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Firth W, Pye KR, Weightman Potter PG. Astrocytes at the intersection of ageing, obesity, and neurodegeneration. Clin Sci (Lond) 2024; 138:515-536. [PMID: 38652065 DOI: 10.1042/cs20230148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Revised: 04/05/2024] [Accepted: 04/09/2024] [Indexed: 04/25/2024]
Abstract
Once considered passive cells of the central nervous system (CNS), glia are now known to actively maintain the CNS parenchyma; in recent years, the evidence for glial functions in CNS physiology and pathophysiology has only grown. Astrocytes, a heterogeneous group of glial cells, play key roles in regulating the metabolic and inflammatory landscape of the CNS and have emerged as potential therapeutic targets for a variety of disorders. This review will outline astrocyte functions in the CNS in healthy ageing, obesity, and neurodegeneration, with a focus on the inflammatory responses and mitochondrial function, and will address therapeutic outlooks.
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Affiliation(s)
- Wyn Firth
- School of Optometry and Vision Sciences, Cardiff University, Cardiff, U.K
| | - Katherine R Pye
- Department of Clinical and Biomedical Sciences, University of Exeter Medical School, Faculty of Health and Life Sciences, University of Exeter, Exeter, U.K
| | - Paul G Weightman Potter
- Department of Clinical and Biomedical Sciences, University of Exeter Medical School, Faculty of Health and Life Sciences, University of Exeter, Exeter, U.K
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2
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Martin DE, Cadar AN, Bartley JM. Old drug, new tricks: the utility of metformin in infection and vaccination responses to influenza and SARS-CoV-2 in older adults. FRONTIERS IN AGING 2023; 4:1272336. [PMID: 37886013 PMCID: PMC10598609 DOI: 10.3389/fragi.2023.1272336] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Accepted: 10/02/2023] [Indexed: 10/28/2023]
Abstract
In the face of global pathogens such as influenza (flu) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), strategies beyond standard vaccines and virus-specific treatments are critically needed for older populations who are more susceptible to severe disease and death from these infections due to age-related immune dysregulation. Thus, complimentary therapeutics are needed to address the increased risk of complications and death in older adults. Metformin, an FDA approved diabetes drug, is an attractive therapeutic candidate to improve immune defenses and resilience in older adults facing viral challenge. Metformin is already a candidate anti-aging drug, but its benefits have potential to span beyond this and improve specific immune responses. Metformin can target multiple aging hallmarks as well as directly impact innate and adaptive immune cell subsets. Both retrospective and prospective studies have demonstrated metformin's efficacy in improving outcomes after SARS-CoV-2 or flu infections. Moreover, evidence from clinical trials has also suggested that metformin treatment can improve vaccination responses. In totality, these findings suggest that metformin can improve age-related declines in immunological resilience. Strategies to improve outcomes after infection or improve vaccine-induced protection are invaluable for older adults. Moreover, the ability to repurpose an already FDA approved drug has significant advantages in terms of necessary time and resources. Thus, metformin has great potential as a therapeutic to improve age-related immune dysregulation during flu and SARS-CoV-2 infections and should be further explored to confirm its ability to improve overall immunological resilience in older adults.
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Metformin and Insulin Resistance: A Review of the Underlying Mechanisms behind Changes in GLUT4-Mediated Glucose Transport. Int J Mol Sci 2022; 23:ijms23031264. [PMID: 35163187 PMCID: PMC8836112 DOI: 10.3390/ijms23031264] [Citation(s) in RCA: 44] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 01/21/2022] [Accepted: 01/21/2022] [Indexed: 02/06/2023] Open
Abstract
Metformin is the most commonly used treatment to increase insulin sensitivity in insulin-resistant (IR) conditions such as diabetes, prediabetes, polycystic ovary syndrome, and obesity. There is a well-documented correlation between glucose transporter 4 (GLUT4) expression and the level of IR. Therefore, the observed increase in peripheral glucose utilization after metformin treatment most likely comes from the induction of GLUT4 expression and its increased translocation to the plasma membrane. However, the mechanisms behind this effect and the critical metformin targets are still largely undefined. The present review explores the evidence for the crucial role of changes in the expression and activation of insulin signaling pathway mediators, AMPK, several GLUT4 translocation mediators, and the effect of posttranscriptional modifications based on previously published preclinical and clinical models of metformin’s mode of action in animal and human studies. Our aim is to provide a comprehensive review of the studies in this field in order to shed some light on the complex interactions between metformin action, GLUT4 expression, GLUT4 translocation, and the observed increase in peripheral insulin sensitivity.
