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Ahrén B. Glucagon-like peptide-1 and beta cell glucose sensitivity - a glucose ramp study in mice. Peptides 2021; 146:170650. [PMID: 34547355 DOI: 10.1016/j.peptides.2021.170650] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 09/09/2021] [Accepted: 09/16/2021] [Indexed: 01/03/2023]
Abstract
The incretin glucagon-like peptide-1 (GLP-1) is a gut hormone but also locally produced in pancreatic islets. We evaluated effects of GLP-1 on the insulin response to a gradual increase in glucose in mice within physiological levels. We initially developed a glucose ramp technique in mice. Glucose levels were slowly increased by 0.2 mmol/l/min for 40 min under control conditions, during intravenous infusion of GLP-1 and in GLP-1 receptor knockout mice. In control mice, glucose levels increased from 8.5 ± 0.3 to 16.1 ± 0.3 mmol/l over the 40 min, i.e., by 0.22 ± 0.01 mmol/l/min. This resulted in a slow increase in insulin levels by 96 ± 38 pmol/l from the baseline of 319 ± 53 pmol/l. GLP-1 at 0.5 nmol/kg as bolus plus 0.3 nmol/kg/min over 40 min progressively increased this insulin response by 100-fold, to 9.5 ± 0.2 nmol/l (P < 0.001). Higher doses of GLP-1 enhanced the insulin response similarly (1.0 or 3.0 nmol/kg bolus followed by 0.4 or 1.2 nmol/kg/min), whereas a lower dose (0.3 nmol/kg bolus plus 0.15 nmol/kg/min) had no significant effect compared to controls. Moreover, there was no significant difference in insulin responses between controls and GLP-1 receptor knockout mice. Since the increase in glucose levels were standardized, there was no significant difference in glucose levels between the experimental groups. We conclude that the glucose ramp technique is a tool for studies on insulin responses to slow changes in circulating glucose levels in mice. We also conclude that GLP-1 is extraordinarily potent in enhancing the insulin response to a slow increase in glucose levels.
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Affiliation(s)
- Bo Ahrén
- Department of Clinical Sciences Lund, Lund University, Lund, Sweden.
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2
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Jaffredo M, Bertin E, Pirog A, Puginier E, Gaitan J, Oucherif S, Lebreton F, Bosco D, Catargi B, Cattaert D, Renaud S, Lang J, Raoux M. Dynamic Uni- and Multicellular Patterns Encode Biphasic Activity in Pancreatic Islets. Diabetes 2021; 70:878-888. [PMID: 33468514 DOI: 10.2337/db20-0214] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Accepted: 01/11/2021] [Indexed: 11/13/2022]
Abstract
Biphasic secretion is an autonomous feature of many endocrine micro-organs to fulfill physiological demands. The biphasic activity of islet β-cells maintains glucose homeostasis and is altered in type 2 diabetes. Nevertheless, underlying cellular or multicellular functional organizations are only partially understood. High-resolution noninvasive multielectrode array recordings permit simultaneous analysis of recruitment, of single-cell, and of coupling activity within entire islets in long-time experiments. Using this unbiased approach, we addressed the organizational modes of both first and second phase in mouse and human islets under physiological and pathophysiological conditions. Our data provide a new uni- and multicellular model of islet β-cell activation: during the first phase, small but highly active β-cell clusters are dominant, whereas during the second phase, electrical coupling generates large functional clusters via multicellular slow potentials to favor an economic sustained activity. Postprandial levels of glucagon-like peptide 1 favor coupling only in the second phase, whereas aging and glucotoxicity alter coupled activity in both phases. In summary, biphasic activity is encoded upstream of vesicle pools at the micro-organ level by multicellular electrical signals and their dynamic synchronization between β-cells. The profound alteration of the electrical organization of islets in pathophysiological conditions may contribute to functional deficits in type 2 diabetes.
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Affiliation(s)
- Manon Jaffredo
- University of Bordeaux, CNRS, Institute of Chemistry and Biology of Membranes and Nano-objects, UMR 5248, Pessac, France
| | - Eléonore Bertin
- University of Bordeaux, CNRS, Institute of Chemistry and Biology of Membranes and Nano-objects, UMR 5248, Pessac, France
| | - Antoine Pirog
- University of Bordeaux, CNRS, Institut National Polytechnique de Bordeaux, Laboratoire de l'Intégration du Matériau au Système, UMR 5218, Talence, France
| | - Emilie Puginier
- University of Bordeaux, CNRS, Institute of Chemistry and Biology of Membranes and Nano-objects, UMR 5248, Pessac, France
| | - Julien Gaitan
- University of Bordeaux, CNRS, Institute of Chemistry and Biology of Membranes and Nano-objects, UMR 5248, Pessac, France
| | - Sandra Oucherif
- University of Bordeaux, CNRS, Institute of Chemistry and Biology of Membranes and Nano-objects, UMR 5248, Pessac, France
| | - Fanny Lebreton
- Cell Isolation and Transplantation Center, Department of Surgery, Geneva University Hospitals, University of Geneva, Geneva, Switzerland
| | - Domenico Bosco
- Cell Isolation and Transplantation Center, Department of Surgery, Geneva University Hospitals, University of Geneva, Geneva, Switzerland
| | - Bogdan Catargi
- University of Bordeaux, CNRS, Institute of Chemistry and Biology of Membranes and Nano-objects, UMR 5248, Pessac, France
- University of Bordeaux, Hôpital Saint-André, Endocrinology and Metabolic Diseases, Bordeaux, France
| | - Daniel Cattaert
- University of Bordeaux, CNRS, Aquitaine Institute for Cognitive and Integrative Neuroscience, UMR 5287, Bordeaux, France
| | - Sylvie Renaud
- University of Bordeaux, CNRS, Institut National Polytechnique de Bordeaux, Laboratoire de l'Intégration du Matériau au Système, UMR 5218, Talence, France
| | - Jochen Lang
- University of Bordeaux, CNRS, Institute of Chemistry and Biology of Membranes and Nano-objects, UMR 5248, Pessac, France
| | - Matthieu Raoux
- University of Bordeaux, CNRS, Institute of Chemistry and Biology of Membranes and Nano-objects, UMR 5248, Pessac, France
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3
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Dimitriadis GD, Maratou E, Kountouri A, Board M, Lambadiari V. Regulation of Postabsorptive and Postprandial Glucose Metabolism by Insulin-Dependent and Insulin-Independent Mechanisms: An Integrative Approach. Nutrients 2021; 13:E159. [PMID: 33419065 PMCID: PMC7825450 DOI: 10.3390/nu13010159] [Citation(s) in RCA: 70] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 12/18/2020] [Accepted: 12/24/2020] [Indexed: 12/18/2022] Open
Abstract
Glucose levels in blood must be constantly maintained within a tight physiological range to sustain anabolism. Insulin regulates glucose homeostasis via its effects on glucose production from the liver and kidneys and glucose disposal in peripheral tissues (mainly skeletal muscle). Blood levels of glucose are regulated simultaneously by insulin-mediated rates of glucose production from the liver (and kidneys) and removal from muscle; adipose tissue is a key partner in this scenario, providing nonesterified fatty acids (NEFA) as an alternative fuel for skeletal muscle and liver when blood glucose levels are depleted. During sleep at night, the gradual development of insulin resistance, due to growth hormone and cortisol surges, ensures that blood glucose levels will be maintained within normal levels by: (a) switching from glucose to NEFA oxidation in muscle; (b) modulating glucose production from the liver/kidneys. After meals, several mechanisms (sequence/composition of meals, gastric emptying/intestinal glucose absorption, gastrointestinal hormones, hyperglycemia mass action effects, insulin/glucagon secretion/action, de novo lipogenesis and glucose disposal) operate in concert for optimal regulation of postprandial glucose fluctuations. The contribution of the liver in postprandial glucose homeostasis is critical. The liver is preferentially used to dispose over 50% of the ingested glucose and restrict the acute increases of glucose and insulin in the bloodstream after meals, thus protecting the circulation and tissues from the adverse effects of marked hyperglycemia and hyperinsulinemia.
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Affiliation(s)
- George D. Dimitriadis
- Sector of Medicine, Medical School, National and Kapodistrian University of Athens, 15772 Athens, Greece
| | - Eirini Maratou
- Department of Clinical Biochemistry, Medical School, National and Kapodistrian University of Athens, 15772 Athens, Greece;
- Department of Clinical Biochemistry, Medical School, “Attikon” University Hospital, Rimini 1, 12462 Chaidari, Greece
| | - Aikaterini Kountouri
- Research Institute and Diabetes Center, 2nd Department of Internal Medicine, “Attikon” University Hospital, 1 Rimini Street, 12542 Haidari, Greece; (A.K.); (V.L.)
| | - Mary Board
- St. Hilda’s College, University of Oxford, Cowley, Oxford OX4 1DY, UK;
| | - Vaia Lambadiari
- Research Institute and Diabetes Center, 2nd Department of Internal Medicine, “Attikon” University Hospital, 1 Rimini Street, 12542 Haidari, Greece; (A.K.); (V.L.)
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Schneider EL, Reid R, Parkes DG, Lutz TA, Ashley GW, Santi DV. A once-monthly GLP-1 receptor agonist for treatment of diabetic cats. Domest Anim Endocrinol 2020; 70:106373. [PMID: 31479925 DOI: 10.1016/j.domaniend.2019.07.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 06/28/2019] [Accepted: 07/01/2019] [Indexed: 12/23/2022]
Abstract
There is growing evidence that peptidic glucagon-like peptide-1 receptor agonists (GLP-1RA), such as exenatide, may provide useful therapeutic options for treatment of feline diabetes. However, because such drugs are administered subcutaneously, it is desirable that they be long-acting and not require frequent injections. We have developed a chemically controlled delivery system to support half-life extension of peptidic therapeutics. Here, the peptide is covalently attached to hydrogel microspheres by a self-cleaving β-eliminative linker; after subcutaneous injection of the microspheres, the peptide is slowly released from the depot to the systemic circulation. Using this technology, we developed a delivery system that supports once-monthly administration of a stable exenatide analog, [Gln28]exenatide, in rodents (Schneider, et al, ACS Chem Biol 12, 2107 to 2116, 2017). The purposes of the present study were a) to demonstrate pharmacokinetic and pharmacodynamic similarities of the deamidation-sensitive GLP-1RA exenatide and the closely related, more stable [Gln28]exenatide and b) to develop a long-acting GLP-1RA in cats. The results show that exenatide and [Gln28]exenatide injected intravenously or subcutaneously at 10 μg/kg have nearly identical pharmacokinetics in the cat-both having elimination half-lives of ∼40 min-but subcutaneously administered [Gln28]exenatide has superior bioavailability-93% for [Gln28]exenatide vs 52% for exenatide. The results also show that exenatide and [Gln28]exenatide have similar insulinotropic activities in the cat during a high-dose intravenous glucose tolerance test; they increased the area under the curve (AUC) for insulin to a similar extent but had no effect on glucose AUC. Finally, subcutaneous injection of a microsphere-[Gln28]exenatide conjugate containing an appropriate self-cleaving linker in the cat provides plasma [Gln28]exenatide with a half-life of about 40 d vs 40 min with the injected free peptide. Hence, the large body of information available for exenatide can be used to facilitate clinical development of [Gln28]exenatide as a treatment for feline diabetes, and the microsphere-[Gln28]exenatide conjugate is quite suitable for once-monthly subcutaneous administration of the peptide in the cat.
