how factors altering gastric emptying, insulin secretion in response to meal ingestion, and gastric emptying contribute to the maintenance and deterioration of glucose tolerance.
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Affiliation(s)
- Adrian Vella
- Division of Endocrinology & Metabolism, Department of Medicine, Mayo Clinic & Foundation, 200 First ST SW, Rochester, MN 55905, USA.
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13
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Féry F, Tappy L, Devière J, Balasse EO. Comparison of intraduodenal and intravenous glucose metabolism under clamp conditions in humans. Am J Physiol Endocrinol Metab 2004; 286:E176-83. [PMID: 14532166 DOI: 10.1152/ajpendo.00201.2003] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
To determine whether the uptake and metabolic partition of glucose are influenced by its delivery route, 12 normal volunteers underwent two 3-h euglycemic (approximately 93 mg/dl) hyperinsulinemic (approximately 43 mU/l) clamps at a 3- to 5-wk interval, one with intravenous (i.v.) and the other with intraduodenal (i.d.) glucose labeled with [3-3H]- and [U-14C]glucose. Systemic glucose was traced with [6,6-2H2]glucose in eight subjects. During the last hour of the clamps, the average glucose infusion rate (5.85 +/- 0.37 vs. 5.43 +/- 0.43 mg.kg(-1).min(-1); P = 0.02) and exogenous glucose uptake (5.66 +/- 0.37 vs. 5.26 +/- 0.41 mg.kg(-1).min(-1); P = 0.04) were borderline higher in the i.d. than in the i.v. studies. The increased uptake was entirely accounted for by increased glycolysis (3H2O production), which was attributed to the stimulation of gut metabolism by the absorptive process. No difference was observed in glucose storage whether it was calculated as glucose uptake minus glycolysis (i.d. vs. i.v.: 2.44 +/- 0.28 vs. 2.40 +/- 0.31 mg.kg(-1).min(-1)) or as glucose uptake minus net glucose oxidation (2.86 +/- 0.33 vs. 2.81 +/- 0.35 mg.kg(-1).min(-1)). Because peripheral tissues were exposed to identical glucose, insulin, and free fatty acid levels under the two experimental conditions, we assumed that their glucose uptake and storage were similar during the two tests. We therefore suggest that hepatic glycogen storage (estimated as whole body minus peripheral storage) was also unaffected by the route of glucose delivery. On the other hand, in the i.d. tests, the glucose splanchnic extraction ratio calculated by the dual-isotope technique averaged 4.9 +/- 2.3%, which is close to the figures published for i.v. glucose. Despite the limitations related to whole body measurements, these two sets of data do not support the idea that enteral glucose stimulates hepatic uptake more efficiently than i.v. glucose.
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Affiliation(s)
- F Féry
- Laboratory of Experimental Medicine, Hôpital Erasme, Brussels Free University, B-1070 Brussels, Belgium.
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Moore MC, Cherrington AD, Wasserman DH. Regulation of hepatic and peripheral glucose disposal. Best Pract Res Clin Endocrinol Metab 2003; 17:343-64. [PMID: 12962690 DOI: 10.1016/s1521-690x(03)00036-8] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Precise regulation of hepatic and peripheral glucose uptake is essential to preserve glucose homeostasis. The liver extracts approximately 1/3 of an oral glucose load, skeletal muscle extracts approximately 1/3, and other tissues, particularly the central nervous system and the formed elements of the blood, take up the balance. The load of glucose reaching the liver, the insulin concentration, and the route of glucose delivery (the hepatic portal or a peripheral vein) are key determinants of the rate of net hepatic glucose uptake. Glucose uptake by muscle requires three steps: delivery of glucose from the blood to the muscle, transport of glucose across the muscle membrane, and phosphorylation of glucose, processes affected by glycaemia and insulinaemia. Exercise stimulates insulin-dependent and -independent muscle glucose uptake, as well as the liver's ability to take up glucose.
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Affiliation(s)
- Mary Courtney Moore
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, 702 Light Hall, Nashville, TN 37232-0615, USA
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Zangeneh F, Basu R, Shah P, Arora P, Camilleri M, Rizza RA. Enteral infusion of glucose at rates approximating EGP enhances glucose disposal but does not cause hypoglycemia. Am J Physiol Endocrinol Metab 2003; 285:E280-6. [PMID: 12857674 DOI: 10.1152/ajpendo.00055.2003] [Citation(s) in RCA: 10] [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: 12/21/2022]
Abstract
Portal infusion of glucose at rates approximating endogenous glucose production (EGP) causes paradoxical hypoglycemia in wild-type but not GLUT2 null mice, implying activation of a specific portal glucose sensor. To determine whether this occurs in humans, glucose containing [3-3H]glucose was infused intraduodenally at rates of 3.1 mg. kg-1. min-1 (n = 5), 1.55 mg. kg-1. min-1 (n = 9), or 0/0.1 mg. kg-1. min-1 (n = 9) for 7 h in healthy nondiabetic subjects. [6,6-2H2]glucose was infused intravenously to enable simultaneous measurement of EGP, glucose disappearance, and the rate of appearance of the intraduodenally infused glucose. Plasma glucose concentrations fell (P < 0.01) from 90 +/- 1 to 84 +/- 2 mg/dl during the 0/0.1 mg. kg-1. min-1 id infusions but increased (P < 0.001) to 104 +/- 5 and 107 +/- 3 mg/dl, respectively, during the 1.55 and 3.1 mg. kg-1. min-1 id infusions. In contrast, insulin increased (P < 0.05) during the 1.55 and 3.0 mg. kg-1. min-1 infusions, reaching a peak of 10 +/- 2 and 18 +/- 5 micro U/ml, respectively, by 2 h. Insulin concentrations then fell back to concentrations that no longer differed by study end (7 +/- 1 vs. 8 +/- 1 micro U/ml). This resulted in comparable suppression of EGP by study end (0.84 +/- 0.2 and 0.63 +/- 0.1 mg. kg-1. min-1). Glucose disappearance was higher (P < 0.01) during the final hour of the 3.1 than 1.55 mg. kg-1. min-1 id infusion (4.47 +/- 0.2 vs. 2.6 +/- 0.1 mg. kg-1. min-1), likely because of the slightly, but not significantly, higher glucose and insulin concentrations. We conclude that, in contrast to mice, selective portal glucose delivery at rates approximating EGP does not cause hypoglycemia in humans.
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Affiliation(s)
- Farhad Zangeneh
- Mayo Clinic Rochester, 200 1st St., SW, Rm. 5-194 Joseph, Rochester, MN 55905, USA
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