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LaMoia TE, Shulman GI. Cellular and Molecular Mechanisms of Metformin Action. Endocr Rev 2021; 42:77-96. [PMID: 32897388 PMCID: PMC7846086 DOI: 10.1210/endrev/bnaa023] [Citation(s) in RCA: 242] [Impact Index Per Article: 80.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 09/04/2020] [Indexed: 02/07/2023]
Abstract
Metformin is a first-line therapy for the treatment of type 2 diabetes, due to its robust glucose-lowering effects, well-established safety profile, and relatively low cost. While metformin has been shown to have pleotropic effects on glucose metabolism, there is a general consensus that the major glucose-lowering effect in patients with type 2 diabetes is mostly mediated through inhibition of hepatic gluconeogenesis. However, despite decades of research, the mechanism by which metformin inhibits this process is still highly debated. A key reason for these discrepant effects is likely due to the inconsistency in dosage of metformin across studies. Widely studied mechanisms of action, such as complex I inhibition leading to AMPK activation, have only been observed in the context of supra-pharmacological (>1 mM) metformin concentrations, which do not occur in the clinical setting. Thus, these mechanisms have been challenged in recent years and new mechanisms have been proposed. Based on the observation that metformin alters cellular redox balance, a redox-dependent mechanism of action has been described by several groups. Recent studies have shown that clinically relevant (50-100 μM) concentrations of metformin inhibit hepatic gluconeogenesis in a substrate-selective manner both in vitro and in vivo, supporting a redox-dependent mechanism of metformin action. Here, we review the current literature regarding metformin's cellular and molecular mechanisms of action.
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Affiliation(s)
- Traci E LaMoia
- Department of Internal Medicine, Yale School of Medicine, New Haven, Connecticut.,Department of Cellular & Molecular Physiology, Yale School of Medicine, New Haven, Connecticut
| | - Gerald I Shulman
- Department of Internal Medicine, Yale School of Medicine, New Haven, Connecticut.,Department of Cellular & Molecular Physiology, Yale School of Medicine, New Haven, Connecticut
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Calderon G, McRae A, Rievaj J, Davis J, Zandvakili I, Linker-Nord S, Burton D, Roberts G, Reimann F, Gedulin B, Vella A, LaRusso NF, Camilleri M, Gribble FM, Acosta A. Ileo-colonic delivery of conjugated bile acids improves glucose homeostasis via colonic GLP-1-producing enteroendocrine cells in human obesity and diabetes. EBioMedicine 2020; 55:102759. [PMID: 32344198 PMCID: PMC7186521 DOI: 10.1016/j.ebiom.2020.102759] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 03/26/2020] [Accepted: 04/03/2020] [Indexed: 12/12/2022] Open
Abstract
Background The bile acid (BA) pathway plays a role in regulation of food intake and glucose metabolism, based mainly on findings in animal models. Our aim was to determine whether the BA pathway is altered and correctable in human obesity and diabetes. Methods We conducted 3 investigations: 1) BA receptor pathways were studied in NCI-H716 enteroendocrine cell (EEC) line, whole human colonic mucosal tissue and in human colonic EEC isolated by Fluorescence-activated Cell Sorting (ex vivo) from endoscopically-obtained biopsies colon mucosa; 2) We characterized the BA pathway in 307 participants by measuring during fasting and postprandial levels of FGF19, 7αC4 and serum BA; 3) In a placebo-controlled, double-blind, randomised, 28-day trial, we studied the effect of ileo-colonic delivery of conjugated BAs (IC-CBAS) on glucose metabolism, incretins, and lipids, in participants with obesity and diabetes. Findings Human colonic GLP-1-producing EECs express TGR5, and upon treatment with bile acids in vitro, human EEC differentially expressed GLP-1 at the protein and mRNA level. In Ussing Chamber, GLP-1 release was stimulated by Taurocholic acid in either the apical or basolateral compartment. FGF19 was decreased in obesity and diabetes compared to controls. When compared to placebo, IC-CBAS significantly decreased postprandial glucose, fructosamine, fasting insulin, fasting LDL, and postprandial FGF19 and increased postprandial GLP-1 and C-peptide. Increase in faecal BA was associated with weight loss and with decreased fructosamine. Interpretations In humans, BA signalling machinery is expressed in colonic EECs, deficient in obesity and diabetes, and when stimulated with IC-CBAS, improved glucose homeostasis. ClinicalTrials.gov number, NCT02871882, NCT02033876. Funding Research support and drug was provided by Satiogen Pharmaceuticals (San Diego, CA). AA, MC, and NFL report grants (AA- C-Sig P30DK84567, K23 DK114460; MC- NIH R01 DK67071; NFL- R01 DK057993) from the NIH. JR was supported by an Early Career Grant from Society for Endocrinology.