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Affiliation(s)
| | - R Reid
- ProLynx, San Francisco, CA, USA
| | | | - T A Lutz
- University of Zurich, Institute of Veterinary Physiology, Zurich, Switzerland
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Boland BB, Brown C, Boland ML, Cann J, Sulikowski M, Hansen G, Grønlund RV, King W, Rondinone C, Trevaskis J, Rhodes CJ, Grimsby JS. Pancreatic β-Cell Rest Replenishes Insulin Secretory Capacity and Attenuates Diabetes in an Extreme Model of Obese Type 2 Diabetes. Diabetes 2019; 68:131-140. [PMID: 30305366 DOI: 10.2337/db18-0304] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Accepted: 09/27/2018] [Indexed: 11/13/2022]
Abstract
The onset of common obesity-linked type 2 diabetes (T2D) is marked by exhaustive failure of pancreatic β-cell functional mass to compensate for insulin resistance and increased metabolic demand, leading to uncontrolled hyperglycemia. Here, the β-cell-deficient obese hyperglycemic/hyperinsulinemic KS db/db mouse model was used to assess consequential effects on β-cell functional recovery by lowering glucose homeostasis and/or improving insulin sensitivity after treatment with thiazolidinedione therapy or glucagon-like peptide 1 receptor agonism alone or in combination with sodium/glucose cotransporter 2 inhibition (SGLT-2i). SGLT-2i combination therapies improved glucose homeostasis, independent of changes in body weight, resulting in a synergistic increase in pancreatic insulin content marked by significant recovery of the β-cell mature insulin secretory population but with limited changes in β-cell mass and no indication of β-cell dedifferentiation. Restoration of β-cell insulin secretory capacity also restored biphasic insulin secretion. These data emphasize that by therapeutically alleviating the demand for insulin in vivo, irrespective of weight loss, endogenous β-cells recover significant function that can contribute to attenuating diabetes. Thus, this study provides evidence that alleviation of metabolic demand on the β-cell, rather than targeting the β-cell itself, could be effective in delaying the progression of T2D.
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Affiliation(s)
- Brandon B Boland
- Division of Cardiovascular and Metabolic Disease, MedImmune LLC, Gaithersburg, MD
- Gubra ApS, Hørsholm, Denmark
| | - Charles Brown
- Division of Cardiovascular and Metabolic Disease, MedImmune LLC, Gaithersburg, MD
| | - Michelle L Boland
- Division of Cardiovascular and Metabolic Disease, MedImmune LLC, Gaithersburg, MD
- Gubra ApS, Hørsholm, Denmark
| | - Jennifer Cann
- Division of Cardiovascular and Metabolic Disease, MedImmune LLC, Gaithersburg, MD
| | - Michal Sulikowski
- Division of Cardiovascular and Metabolic Disease, MedImmune LLC, Gaithersburg, MD
| | | | | | - Wanda King
- Division of Cardiovascular and Metabolic Disease, MedImmune LLC, Gaithersburg, MD
| | - Cristina Rondinone
- Division of Cardiovascular and Metabolic Disease, MedImmune LLC, Gaithersburg, MD
| | - James Trevaskis
- Division of Cardiovascular and Metabolic Disease, MedImmune LLC, Gaithersburg, MD
| | - Christopher J Rhodes
- Division of Cardiovascular and Metabolic Disease, MedImmune LLC, Gaithersburg, MD
| | - Joseph S Grimsby
- Division of Cardiovascular and Metabolic Disease, MedImmune LLC, Gaithersburg, MD
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6
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Co-Ingestion of Rice Bran Soymilk or Plain Soymilk with White Bread: Effects on the Glycemic and Insulinemic Response. Nutrients 2018; 10:nu10040449. [PMID: 29617350 PMCID: PMC5946234 DOI: 10.3390/nu10040449] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Revised: 03/29/2018] [Accepted: 04/03/2018] [Indexed: 02/07/2023] Open
Abstract
The regular consumption of soy products is associated with inverse incidence of type 2 diabetes, and there has been an increasing interest in the glycemia reducing potential of rice bran and its components. In this study, we investigated whether consuming soymilk with the addition of rice bran (fiber) can reduce the glycemic response of a carbohydrate meal. Seventeen healthy Asian men (BMI: 18.5–29 kg/m2) participated in this randomized crossover trial. On four occasions, they consumed white bread (two times) and white bread with two different soymilks differing in protein and rice bran content. Blood samples were taken to measure glucose and insulin response over a period of 3 hours. Taking the glycemic index (GI) value of white bread as a reference value of 100, the GI of white bread when co-ingested with rice bran soymilk (RBS) was 83.1 (±7.7) and sugar-free soymilk (SFS) was 77.5 (±10.1), both were lower than white bread (p < 0.05). The insulin response of both soymilk treatments was similar to white bread (p > 0.05). The glucose/insulin ratio of RBS and SFS were respectively 43.1 (±6.1) and 60.0 (±17.0) and were lower (p < 0.05) than white bread (123.5 ± 21.1) during the first 30 min. In conclusion, co-ingestion of low amounts of soy protein with a carbohydrate meal stimulated early-phase insulin secretion and thereby increased blood glucose clearance effectiveness. Furthermore, rice bran-fortified soymilk reduced the glycemic response similarly to soymilk with a greater dose of soy protein. Rice bran and its components offer therapeutic potential for glycemic and insulinemic control.
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Luginbuhl KM, Schaal JL, Umstead B, Mastria EM, Li X, Banskota S, Arnold S, Feinglos M, D’Alessio D, Chilkoti A. One-week glucose control via zero-order release kinetics from an injectable depot of glucagon-like peptide-1 fused to a thermosensitive biopolymer. Nat Biomed Eng 2017; 1:0078. [PMID: 29062587 PMCID: PMC5650111 DOI: 10.1038/s41551-017-0078] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Accepted: 04/25/2017] [Indexed: 12/30/2022]
Abstract
Stimulation of the glucagon-like peptide-1 (GLP1) receptor is a useful treatment strategy for type 2 diabetes because of pleiotropic effects, including the regulation of islet hormones and the induction of satiety. However, the native ligand for the GLP1 receptor has a short half-live owing to enzymatic inactivation and rapid clearance. Here, we show that a subcutaneous depot formed after a single injection of GLP1 recombinantly fused to a thermosensitive elastin-like polypeptide results in zero-order release kinetics and circulation times of up to 10 days in mice and 17 days in monkeys. The optimized pharmacokinetics leads to 10 days of glycemic control in three different mouse models of diabetes, as well as to the reduction of glycosylated hemoglobin levels and weight gain in ob/ob mice treated once weekly for 8 weeks. Our results suggest that the optimized GLP1 formulation could enhance therapeutic outcomes by eliminating peak-and-valley pharmacokinetics and improving overall safety and tolerability. The design principles that we established should be broadly applicable for improving the pharmacological performance of other peptide and protein therapeutics.
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Affiliation(s)
- Kelli M. Luginbuhl
- Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708, USA
| | - Jeffrey L. Schaal
- Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708, USA
| | - Bret Umstead
- PhaseBio Pharmaceuticals, Inc., Malvern, Pennsylvania 19355, USA
| | - Eric M. Mastria
- Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708, USA
| | - Xinghai Li
- Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708, USA
| | - Samagya Banskota
- Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708, USA
| | - Susan Arnold
- PhaseBio Pharmaceuticals, Inc., Malvern, Pennsylvania 19355, USA
| | - Mark Feinglos
- Division of Endocrinology, Metabolism, and Nutrition, Duke University Medical Center, Durham, North Carolina 27710, USA
| | - David D’Alessio
- Division of Endocrinology, Metabolism, and Nutrition, Duke University Medical Center, Durham, North Carolina 27710, USA
| | - Ashutosh Chilkoti
- Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708, USA
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de la Peña A, Loghin C, Cui X, Zhang X, Kapitza C, Kelly RP. Once-weekly dulaglutide 1.5 mg restores insulin secretion in response to intravenous glucose infusion. Diabetes Obes Metab 2017; 19:517-523. [PMID: 27976833 DOI: 10.1111/dom.12847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Revised: 11/29/2016] [Accepted: 12/06/2016] [Indexed: 12/01/2022]
Abstract
AIMS To evaluate the effects of dulaglutide 1.5 mg on first- and second-phase insulin secretion in response to an intravenous (i.v.) glucose bolus challenge, in subjects with type 2 diabetes mellitus (T2DM; primary objective) and in healthy subjects. MATERIALS AND METHODS In this randomized, double-blind, placebo-controlled, 2-period crossover study, subjects received a single subcutaneous injection of dulaglutide 1.5 mg or placebo on day 1 of each period. On day 3, subjects underwent a 6-hour insulin infusion, followed by an i.v. glucose bolus and a glucagon challenge during hyperglycaemia. Areas under the concentration-time curve and maximum concentrations for first- (AUC0-10 and Cmax0-10 ) and second-phase secretion (AUC10-180 and Cmax10-180 ) were calculated for insulin and C-peptide. The glucose disappearance constant (Kg ) and homeostasis model assessment of β-cell function (HOMA-β) were assessed. RESULTS In 20 subjects with T2DM, dulaglutide increased mean insulin AUC0-10 by 7.92-fold and Cmax0-10 by 5.40-fold vs placebo, and mean AUC10-180 and Cmax10-180 by 2.44- and 3.78- fold, respectively. In 10 healthy subjects, dulaglutide increased the mean insulin AUC0-10 by 3.09-fold and Cmax0-10 by 2.96-fold vs placebo, and mean AUC10-180 and Cmax10-180 by 2.04- and 4.15-fold, respectively. The corresponding C-peptide values also increased. Mean Kg and HOMA-β were higher after dulaglutide compared with placebo. CONCLUSIONS In subjects with T2DM, a single dulaglutide 1.5-mg dose restored the first-phase insulin secretion in response to an i.v. glucose bolus, increased the second-phase insulin response and enhanced β-cell function.
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Affiliation(s)
| | | | - Xuewei Cui
- Eli Lilly and Company, Indianapolis, Indiana
| | - Xin Zhang
- Eli Lilly and Company, Indianapolis, Indiana
| | | | - Ronan P Kelly
- Lilly-NUS Centre for Clinical Pharmacology, Singapore
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Morettini M, Faelli E, Perasso L, Fioretti S, Burattini L, Ruggeri P, Di Nardo F. IVGTT-based simple assessment of glucose tolerance in the Zucker fatty rat: Validation against minimal models. PLoS One 2017; 12:e0173200. [PMID: 28264067 PMCID: PMC5338807 DOI: 10.1371/journal.pone.0173200] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Accepted: 02/16/2017] [Indexed: 12/29/2022] Open
Abstract
For the assessment of glucose tolerance from IVGTT data in Zucker rat, minimal model methodology is reliable but time- and money-consuming. This study aimed to validate for the first time in Zucker rat, simple surrogate indexes of insulin sensitivity and secretion against the glucose-minimal-model insulin sensitivity index (SI) and against first- (Φ1) and second-phase (Φ2) β-cell responsiveness indexes provided by C-peptide minimal model. Validation of the surrogate insulin sensitivity index (ISI) and of two sets of coupled insulin-based indexes for insulin secretion, differing from the cut-off point between phases (FPIR3-SPIR3, t = 3 min and FPIR5-SPIR5, t = 5 min), was carried out in a population of ten Zucker fatty rats (ZFR) and ten Zucker lean rats (ZLR). Considering the whole rat population (ZLR+ZFR), ISI showed a significant strong correlation with SI (Spearman's correlation coefficient, r = 0.88; P<0.001). Both FPIR3 and FPIR5 showed a significant (P<0.001) strong correlation with Φ1 (r = 0.76 and r = 0.75, respectively). Both SPIR3 and SPIR5 showed a significant (P<0.001) strong correlation with Φ2 (r = 0.85 and r = 0.83, respectively). ISI is able to detect (P<0.001) the well-recognized reduction in insulin sensitivity in ZFRs, compared to ZLRs. The insulin-based indexes of insulin secretion are able to detect in ZFRs (P<0.001) the compensatory increase of first- and second-phase secretion, associated to the insulin-resistant state. The ability of the surrogate indexes in describing glucose tolerance in the ZFRs was confirmed by the Disposition Index analysis. The model-based validation performed in the present study supports the utilization of low-cost, insulin-based indexes for the assessment of glucose tolerance in Zucker rat, reliable animal model of human metabolic syndrome.
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Affiliation(s)
- Micaela Morettini
- Department of Information Engineering, Università Politecnica delle Marche, Ancona, Italy
| | - Emanuela Faelli
- Department of Experimental Medicine, University of Genoa, Genoa, Italy
| | - Luisa Perasso
- Department of Experimental Medicine, University of Genoa, Genoa, Italy
| | - Sandro Fioretti
- Department of Information Engineering, Università Politecnica delle Marche, Ancona, Italy
| | - Laura Burattini
- Department of Information Engineering, Università Politecnica delle Marche, Ancona, Italy
| | - Piero Ruggeri
- Department of Experimental Medicine, University of Genoa, Genoa, Italy
| | - Francesco Di Nardo
- Department of Information Engineering, Università Politecnica delle Marche, Ancona, Italy
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10
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Campbell RK. Diabetes: Rationale for Dipeptidyl Peptidase 4 Inhibitors: A New Class of Oral Agents for the Treatment of Type 2 Diabetes Mellitus. Ann Pharmacother 2016; 41:51-60. [PMID: 17190843 DOI: 10.1345/aph.1h459] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Objective: To review advances in understanding the pathophysiologic basis of type 2 diabetes mellitus and the pharmacology and mechanism of action of dipeptidyl peptidase 4 (DPP-4) inhibition in correcting the underlying defects in glycemic control. Data Sources: Articles were identified through MEDLINE for the period 1966 through November 2006. Abstracts and presentations from the American Diabetes Association Scientific Sessions and the European Association for the Study of Diabetes (2002–2006) were also searched for scientific reports on DPP-4 inhibitors. Study Selection And Data Extraction: Abstracts, original clinical and preclinical research reports, and review articles published in the English language were identified for review. Literature discussing glucose regulation, incretin hormones, type 2 diabetes pathophysiology, and DPP-4 inhibition were evaluated and selected based on consideration of their support for the proof of concept, mechanistic and in vivo findings, and timeliness. Data Synthesis: The search for new and effective therapies for type 2 diabetes has led to the identification of a novel therapeutic target, the incretin hormones, which play a role in mediating glucose homeostasis via effects on glucagon and insulin secretion from pancreatic islet α- and β-cells, respectively. The incretins' glucagon-like peptide-1 and glucose-dependent insulinotropic polypeptide are rapidly inactivated by the enzyme DPP-4. DPP-4 inhibitor agents act by blocking the active site of DPP-4, thereby preventing inactivation of and prolonging the duration of action of incretins, which in turn helps to correct the defective insulin and glucagon secretion that marks type 2 diabetes. Clinical studies to date indicate that DPP-4 inhibitors effectively stimulate insulin secretion, suppress glucagon release, and improve glucose control in patients with type 2 diabetes. These agents are well tolerated and have a low incidence of adverse effects. Conclusions: The DPP-4 inhibitors are novel agents for the treatment of type 2 diabetes. Compounds under development in this new class of oral antidiabetic drugs may be free of the limitations of current therapies.
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Affiliation(s)
- R Keith Campbell
- College of Pharmacy, Wegner Hall #147, PO Box 646510, Washington State University, Pullman, WA 99164, USA.
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11
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Franz MJ. Themed Review: Lifestyle Interventions Across the Continuum of Type 2 Diabetes: Reducing the Risks of Diabetes. Am J Lifestyle Med 2016. [DOI: 10.1177/1559827607304296] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Type 2 diabetes is a progressive disease that results from defects in insulin action (insulin resistance), insulin secretion (insulin deficiency), or both. The progressive decline in β-c ell function requires that medical therapy progress from lifestyle interventions for prevention of diabetes to medical nutrition therapy (MNT) alone for diabetes management to MNT in combination with glucose-lowering medications that target the multiple pathophysiologic aspects of diabetes to MNT with insulin. MNT also progresses from prevention of obesity or weight gain to improving insulin resistance to contributing to improved metabolic control of glucose, lipids, and blood pressure; however, MNT is important throughout the continuum of diabetes and its medical management. Early diagnosis and aggressive therapy decrease the risk of diabetes-related complications.
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Levine JA, Kaihara KA, Layden BT, Wicksteed B. Long-term activation of PKA in β-cells provides sustained improvement to glucose control, insulin sensitivity and body weight. Islets 2016; 8:125-34. [PMID: 27340937 PMCID: PMC5029204 DOI: 10.1080/19382014.2016.1198457] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Type 2 diabetes is associated with obesity, insulin resistance and β-cell failure. Therapeutic aims are to reduce adiposity, improve insulin sensitivity and enhance β-cell function. However, it has been proposed that chronically increasing insulin release leads to β-cell exhaustion and failure. We previously developed mice to have increased activity of the cAMP-dependent protein kinase (PKA), specifically in β-cells (β-caPKA mice). β-caPKA mice have enhanced acute phase insulin release, which is the primary determinant of the efficacy of glucose clearance. Here these mice were used to determine the sustainability of enhanced insulin secretion, and to characterize peripheral effects of enhanced β-cell function. Increased PKA activity was induced by tamoxifen administration at 10 weeks of age. Male mice were aged to 12 months of age and female mice to 16 months. Glucose control in both male and female β-caPKA mice was significantly improved relative to littermate controls with ad libitum feeding, upon refeeding after fasting, and in glucose tolerance tests. In female mice insulin release was both greater and more rapid than in controls. Female mice were more insulin sensitive than controls. Male and female β-caPKA mice had lower body weights than controls. DEXA analysis of male mice revealed that this was due to reduced adiposity and not due to changes in lean body mass. This study indicates that targeting β-cells to enhance insulin release is sustainable, maintains insulin sensitivity and reduces body weight. These data identify β-cell PKA activity as a novel target for obesity therapies.
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Affiliation(s)
- Joshua A. Levine
- Division of Endocrinology, Metabolism and Molecular Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Kelly A. Kaihara
- Committee for Molecular Metabolism and Nutrition, The University of Chicago, Chicago, IL, USA
- Bio-Rad Laboratories, Hercules, CA, USA
| | - Brian T. Layden
- Division of Endocrinology, Metabolism and Molecular Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
- Jesse Brown Veterans Affairs Medical Center, Chicago, IL, USA
| | - Barton Wicksteed
- Division of Endocrinology, Metabolism and Molecular Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
- Committee for Molecular Metabolism and Nutrition, The University of Chicago, Chicago, IL, USA
- CONTACT Barton Wicksteed Division of Endocrinology, Metabolism and Molecular Medicine, Tarry Building 15-735 300 East Superior St., Chicago, IL 60611-3008, USA
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13
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Liu R, Wong W, IJzerman AP. Human G protein-coupled receptor studies in Saccharomyces cerevisiae. Biochem Pharmacol 2016; 114:103-15. [DOI: 10.1016/j.bcp.2016.02.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 02/12/2016] [Indexed: 12/22/2022]
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14
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Lim GE, Piske M, Lulo JE, Ramshaw HS, Lopez AF, Johnson JD. Ywhaz/14-3-3ζ Deletion Improves Glucose Tolerance Through a GLP-1-Dependent Mechanism. Endocrinology 2016; 157:2649-59. [PMID: 27167773 DOI: 10.1210/en.2016-1016] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Multiple signaling pathways mediate the actions of metabolic hormones to control glucose homeostasis, but the proteins that coordinate such networks are poorly understood. We previously identified the molecular scaffold protein, 14-3-3ζ, as a critical regulator of in vitro β-cell survival and adipogenesis, but its metabolic roles in glucose homeostasis have not been studied in depth. Herein, we report that Ywhaz gene knockout mice (14-3-3ζKO) exhibited elevated fasting insulin levels while maintaining normal β-cell responsiveness to glucose when compared with wild-type littermate controls. In contrast with our observations after an ip glucose bolus, glucose tolerance was significantly improved in 14-3-3ζKO mice after an oral glucose gavage. This improvement in glucose tolerance was associated with significantly elevated fasting glucagon-like peptide-1 (GLP-1) levels. 14-3-3ζ knockdown in GLUTag L cells elevated GLP-1 synthesis and increased GLP-1 release. Systemic inhibition of the GLP-1 receptor attenuated the improvement in oral glucose tolerance that was seen in 14-3-3ζKO mice. When taken together these findings demonstrate novel roles of 14-3-3ζ in the regulation of glucose homeostasis and suggest that modulating 14-3-3ζ levels in intestinal L cells may have beneficial metabolic effects through GLP-1-dependent mechanisms.
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Affiliation(s)
- Gareth E Lim
- Department of Cellular and Physiological Sciences (G.E.L., M.P., J.D.J.), University of British Columbia, Vancouver, BC, Canada; ALPCO (J.E.L.), Salem, New Hampshire; and The Centre for Cancer Biology (H.S.R., A.F.L.), South Australia Pathology and University of South Australia, Adelaide, Australia
| | - Micah Piske
- Department of Cellular and Physiological Sciences (G.E.L., M.P., J.D.J.), University of British Columbia, Vancouver, BC, Canada; ALPCO (J.E.L.), Salem, New Hampshire; and The Centre for Cancer Biology (H.S.R., A.F.L.), South Australia Pathology and University of South Australia, Adelaide, Australia
| | - James E Lulo
- Department of Cellular and Physiological Sciences (G.E.L., M.P., J.D.J.), University of British Columbia, Vancouver, BC, Canada; ALPCO (J.E.L.), Salem, New Hampshire; and The Centre for Cancer Biology (H.S.R., A.F.L.), South Australia Pathology and University of South Australia, Adelaide, Australia
| | - Hayley S Ramshaw
- Department of Cellular and Physiological Sciences (G.E.L., M.P., J.D.J.), University of British Columbia, Vancouver, BC, Canada; ALPCO (J.E.L.), Salem, New Hampshire; and The Centre for Cancer Biology (H.S.R., A.F.L.), South Australia Pathology and University of South Australia, Adelaide, Australia
| | - Angel F Lopez
- Department of Cellular and Physiological Sciences (G.E.L., M.P., J.D.J.), University of British Columbia, Vancouver, BC, Canada; ALPCO (J.E.L.), Salem, New Hampshire; and The Centre for Cancer Biology (H.S.R., A.F.L.), South Australia Pathology and University of South Australia, Adelaide, Australia
| | - James D Johnson
- Department of Cellular and Physiological Sciences (G.E.L., M.P., J.D.J.), University of British Columbia, Vancouver, BC, Canada; ALPCO (J.E.L.), Salem, New Hampshire; and The Centre for Cancer Biology (H.S.R., A.F.L.), South Australia Pathology and University of South Australia, Adelaide, Australia
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15
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Samson SL, Garber AJ. Prevention of type 2 Diabetes Mellitus: Potential of pharmacological agents. Best Pract Res Clin Endocrinol Metab 2016; 30:357-71. [PMID: 27432071 DOI: 10.1016/j.beem.2016.06.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
People with impaired glucose tolerance or impaired fasting glucose, or "pre-diabetes", are at high risk for progression to type 2 diabetes, as are those with metabolic syndrome or a history of gestational diabetes. Both glucose-lowering and anti-obesity pharmacotherapies have been studied to determine if the onset of type 2 diabetes can be delayed or prevented. Here we review the available data in the field. The most common theme is the reduction in insulin resistance, such as with weight loss, decreasing demands on the beta cell to improve insulin secretion and prolong its function. Overall, therapies which decrease diabetes incidence in high-risk populations delay the onset of diabetes but do not correct the underlying beta cell defect.
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Affiliation(s)
- Susan L Samson
- Department of Medicine, Baylor College of Medicine, One Baylor Plaza, ABBR R615, Houston, TX 77030, USA.
| | - Alan J Garber
- Department of Medicine, Baylor College of Medicine, One Baylor Plaza- BCM 620, Houston, TX 77030, USA; Department of Molecular and Cellular Biology, Baylor College of Medicine, One Baylor Plaza- BCM 620, Houston, TX 77030, USA; Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza- BCM 620, Houston, TX 77030, USA
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16
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Schernthaner-Reiter MH, Schernthaner G. Combination therapy of SGLT2 inhibitors with incretin-based therapies for the treatment of type 2 diabetes mellitus: Effects and mechanisms of action. Expert Rev Endocrinol Metab 2016; 11:281-296. [PMID: 30058933 DOI: 10.1586/17446651.2016.1151783] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Type 2 diabetes mellitus (T2DM) is a growing health problem worldwide; its pathogenesis is multifactorial and its progressive nature often necessitates a combination therapy with multiple antihyperglycemic agents. Sodium glucose cotransporter 2 (SGLT2) inhibitors and the incretin-based therapies - dipeptidyl peptidase 4(DPP-4) inhibitors and glucagon-like peptide 1 (GLP-1) receptor agonists - were introduced for the treatment of T2DM within the last decade. Evidence of the beneficial effects of these antihyperglycemic agents on micro- and macrovascular complications have started to emerge, which will become important in individualizing different combinations of antihyperglycemic agents to different patient populations. We review here the mechanisms of action, glycemic and cardiovascular effects of SGLT2 inhibitors and incretin-based therapies and their combination in the treatment of T2DM.
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Affiliation(s)
- Marie Helene Schernthaner-Reiter
- a Clinical Division of Endocrinology and Metabolism, Department of Internal Medicine III , Medical University of Vienna , Vienna , Austria
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D'Alessio D. Is GLP-1 a hormone: Whether and When? J Diabetes Investig 2016; 7 Suppl 1:50-5. [PMID: 27186356 PMCID: PMC4854505 DOI: 10.1111/jdi.12466] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Accepted: 12/21/2015] [Indexed: 01/24/2023] Open
Abstract
Glucagon‐like peptide‐1 (GLP‐1) is a product of proglucagon cleavage synthesized in L cells in the intestinal mucosa, α‐cells in the pancreatic islet, and neurons in the nucleus of the solitary tract. GLP‐1 is essential for normal glucose tolerance and acts through a specific GLP‐1 receptor that is expressed by islet β‐cells as well as other cell types. Because plasma concentrations of GLP‐1 increase following meal ingestion it has been generally presumed that GLP‐1 acts as a hormone, communicating information from the intestine to the endocrine pancreas through the circulation. However, there are a number of problems with this model including low circulating concentrations of GLP‐1 in plasma, limited changes after meal ingestion and rapid metabolism in the plasma. Moreover, antagonism of systemic GLP‐1 action impairs insulin secretion in the fasting state, suggesting that the GLP‐1r is active even when plasma GLP‐1 levels are low and unchanging. Consistent with these observations, deletion of the GLP‐1r from islet β‐cells causes intolerance after IP or IV glucose, challenges that do not induce GLP‐1 secretion. Taken together, these data support a model whereby GLP‐1 acts through neural or paracrine mechanisms to regulate physiologic insulin secretion. In contrast, bariatric surgery seems to be a condition in which circulating GLP‐1 could have an endocrine effect. Both gastric bypass and sleeve gastrectomy are associated with substantial increases in postprandial GLP‐1 release and in these conditions interference with GLP‐1r signaling has a significant impact on glucose regulation after eating. Thus, with either bariatric surgery or treatment with long‐acting GLP‐1r agonists, circulating peptide mediates insulinotropic activity. Overall, a case can be made that physiologic actions of GLP‐1 are not hormonal, but that an endocrine mechanism of GLP‐1r activation can be co‐opted for therapeutics.
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Affiliation(s)
- David D'Alessio
- Division of Endocrinology, Metabolism and Nutrition Duke University Medical Center Durham North Carolina USA
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Naik H, Czerniak R, Vakilynejad M. Application of pharmacometric approaches to evaluate effect of weight and renal function on pharmacokinetics of alogliptin. Br J Clin Pharmacol 2016; 81:700-12. [PMID: 26617339 DOI: 10.1111/bcp.12853] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Revised: 11/13/2015] [Accepted: 11/26/2015] [Indexed: 02/04/2023] Open
Abstract
AIMS The aims of the study were to characterize the pharmacokinetics (PK) of alogliptin in healthy and type 2 diabetes mellitus (T2DM) subjects using a population PK approach and to assess the influence of various covariates on alogliptin exposure. METHODS Plasma concentration data collected from two phase 1 studies and one phase 3 study following administration of alogliptin (12.5-400 mg) were used for the PK model development. One- and two-compartment models were evaluated as base structural PK models. The impact of selected covariates was assessed using stepwise forward selection and backward elimination procedures. The predictability and robustness of the final model was evaluated using visual predictive check and bootstrap analyses. The final model was used to perform simulations and guide appropriate dose adjustments. RESULTS A two-compartment model with first-order absorption and elimination best described the alogliptin concentration vs. time profiles. Creatinine clearance and weight had a statistically significant effect on the oral clearance (CL/F) of alogliptin. The model predicted a lower CL/F (17%, 35%, 80%) and a higher systemic exposure (56%, 89%, 339%) for subjects with mild, moderate and severe renal impairment, respectively, compared with healthy subjects. Effect of weight on CL/F was not considered clinically relevant. Simulations at different doses of alogliptin support the approved doses of 12.5 mg and 6.25 mg for patients with moderate and severe renal impairment, respectively. CONCLUSIONS The PK of alogliptin was well characterized by the model. The analysis suggested an alogliptin dose adjustment for subjects with moderate-to-severe renal impairment and no dose adjustments based on weight.
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Affiliation(s)
- Himanshu Naik
- Takeda Global Research & Development Center, Inc, One Takeda Parkway, Deerfield, IL, 60015, USA
| | - Richard Czerniak
- Takeda Global Research & Development Center, Inc, One Takeda Parkway, Deerfield, IL, 60015, USA
| | - Majid Vakilynejad
- Takeda Global Research & Development Center, Inc, One Takeda Parkway, Deerfield, IL, 60015, USA
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19
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Guo XH. The value of short- and long-acting glucagon-like peptide-1 agonists in the management of type 2 diabetes mellitus: experience with exenatide. Curr Med Res Opin 2016; 32:61-76. [PMID: 26439329 DOI: 10.1185/03007995.2015.1103214] [Citation(s) in RCA: 20] [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] [Indexed: 11/23/2022]
Abstract
BACKGROUND Only about half of patients with type 2 diabetes treated with antihyperglycemic drugs achieve glycemic control (HbA1c <7%), most commonly due to poor treatment adherence. Glucagon-like peptide-1 (GLP-1) receptor agonists act on multiple targets involved in glucose homeostasis and have a low risk of causing hypoglycemia. While GLP-1 receptor (GLP-1R) agonists share the same mechanism of action, clinical profiles of individual agents differ, particularly between short- and long-acting agents. In this article, recent findings regarding the pharmacology of GLP-1 agonists are reviewed, and the clinical effects of short- versus long-acting agents are compared. DATA SOURCES Relevant articles were identified through a search of PubMed using the keywords glucagon-like peptide-1, GLP-1, glucagon-like peptide-1 receptor agonist, GLP-1R agonist, and exenatide for publications up to 22 May 2015. Supporting data were obtained from additional searches for albiglutide, dulaglutide, liraglutide and lixisenatide as well as from the bibliographies of key articles. FINDINGS Short-acting GLP-1R agonists produce greater reductions in postprandial glucose levels by slowing gastric emptying, whereas long-acting GLP-1R agonists produce greater reductions in fasting blood glucose by stimulating insulin secretion from the pancreas. These characteristics can be exploited to provide individualized treatment to patients. A large body of evidence supports the benefits of short- and long-acting exenatide as add-on therapy in patients with inadequate glycemic control despite maximum tolerated doses of metformin and/or sulfonylurea. Exenatide is generally well tolerated and no new safety concerns were identified during long-term follow-up of up to 5 years. A limitation of this review of short-and long-acting GLP-1 receptor agonists is that it focuses on exenatide rather than all the drugs in this class. However, the focus on a single molecule helps to avoid any confusion that may be introduced as a result of differences in molecular structure and size. CONCLUSIONS Short-acting GLP-1R agonists including exenatide are well suited to patients with type 2 diabetes with exaggerated postprandial glucose excursions and for co-administration with basal insulin therapy. Long-acting GLP-1R agonists including once weekly exenatide offer greater convenience and are well suited to patients who require specific control of fasting hyperglycemia.
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Affiliation(s)
- Xiao-Hui Guo
- a Endocrinology Department , Peking University First Hospital , Beijing , China
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20
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Morettini M, Di Nardo F, Cogo CE, Faelli E, Fioretti S, Burattini L, Ruggeri P. Estimation of second-phase insulin secretion in the Zucker fatty rat. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2016; 2016:3494-3497. [PMID: 28324988 DOI: 10.1109/embc.2016.7591481] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The purpose of the present study was to test the efficacy of the empiric index SPIR (Second-phase Insulin Release) in the quantification of second-phase insulin secretion in the Zucker Fatty Rat. SPIR index is defined as the area under the curve of insulin between 8 and 90 min after an Intravenous Glucose Tolerance Test (IVGTT). The validation of such index was performed against the second-phase β-cell responsiveness index (Φ2) provided by C-peptide minimal model. To this aim, Φ2 and SPIR were simultaneously computed from IVGTT data, measured in six Zucker fatty rats (ZFR), 7-to-9week-old, and seven age-matched Zucker lean rats (ZLR). SPIR index showed a significant linear correlation with Φ2 (Pearson's correlation coefficient, r = 0.91, R-square = 0.82, P<;0.001). Moreover, both Φ2 (P<;0.001) and SPIR (P<;0.001) showed a significant increase, in the ZFRs, compared to control group (ZLR). These findings suggest that the SPIR index is able to provide similar information of Φ2, in the evaluation of the second-phase insulin secretion and of its alteration in Zucker Fatty Rats. Thus, the study proposes the SPIR, as a suitable index for a simple, reliable and low-cost quantification of the second-phase insulin secretion in ZFR.
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21
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Bosley JR, Maurer TS, Musante CJ. Systems Pharmacology Modeling in Type 2 Diabetes Mellitus. SYSTEMS PHARMACOLOGY AND PHARMACODYNAMICS 2016. [DOI: 10.1007/978-3-319-44534-2_20] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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22
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Sandoval DA, D'Alessio DA. Physiology of proglucagon peptides: role of glucagon and GLP-1 in health and disease. Physiol Rev 2015; 95:513-48. [PMID: 25834231 DOI: 10.1152/physrev.00013.2014] [Citation(s) in RCA: 307] [Impact Index Per Article: 34.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The preproglucagon gene (Gcg) is expressed by specific enteroendocrine cells (L-cells) of the intestinal mucosa, pancreatic islet α-cells, and a discrete set of neurons within the nucleus of the solitary tract. Gcg encodes multiple peptides including glucagon, glucagon-like peptide-1, glucagon-like peptide-2, oxyntomodulin, and glicentin. Of these, glucagon and GLP-1 have received the most attention because of important roles in glucose metabolism, involvement in diabetes and other disorders, and application to therapeutics. The generally accepted model is that GLP-1 improves glucose homeostasis indirectly via stimulation of nutrient-induced insulin release and by reducing glucagon secretion. Yet the body of literature surrounding GLP-1 physiology reveals an incompletely understood and complex system that includes peripheral and central GLP-1 actions to regulate energy and glucose homeostasis. On the other hand, glucagon is established principally as a counterregulatory hormone, increasing in response to physiological challenges that threaten adequate blood glucose levels and driving glucose production to restore euglycemia. However, there also exists a potential role for glucagon in regulating energy expenditure that has recently been suggested in pharmacological studies. It is also becoming apparent that there is cross-talk between the proglucagon derived-peptides, e.g., GLP-1 inhibits glucagon secretion, and some additive or synergistic pharmacological interaction between GLP-1 and glucagon, e.g., dual glucagon/GLP-1 agonists cause more weight loss than single agonists. In this review, we discuss the physiological functions of both glucagon and GLP-1 by comparing and contrasting how these peptides function, variably in concert and opposition, to regulate glucose and energy homeostasis.
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Affiliation(s)
- Darleen A Sandoval
- Division of Endocrinology and Metabolism, University of Cincinnati College of Medicine, Cincinnati, Ohio
| | - David A D'Alessio
- Division of Endocrinology and Metabolism, University of Cincinnati College of Medicine, Cincinnati, Ohio
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Hasson BR, Apovian C, Istfan N. Racial/Ethnic Differences in Insulin Resistance and Beta Cell Function: Relationship to Racial Disparities in Type 2 Diabetes among African Americans versus Caucasians. Curr Obes Rep 2015; 4:241-9. [PMID: 26627219 DOI: 10.1007/s13679-015-0150-2] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Both biological and sociocultural factors have been implicated in the well-documented racial disparity in incidence and prevalence of type 2 diabetes (T2D) between African Americans (AA) and non-Hispanic whites (NHW). This review examines the extent to which biological differences in glucose metabolism, specifically insulin resistance and beta cell function (BCF), contribute to this disparity. The majority of available data suggests that AA are more insulin resistant and have upregulated BCF compared to NHW. Increasing evidence implicates high insulin secretion as a cause rather than consequence of T2D; therefore, upregulated BCF in AA may specifically confer increased risk of T2D in this cohort. Racial disparities in the metabolic characteristics of T2D have direct implications for the treatment and health consequences of this disease; therefore, future research is needed to determine whether strategies to reduce insulin secretion in AA may prevent or delay T2D and lessen racial health disparities.
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Affiliation(s)
- Brooke R Hasson
- Division of Endocrinology, Diabetes, and Nutrition, Boston University School of Medicine, 88 East Newton Street, Boston, MA, 02118, USA.
| | - Caroline Apovian
- Division of Endocrinology, Diabetes, and Nutrition, Boston University School of Medicine, 88 East Newton Street, Boston, MA, 02118, USA.
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24
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Blevins T. Control of Postprandial Glucose Levels with Insulin in Type 2 Diabetes. Postgrad Med 2015; 123:135-47. [DOI: 10.3810/pgm.2011.07.2313] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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Weston C, Poyner D, Patel V, Dowell S, Ladds G. Investigating G protein signalling bias at the glucagon-like peptide-1 receptor in yeast. Br J Pharmacol 2014; 171:3651-65. [PMID: 24712679 PMCID: PMC4128063 DOI: 10.1111/bph.12716] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Revised: 03/20/2014] [Accepted: 03/29/2014] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND AND PURPOSE The glucagon-like peptide 1 (GLP-1) receptor performs an important role in glycaemic control, stimulating the release of insulin. It is an attractive target for treating type 2 diabetes. Recently, several reports of adverse side effects following prolonged use of GLP-1 receptor therapies have emerged: most likely due to an incomplete understanding of signalling complexities. EXPERIMENTAL APPROACH We describe the expression of the GLP-1 receptor in a panel of modified yeast strains that couple receptor activation to cell growth via single Gα/yeast chimeras. This assay enables the study of individual ligand-receptor G protein coupling preferences and the quantification of the effect of GLP-1 receptor ligands on G protein selectivity. KEY RESULTS The GLP-1 receptor functionally coupled to the chimeras representing the human Gαs, Gαi and Gαq subunits. Calculation of the dissociation constant for a receptor antagonist, exendin-3 revealed no significant difference between the two systems. We obtained previously unobserved differences in G protein signalling bias for clinically relevant therapeutic agents, liraglutide and exenatide; the latter displaying significant bias for the Gαi pathway. We extended the use of the system to investigate small-molecule allosteric compounds and the closely related glucagon receptor. CONCLUSIONS AND IMPLICATIONS These results provide a better understanding of the molecular events involved in GLP-1 receptor pleiotropic signalling and establish the yeast platform as a robust tool to screen for more selective, efficacious compounds acting at this important class of receptors in the future.
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Affiliation(s)
- C Weston
- Division of Biomedical Cell Biology, Warwick Medical School, University of Warwick, Coventry, UK
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Lindgren J, Refai E, Zaitsev SV, Abrahmsén L, Berggren PO, Karlström AE. A GLP-1 receptor agonist conjugated to an albumin-binding domain for extended half-life. Biopolymers 2014; 102:252-9. [DOI: 10.1002/bip.22474] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Revised: 02/05/2014] [Accepted: 02/13/2014] [Indexed: 12/25/2022]
Affiliation(s)
- Joel Lindgren
- Division of Protein Technology, School of Biotechnology; KTH Royal Institute of Technology, AlbaNova University Center; SE 106 91 Stockholm Sweden
| | - Essam Refai
- Karolinska Institutet, The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska University Hospital L1; 171 76 Stockholm Sweden
| | - Sergei V. Zaitsev
- Karolinska Institutet, The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska University Hospital L1; 171 76 Stockholm Sweden
- Lomonosov Moscow State University, Belozersky Institute of Physico-Chemical Biology; 119991 Moscow Russia
| | | | - Per-Olof Berggren
- Karolinska Institutet, The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska University Hospital L1; 171 76 Stockholm Sweden
| | - Amelie Eriksson Karlström
- Division of Protein Technology, School of Biotechnology; KTH Royal Institute of Technology, AlbaNova University Center; SE 106 91 Stockholm Sweden
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27
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Torekov SS, Holst JJ, Ehlers MR. Dose response of continuous subcutaneous infusion of recombinant glucagon-like peptide-1 in combination with metformin and sulphonylurea over 12 weeks in patients with type 2 diabetes mellitus. Diabetes Obes Metab 2014; 16:451-6. [PMID: 24251641 DOI: 10.1111/dom.12240] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Revised: 10/15/2013] [Accepted: 11/12/2013] [Indexed: 11/28/2022]
Abstract
AIMS Any differences observed between natural glucagon-like peptide-1 (GLP-1) and studies obtained with analogues might call for renewed considerations concerning the use and design of such analogues. Thus, we aimed to evaluate the dose-response relationship of recombinant glucagon-like peptide-1 (7-36) amide (rGLP-1) administered by continuous subcutaneous infusion (CSCI) in subjects with type 2 diabetes. METHODS We compared the efficacy and safety of three doses of recombinant GLP-1, ranging from 1.25 to 5.0 pmol/kg/min (pkm) and placebo, given by continuous subcutaneous infusion over 3 months in combination with metformin and sulphonylurea (SU), to lower haemoglobin A1c (HbA1c), fasting plasma glucose and weight in 95 type 2 diabetes patients with inadequate glycaemic control. RESULTS The mean decreases in HbA1c at endpoint (week 12) were significantly greater for all three rGLP-1 dose groups when each was compared with the placebo group, with the greatest decrease occurring in the 5.0 pkm dose group (-1.3%, s.d. ± 0.18, p < 0.001). The mean decreases in fasting plasma glucose from baseline to endpoint were significantly greater for all three rGLP-1 dose groups than for the placebo group, with the greatest decrease occurring in the 5.0 pkm dose group (-26.0 mg/dl, s.d. ± 8.5, p = 0.02). Body weight was significantly reduced by 1.8 kg (s.d. ± 1.3) in the 1.25 pkm dose group only (p = 0.04). CONCLUSIONS Administration of rGLP-1 by CSCI over a 12-week period in combination with metformin and an SU had a dose dependent effect in lowering HbA1c and fasting plasma glucose. However, administration of rGLP-1 by CSCI may be less effective with respect to lowering of body weight compared with the daily and once weekly analogues.
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Affiliation(s)
- S S Torekov
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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Gastaldelli A, Brodows RG, D'Alessio D. The effect of chronic twice daily exenatide treatment on β-cell function in new onset type 2 diabetes. Clin Endocrinol (Oxf) 2014; 80:545-53. [PMID: 23574529 DOI: 10.1111/cen.12199] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Revised: 12/06/2012] [Accepted: 03/07/2013] [Indexed: 01/23/2023]
Abstract
OBJECTIVE To determine the effect of chronic daily exenatide treatment on β-cell function in type 2 diabetes (T2DM). BACKGROUND Glucagon-like peptide receptor agonists, such as exenatide, are commonly used to treat patients with T2DM. Drugs in this class are insulinotropic but lower blood glucose by multiple mechanisms such that effects on β-cell function can be difficult to discern by conventional measures. DESIGN Seventy-nine subjects with previously untreated T2DM were studied before and after 24 weeks of treatment with one of the two doses of exenatide, 5- or 10-μg twice daily, or placebo. All subjects had oral glucose tolerance tests (OGTT) before and after randomization with measurement of plasma glucose, insulin and C-peptide concentrations. Insulin secretion rates (ISR), peripheral insulin sensitivity (OGIS) and hepatic insulin resistance index (Hep-IR) were calculated. RESULTS During the trial, all three groups lost similar, small but significant, amounts of weight. Compared to placebo, 24 weeks of daily high- or low-dose exenatide treatment reduced HbA1c and improved fasting and postprandial hyperglycaemia. Exenatide was associated with improved OGIS and Hep-IR independent of changes in weight. Plasma insulin levels and ISR during the OGTT did not differ before or after treatment with exenatide or placebo. However, when considered as a function of plasma glucose and insulin sensitivity, both doses of exenatide improved ISR proportionately to the improvement in plasma glucose. The higher dose of exenatide was associated with a significant improvement in β-cell sensitivity to glucose. CONCLUSIONS These findings demonstrate that in persons with early T2DM, chronic treatment with exenatide enhanced ISR and increased β-cell sensitivity to glucose. These improvements in β-cell function were not clearly reflected in plasma insulin and C-peptide levels, but became apparent when glycemia and insulin sensitivity were accounted for.
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Affiliation(s)
- Amalia Gastaldelli
- Institute of Clinical Physiology, National Research Council, Pisa, Italy
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Abstract
Glucose metabolism is normally regulated by a feedback loop including islet β cells and insulin-sensitive tissues, in which tissue sensitivity to insulin affects magnitude of β-cell response. If insulin resistance is present, β cells maintain normal glucose tolerance by increasing insulin output. Only when β cells cannot release sufficient insulin in the presence of insulin resistance do glucose concentrations rise. Although β-cell dysfunction has a clear genetic component, environmental changes play an essential part. Modern research approaches have helped to establish the important role that hexoses, aminoacids, and fatty acids have in insulin resistance and β-cell dysfunction, and the potential role of changes in the microbiome. Several new approaches for treatment have been developed, but more effective therapies to slow progressive loss of β-cell function are needed. Recent findings from clinical trials provide important information about methods to prevent and treat type 2 diabetes and some of the adverse effects of these interventions. However, additional long-term studies of drugs and bariatric surgery are needed to identify new ways to prevent and treat type 2 diabetes and thereby reduce the harmful effects of this disease.
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Affiliation(s)
- Steven E Kahn
- Division of Metabolism, Endocrinology and Nutrition, Department of Medicine, VA Puget Sound Health Care System, University of Washington, Seattle, WA, USA.
| | - Mark E Cooper
- Diabetes Division, Baker IDI Heart and Diabetes Institute, Melbourne, VIC, Australia
| | - Stefano Del Prato
- Department of Clinical and Experimental Medicine, University of Pisa School of Medicine, Pisa, Italy
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30
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Affiliation(s)
- Jenny Tong
- Division of Endocrinology, Diabetes and Metabolism, University of Cincinnati, Cincinnati, OH
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Werner U. Effects of the GLP-1 receptor agonist lixisenatide on postprandial glucose and gastric emptying--preclinical evidence. J Diabetes Complications 2014; 28:110-4. [PMID: 23992745 DOI: 10.1016/j.jdiacomp.2013.06.003] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2013] [Revised: 05/30/2013] [Accepted: 06/11/2013] [Indexed: 11/15/2022]
Abstract
In addition to promoting glucose homeostasis, glucagon-like peptide 1 (GLP-1) has a number of extra-pancreatic effects that regulate appetite and body weight. GLP-1 delays gastric emptying, which is vital for postprandial glucose (PPG) control. As GLP-1 is rapidly degraded by protease dipeptidyl peptidase-4, a number of degradation-resistant GLP-1 receptor agonists (GLP-1RAs) have been developed for the treatment of Type 2 diabetes mellitus. These agents can be broadly categorized as being short- or long-acting, based on their pharmacokinetic profile. Short-acting agonists predominantly affect PPG and delay gastric emptying in a sustained manner, whereas long-acting agents largely affect fasting plasma glucose and their delay in gastric emptying appears to be subjected to tachyphylaxis. Lixisenatide is a "short-acting" once-daily prandial GLP-1RA. This review provides an overview of the preclinical studies that are currently available and that evaluate the efficacy of lixisenatide on gastric emptying and PPG levels. The preclinical evidence outlined in this review supports the efficacy of lixisenatide in reducing PPG excursions and delaying gastric emptying. Furthermore, in contrast to long-acting agents, the actions of lixisenatide do not appear to be subjected to tachyphylaxis.
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Affiliation(s)
- Ulrich Werner
- Sanofi-Aventis Deutschland GmbH, Frankfurt am Main, Germany.
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Cersosimo E, Solis-Herrera C, Trautmann ME, Malloy J, Triplitt CL. Assessment of pancreatic β-cell function: review of methods and clinical applications. Curr Diabetes Rev 2014; 10:2-42. [PMID: 24524730 PMCID: PMC3982570 DOI: 10.2174/1573399810666140214093600] [Citation(s) in RCA: 168] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Revised: 12/02/2013] [Accepted: 12/03/2013] [Indexed: 12/19/2022]
Abstract
Type 2 diabetes mellitus (T2DM) is characterized by a progressive failure of pancreatic β-cell function (BCF) with insulin resistance. Once insulin over-secretion can no longer compensate for the degree of insulin resistance, hyperglycemia becomes clinically significant and deterioration of residual β-cell reserve accelerates. This pathophysiology has important therapeutic implications. Ideally, therapy should address the underlying pathology and should be started early along the spectrum of decreasing glucose tolerance in order to prevent or slow β-cell failure and reverse insulin resistance. The development of an optimal treatment strategy for each patient requires accurate diagnostic tools for evaluating the underlying state of glucose tolerance. This review focuses on the most widely used methods for measuring BCF within the context of insulin resistance and includes examples of their use in prediabetes and T2DM, with an emphasis on the most recent therapeutic options (dipeptidyl peptidase-4 inhibitors and glucagon-like peptide-1 receptor agonists). Methods of BCF measurement include the homeostasis model assessment (HOMA); oral glucose tolerance tests, intravenous glucose tolerance tests (IVGTT), and meal tolerance tests; and the hyperglycemic clamp procedure. To provide a meaningful evaluation of BCF, it is necessary to interpret all observations within the context of insulin resistance. Therefore, this review also discusses methods utilized to quantitate insulin-dependent glucose metabolism, such as the IVGTT and the euglycemic-hyperinsulinemic clamp procedures. In addition, an example is presented of a mathematical modeling approach that can use data from BCF measurements to develop a better understanding of BCF behavior and the overall status of glucose tolerance.
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Affiliation(s)
| | | | | | | | - Curtis L Triplitt
- Texas Diabetes Institute, University of Texas Health Science Center-San Antonio, 701 S. Zarzamora, MS 10-5, San Antonio, TX 78207, USA.
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Cernea S, Dobreanu M. Diabetes and beta cell function: from mechanisms to evaluation and clinical implications. Biochem Med (Zagreb) 2013; 23:266-80. [PMID: 24266296 PMCID: PMC3900074 DOI: 10.11613/bm.2013.033] [Citation(s) in RCA: 125] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Diabetes is a complex, heterogeneous condition that has beta cell dysfunction at its core. Many factors (e.g. hyperglycemia/glucotoxicity, lipotoxicity, autoimmunity, inflammation, adipokines, islet amyloid, incretins and insulin resistance) influence the function of pancreatic beta cells. Chronic hyperglycaemia may result in detrimental effects on insulin synthesis/secretion, cell survival and insulin sensitivity through multiple mechanisms: gradual loss of insulin gene expression and other beta-cell specific genes; chronic endoplasmic reticulum stress and oxidative stress; changes in mitochondrial number, morphology and function; disruption in calcium homeostasis. In the presence of hyperglycaemia, prolonged exposure to increased free fatty acids result in accumulation of toxic metabolites in the cells (“lipotoxicity”), finally causing decreased insulin gene expression and impairment of insulin secretion. The rest of the factors/mechanisms which impact on the course of the disease are also discusses in detail. The correct assessment of beta cell function requires a concomitant quantification of insulin secretion and insulin sensitivity, because the two variables are closely interrelated. In order to better understand the fundamental pathogenetic mechanisms that contribute to disease development in a certain individual with diabetes, additional markers could be used, apart from those that evaluate beta cell function. The aim of the paper was to overview the relevant mechanisms/factors that influence beta cell function and to discuss the available methods of its assessment. In addition, clinical considerations are made regarding the therapeutical options that have potential protective effects on beta cell function/mass by targeting various underlying factors and mechanisms with a role in disease progression.
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Affiliation(s)
- Simona Cernea
- Diabetes, Nutrition and Metabolic Diseases Outpatient Unit, Emergency County Clinical Hospital, Târgu Mureş, Romania.
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Forst T, Pfützner A. Pharmacological profile, efficacy and safety of lixisenatide in type 2 diabetes mellitus. Expert Opin Pharmacother 2013; 14:2281-96. [DOI: 10.1517/14656566.2013.838559] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Samson SL, Bajaj M. Potential of incretin-based therapies for non-alcoholic fatty liver disease. J Diabetes Complications 2013; 27:401-6. [PMID: 23352496 DOI: 10.1016/j.jdiacomp.2012.12.005] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2012] [Revised: 12/05/2012] [Accepted: 12/17/2012] [Indexed: 12/16/2022]
Abstract
Non-alcoholic fatty liver disease (NAFLD) is becoming an epidemic, paralleling the increased prevalence of obesity and diabetes, which are risk factors. In this review, we present the current pre-clinical evidence showing that GLP-1 analogues and DPP4 inhibitors can improve hepatic steatosis. Although some of the effects could be due to overall improvement in metabolic parameters, there are data to support improvements independent of weight loss, as well as direct effects on the hepatocyte in vitro. Multiple hepatocyte signal transduction pathways appear to be activated by GLP-1 and its analogues, with both AMP-activated protein kinase and Akt proposed to be key players in improving hepatic steatosis. However, it is controversial as to whether the pancreatic-type GLP-1 receptor is present or responsible for conferring the GLP-1 signal in the hepatocyte. In total, the data support the need for more rigorous prospective clinical trials to further investigate the potential of incretin therapies for treatment of NAFLD.
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Affiliation(s)
- Susan L Samson
- Baylor College of Medicine, St. Luke's Episcopal Hospital, Houston, TX 77030, USA.
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Affiliation(s)
- Carmella Evans-Molina
- Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, Indiana
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana
- Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana
- Corresponding author: Carmella Evans-Molina, , or Raghavendra G. Mirmira,
| | - Raghavendra G. Mirmira
- Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, Indiana
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana
- Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, Indiana
- Department of Pediatrics, Indiana University School of Medicine, Indianapolis, Indiana
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Insulin Sensitivity and Secretion Changes After Gastric Bypass in Normotolerant and Diabetic Obese Subjects. Ann Surg 2013; 257:462-8. [DOI: 10.1097/sla.0b013e318269cf5c] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Bhavsar S, Mudaliar S, Cherrington A. Evolution of exenatide as a diabetes therapeutic. Curr Diabetes Rev 2013; 9:161-93. [PMID: 23256660 PMCID: PMC3664512 DOI: 10.2174/1573399811309020007] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Revised: 12/12/2012] [Accepted: 12/14/2012] [Indexed: 12/18/2022]
Abstract
Type 2 diabetes (T2DM) is a disease of epidemic proportion associated with significant morbidity and excess mortality. Optimal glucose control reduces the risk of microvascular and possibly macrovascular complications due to diabetes. However, glycemic control is rarely optimal and several therapeutic interventions for the treatment of diabetes cause hypoglycemia and weight gain; some may exacerbate cardiovascular risk. Exenatide (synthetic exendin-4) is a glucagon- like peptide-1 receptor (GLP-1R) agonist developed as a first-in-class diabetes therapy. This review presents an overview of the evolution of exenatide as a T2DM treatment, beginning with the seminal preclinical discoveries and continuing through to clinical pharmacology investigations and phase 3 clinical trials. In patients with T2DM, exenatide enhanced glucose-dependent insulin secretion, suppressed inappropriately elevated glucagon secretion, slowed gastric emptying, and enhanced satiety. In controlled phase 3 clinical trials ranging from 12 to 52 weeks, 10-mcg exenatide twice daily (ExBID) reduced mean HbA1c by -0.8% to -1.7% as monotherapy or in combination with metformin (MET), sulfonylureas (SFU), and/or thiazolidinediones (TZD); with mean weight losses of -1.2 kg to -8.0 kg. In controlled phase 3 trials ranging from 24 to 30 weeks, a 2-mg once-weekly exenatide formulation (ExQW) reduced mean HbA1c by -1.3% to -1.9%, with mean weight reductions of -2.3 to -3.7 kg. Exenatide was generally well-tolerated. The most common side effects were gastrointestinal in nature, mild, and transient. Nausea was the most prevalent adverse event. The incidence of hypoglycemia was generally low. By building upon early observations exenatide was successfully developed into an effective diabetes therapy.
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Affiliation(s)
- Sunil Bhavsar
- Amylin Pharmaceuticals, Inc., San Diego CA
- Address correspondence to these authors at the Amylin Pharmaceuticals, Inc., San Diego CA; VA San Diego Healthcare System and University of California at San Diego, San Diego CA; Vanderbilt University, Nashville TN, USA; Fax: 615-343-0490, 858-642-6242; E-mails: , , ,
| | - Sunder Mudaliar
- VA San Diego Healthcare System and University of California at San Diego, San Diego CA
- Address correspondence to these authors at the Amylin Pharmaceuticals, Inc., San Diego CA; VA San Diego Healthcare System and University of California at San Diego, San Diego CA; Vanderbilt University, Nashville TN, USA; Fax: 615-343-0490, 858-642-6242; E-mails: , , ,
| | - Alan Cherrington
- Vanderbilt University, Nashville TN, USA
- Address correspondence to these authors at the Amylin Pharmaceuticals, Inc., San Diego CA; VA San Diego Healthcare System and University of California at San Diego, San Diego CA; Vanderbilt University, Nashville TN, USA; Fax: 615-343-0490, 858-642-6242; E-mails: , , ,
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Jones LH, Price DA. Medicinal chemistry of glucagon-like peptide receptor agonists. PROGRESS IN MEDICINAL CHEMISTRY 2013; 52:45-96. [PMID: 23384666 DOI: 10.1016/b978-0-444-62652-3.00002-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Affiliation(s)
- Lyn H Jones
- BioTherapeutics Chemistry, WorldWide Medicinal Chemistry, Pfizer, Cambridge, MA, USA
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Fineman MS, Cirincione BB, Maggs D, Diamant M. GLP-1 based therapies: differential effects on fasting and postprandial glucose. Diabetes Obes Metab 2012; 14:675-88. [PMID: 22233527 DOI: 10.1111/j.1463-1326.2012.01560.x] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Glucagon-like peptide-1 (GLP-1), a gut-derived hormone secreted in response to nutrients, has several glucose and weight regulating actions including enhancement of glucose-stimulated insulin secretion, suppression of glucagon secretion, slowing of gastric emptying and reduction in food intake. Because of these multiple effects, the GLP-1 receptor system has become an attractive target for type 2 diabetes therapies. However, GLP-1 has significant limitations as a therapeutic due to its rapid degradation (plasma half-life of 1-2 min) by dipeptidyl peptidase-4 (DPP-4). Two main classes of GLP-1-mediated therapies are now in use: DPP-4 inhibitors that reduce the degradation of GLP-1 and DPP-4-resistant GLP-1 receptor (GLP-1R) agonists. The GLP-1R agonists can be further divided into short- and long-acting formulations which have differential effects on their mechanisms of action, ultimately resulting in differential effects on their fasting and postprandial glucose lowering potential. This review summarizes the similarities and differences among DPP-4 inhibitors, short-acting GLP-1R agonists and long-acting GLP-1R agonists. We propose that these different GLP-1-mediated therapies are all necessary tools for the treatment of type 2 diabetes and that the choice of which one to use should depend on the specific needs of the patient. This is analogous to the current use of modern insulins, as short-, intermediate- and long-acting versions are all used to optimize the 24-h plasma glucose profile as needed. Given that GLP-1-mediated therapies have advantages over insulins in terms of hypoglycaemic risk and weight gain, optimized use of these compounds could represent a significant paradigm shift for the treatment of type 2 diabetes.
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Affiliation(s)
- M S Fineman
- Elcelyx Therapeutics, Inc., San Diego, CA, USA.
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Wu D, Yue F, Zou C, Chan P, Alex Zhang Y. Analysis of glucose metabolism in cynomolgus monkeys during aging. Biogerontology 2011; 13:147-55. [PMID: 22057901 DOI: 10.1007/s10522-011-9364-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2011] [Accepted: 10/17/2011] [Indexed: 11/28/2022]
Abstract
This study was designed to investigate the effect of aging on the glucose metabolism on cynomolgus (Macaca fascicularis) monkeys. A total of 33 cynomolgus monkeys in three aged groups were monitored for glucose levels, serum parameters in fasting state and somatometric measurements. Intravenous glucose tolerance test (IVGTT) and insulin tolerance test (ITT) were also performed. Aging associated changes lies in the less secretion of insulin and C-peptide during IVGTT in cynomolgus monkeys. It was also found that impaired insulin sensitivity occurred in female monkeys during aging based on HOMA-IR and K(ITT) value. In addition, triglyceride level also rose with the increase of age. Less insulin secretion and impaired insulin sensitivity in female were the characteristic during the aging of cynomolgus monkeys in this study. Body mass index, weight and waist hip rate may be the relevant factors in insulin resistance of cynomolgus monkeys.
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Affiliation(s)
- Di Wu
- Cell Therapy Center, Beijing Institute of Geriatrics, Xuanwu Hospital, Capital University of Medical Science, People's Republic of China
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Torekov SS, Kipnes MS, Harley RE, Holst JJ, Ehlers MR. Dose response of subcutaneous GLP-1 infusion in patients with type 2 diabetes. Diabetes Obes Metab 2011; 13:639-43. [PMID: 21362122 DOI: 10.1111/j.1463-1326.2011.01388.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AIM To evaluate the dose-response relationship of the recombinant glucagon-like peptide-1 (7-36) amide (rGLP-1) administered by continuous subcutaneous infusion (CSCI) in subjects with type 2 diabetes, with respect to reductions in fasting, postprandial and 11-h serum glucose profiles. METHODS In a double-blind, parallel, placebo-controlled trial, 47 patients were randomized to placebo or rGLP-1 (1.25, 2.5, 5.0 or 8.5 pmol/kg/min) by CSCI for 7 days. On day 1 (pretreatment) and on day 8, patients underwent monitoring of fasting, postprandial, and 11-h profiles of glucose and hormones. RESULTS Fasting serum glucose decreased by 76.2, 53.9, 37.0 and 22.7 mg/dl for the 8.5, 5.0, 2.5 and 1.25 pmol/kg/min rGLP-1 groups, respectively, compared to a decrease of 1.1 mg/dl for placebo (p = 0.0002, 0.005, 0.064 and 0.27, respectively). Mean 11-h serum glucose area under the curve decreased by 36.3, 23.3, 16.9 and 10.0% for 8.5, 5.0, 2.5 and 1.25 pmol/kg/min rGLP-1, respectively, compared to no change for placebo (p = 0.0001, 0.0019, 0.012 and 0.14, respectively). Mean fasting C-peptide increased dose dependently with rGLP-1 (p = 0.0023 for the highest dose) and decreased with placebo. There were no serious safety concerns and no instances of hypoglycaemia. CONCLUSIONS rGLP-1 produced continuous improvements in glycaemic control across a broad dose range of up to 8.5 pmol/kg/min.
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Affiliation(s)
- S S Torekov
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark.
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Seino S, Shibasaki T, Minami K. Dynamics of insulin secretion and the clinical implications for obesity and diabetes. J Clin Invest 2011; 121:2118-25. [PMID: 21633180 DOI: 10.1172/jci45680] [Citation(s) in RCA: 255] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Insulin secretion is a highly dynamic process regulated by various factors including nutrients, hormones, and neuronal inputs. The dynamics of insulin secretion can be studied at different levels: the single β cell, pancreatic islet, whole pancreas, and the intact organism. Studies have begun to analyze cellular and molecular mechanisms underlying dynamics of insulin secretion. This review focuses on our current understanding of the dynamics of insulin secretion in vitro and in vivo and discusses their clinical relevance.
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Affiliation(s)
- Susumu Seino
- Division of Diabetes and Endocrinology, Department of Internal Medicine, Kobe University Graduate School of Medicine, Kobe, Japan.
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Abstract
OBJECTIVE To review available data on preservation and potential improvement of beta-cell function in patients with type 2 diabetes mellitus (T2DM) with use of currently available strategies and agents. METHODS Using key words, we performed a MEDLINE search of the relevant literature published through 2009 regarding the effects of available agents on beta-cell function in humans with T2DM. RESULTS On the basis of current clinical data, no uniformly effective treatment for beta-cell preservation has been found. Lifestyle intervention and early intensive insulin therapy appear to have some preservative properties on beta-cell function. Glucagonlike peptide-1 agonists, dipeptidyl- peptidase-4 inhibitors, and thiazolidinediones result in maintenance and often improvement of beta-cell function during their active use; however, data on their ability to preserve beta-cell function when patients are not receiving active treatment are limited. CONCLUSION The continuous loss of beta-cell mass and beta-cell function is a critical mechanism underlying the progressive deterioration of glycemic control in T2DM. In light of the projected increase in individuals at risk for developing T2DM, strategies and agents aimed at delaying or preventing the progression and inducing a remission of the disease are needed. Future research on this topic should include comparative efficacy trials with washout periods incorporating currently available and novel medications and strategies for preservation of beta cells.
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Affiliation(s)
- Kavita Nyalakonda
- Department of Medicine, Case Western Reserve University, Cleveland, OH, USA
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Abstract
The complex pathological mechanisms responsible for development of type 2 diabetes are not fully addressed by conventional drugs, which are also associated with inconvenient side effects such as weight gain or hypoglycemia. Two types of incretin-based therapies are now in use: incretin mimetics (glucagon-like peptide-1 [GLP-1] receptor agonists that bind specific receptors and mimic the action of natural GLP-1) and incretin enhancers (inhibitors of the enzyme that degrade the incretin hormones and thus prolong their activity). Both offer important advantages over previous agents. In addition to the proven glucose-lowering efficacy, they promote weight loss (or are weight neutral) by slowing gastric emptying and inducing satiety, inhibit glucagon secretion with maintenance of counterregulatory mechanisms, and exhibit cardiovascular benefits, while having a low risk profile. Importantly, short-term studies have shown that incretins/incretin-based therapies protect β-cells (by enhancing cell proliferation and differentiation and inhibiting apoptosis) and stimulate their function (by recruiting β-cells to the secretory process and increasing insulin biosynthesis/secretion). These therapies have the opportunity to interfere with the disease progression if used as an early intervention, when enough β-cell mass/function can still be preserved or restored.
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Affiliation(s)
- Simona Cernea
- Diabetes, Nutrition and Metabolic Diseases Outpatient Unit, Emergency County Clinical Hospital, Târgu Mureş, Romania.
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Chan HM, Jain R, Ahrén B, Pacini G, D'Argenio DZ. Effects of increasing doses of glucagon-like peptide-1 on insulin-releasing phases during intravenous glucose administration in mice. Am J Physiol Regul Integr Comp Physiol 2011; 300:R1126-33. [PMID: 21307364 DOI: 10.1152/ajpregu.00687.2010] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The increase in insulin secretion caused by glucagon-like peptide-1 (GLP-1) and GLP-1 mimetics observed during an intravenous glucose test (IVGTT) has been reported in both normal and disease animal models, as well as in humans. In this study, a hierarchical population modeling approach is used, together with a previously reported model relating glucose to insulin appearance, to determine quantitative in vivo dose-response relationships between GLP-1 dose level and both first- and second-phase insulin release. Parameters of the insulin kinetic model were estimated from the complete set of glucose and insulin data collected in 219 anesthetized nonfasted NMR-imaged mice after intravenous injection of glucose (1 g/kg) alone or with GLP-1 (0.03-100 nmol/kg). The resulting dose-response curves indicate a difference in GLP-1 effect on the two release phases, as is also evident from the different ED(50) parameter values (0.107 vs. 6.65 nmol/kg for phase 1 vs. phase 2 insulin release parameters). The first phase of insulin release is gradually augmented with increasing GLP-1 dose, reaching saturation at a dose of ~1 nmol/kg, while the second-phase release changes more abruptly at GLP-1 doses between 3 and 10 nmol/kg and shows a more pronounced 100-fold increase between control and the high GLP-1 dose of 100 nmol/kg Moreover, separate disposition indices calculated for phase 1 and 2 insulin release, show a different pattern of increase with increasing GLP-1 dose.
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Affiliation(s)
- Hui Min Chan
- Dept. of Biomedical Engineering, University of Southern California, 1042 Downey Way, Los Angeles, CA 90089, USA
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Nauck MA. Incretin-based therapies for type 2 diabetes mellitus: properties, functions, and clinical implications. Am J Med 2011; 124:S3-18. [PMID: 21194578 DOI: 10.1016/j.amjmed.2010.11.002] [Citation(s) in RCA: 218] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The incretin hormones, glucose-dependent insulinotropic polypeptide (GIP) and glucagonlike peptide-1 (GLP-1), which are secreted by cells of the gastrointestinal tract in response to meal ingestion, exercise important glucoregulatory effects, including the glucose-dependent potentiation of insulin secretion by pancreatic β-cells. Research on the defective incretin action in type 2 diabetes mellitus suggests that the observed loss of insulinotropic activity may be due primarily to a decreased responsiveness of β-cells to GIP. GLP-1 does retain efficacy, albeit not at physiologic levels. Accordingly, augmentation of GLP-1 is a logical therapeutic strategy to ameliorate this deficiency, although the short metabolic half-life of the native hormone renders direct infusion impractical. GLP-1 receptor agonists that resist degradation by the enzyme dipeptidyl peptidase-4 (DPP-4) and have protracted-action kinetics have been developed, and DPP-4 inhibitors that slow the enzymatic cleavage of native GLP-1 provide alternative approaches to enhancing incretin-mediated glucose control. However, GLP-1 receptor agonists and DPP-4 inhibitors are premised on highly divergent mechanisms of action. DPP-4 is ubiquitously expressed in many tissues and is involved in a wide range of physiologic processes in addition to its physiologic influence on incretin hormone biological activity. GLP-1 receptor agonists provide a pharmacologic level of GLP-1 receptor stimulation, whereas DPP-4 inhibitors appear to increase levels of circulating GLP-1 to within the physiologic range. This article examines the physiology of the incretin system, mechanistic differences between GLP-1 receptor agonists and DPP-4 inhibitors used as glucose-lowering agents in the treatment of type 2 diabetes, and the implications of these differences for treatment. The results of recent head-to-head trials are reviewed, comparing the effects of incretin-based therapies on a range of clinical parameters, including glycemia, β-cell function, weight, and cardiovascular function.
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Affiliation(s)
- Michael A Nauck
- Bad Lauterberg Diabetes Center, Bad Lauterberg im Harz, Germany.
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Riedel MJ, Kieffer TJ. Treatment of diabetes with glucagon-like peptide-1 gene therapy. Expert Opin Biol Ther 2010; 10:1681-92. [PMID: 21029027 DOI: 10.1517/14712598.2010.532786] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
IMPORTANCE OF THE FIELD Glucagon-like peptide (GLP)-1 receptor agonists are in widespread clinical use for the treatment of diabetes. While effective, these peptides require frequent injections to maintain efficacy. Therefore, alternative delivery methods including gene therapy are currently being evaluated. AREAS COVERED IN THIS REVIEW Here, we review the biology of GLP-1, evidence supporting the clinical use of the native peptide as well as synthetic GLP-1 receptor agonists, and the rationale for their delivery by gene therapy. We then review progress made in the field of GLP-1 gene therapy for both type 1 and type 2 diabetes. WHAT THE READER WILL GAIN Efforts to improve the biological half-life of GLP-1 receptor agonists are discussed. We focus on the development of both viral and non-viral gene delivery methods, highlighting vector designs and the strengths and weaknesses of these approaches. We also discuss the utility of targeting regulated GLP-1 production to tissues including the liver, muscle, islet and gut. TAKE HOME MESSAGE GLP-1 is a natural peptide possessing several actions that effectively combat diabetes. Current delivery methods for GLP-1-based drugs are cumbersome and do not recapitulate the normal secretion pattern of the native hormone. Gene therapy offers a useful method for directing long-term production and secretion of the native peptide. Targeted production of GLP-1 using tissue-specific promoters and delivery methods may improve therapeutic efficacy, while also eliminating the burden of frequent injections.
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Affiliation(s)
- Michael J Riedel
- University of British Columbia, Department of Cellular and Physiological Sciences, Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada
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Pharmacokinetics and Pharmacodynamics of Inhaled GLP-1 (MKC253): Proof-of-Concept Studies in Healthy Normal Volunteers and in Patients With Type 2 Diabetes. Clin Pharmacol Ther 2010; 88:243-50. [DOI: 10.1038/clpt.2010.85] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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