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Affiliation(s)
- Gerardo Calderon
- Clinical Enteric Neuroscience Translational and Epidemiological Research (C.E.N.T.E.R.), Division of Gastroenterology and Hepatology, Mayo Clinic, Charlton 8-142, 200 First St. S.W., Rochester, MN 55905, United States
| | - Alison McRae
- Clinical Enteric Neuroscience Translational and Epidemiological Research (C.E.N.T.E.R.), Division of Gastroenterology and Hepatology, Mayo Clinic, Charlton 8-142, 200 First St. S.W., Rochester, MN 55905, United States
| | - Juraj Rievaj
- University of Cambridge, UK; Current affiliation: Dosage Form Design & Development, AstraZeneca Granta Park, Cambridge CB21 6GH, UK
| | - Judith Davis
- Clinical Enteric Neuroscience Translational and Epidemiological Research (C.E.N.T.E.R.), Division of Gastroenterology and Hepatology, Mayo Clinic, Charlton 8-142, 200 First St. S.W., Rochester, MN 55905, United States
| | - Inuk Zandvakili
- Clinical Enteric Neuroscience Translational and Epidemiological Research (C.E.N.T.E.R.), Division of Gastroenterology and Hepatology, Mayo Clinic, Charlton 8-142, 200 First St. S.W., Rochester, MN 55905, United States
| | - Sara Linker-Nord
- Clinical Enteric Neuroscience Translational and Epidemiological Research (C.E.N.T.E.R.), Division of Gastroenterology and Hepatology, Mayo Clinic, Charlton 8-142, 200 First St. S.W., Rochester, MN 55905, United States
| | - Duane Burton
- Clinical Enteric Neuroscience Translational and Epidemiological Research (C.E.N.T.E.R.), Division of Gastroenterology and Hepatology, Mayo Clinic, Charlton 8-142, 200 First St. S.W., Rochester, MN 55905, United States
| | - Geoffrey Roberts
- Current affiliation: Dosage Form Design & Development, AstraZeneca Granta Park, Cambridge CB21 6GH, UK
| | | | | | - Adrian Vella
- Division of Endocrinology, Department of Medicine, Mayo Clinic, Rochester, MN, United States
| | - Nicholas F LaRusso
- Clinical Enteric Neuroscience Translational and Epidemiological Research (C.E.N.T.E.R.), Division of Gastroenterology and Hepatology, Mayo Clinic, Charlton 8-142, 200 First St. S.W., Rochester, MN 55905, United States
| | - Michael Camilleri
- Clinical Enteric Neuroscience Translational and Epidemiological Research (C.E.N.T.E.R.), Division of Gastroenterology and Hepatology, Mayo Clinic, Charlton 8-142, 200 First St. S.W., Rochester, MN 55905, United States
| | | | - Andres Acosta
- Clinical Enteric Neuroscience Translational and Epidemiological Research (C.E.N.T.E.R.), Division of Gastroenterology and Hepatology, Mayo Clinic, Charlton 8-142, 200 First St. S.W., Rochester, MN 55905, United States.
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Abstract
Metformin has been associated with lactic acidosis. Lactate levels are not commonly tested in clinical practice, and it is unclear to what extent metformin would typically increase lactate levels with chronic use. The aim of this review was to determine whether regular monitoring of the plasma lactate level would be beneficial in avoiding lactate accumulation and, ultimately, minimising the incidence of lactic acidosis in metformin-treated patients.A comprehensive search of PubMed, Embase, Web of Science, Cochrane and International Pharmaceutical Abstracts databases covering the period up to 30 May 2017 was performed. Search terms included combinations of terms and keywords, including "metformin", "lactate", "lactic acid" and "lactic acidosis". Cases series of lactic acidosis or metformin-associated lactic acidosis were excluded.Of 1539 potentially relevant articles, a total of 52 reported lactate levels from routine/regular pathological tests in metformin users. The studies were subdivided into four themes, regarding metformin usage and the reported lactate levels in patients who: (1) did not have contraindications to the use of metformin; (2) had contraindications, or renal impairment but without other contraindications; (3) exercised; or (4) also received any nucleoside reverse transcriptase inhibitor. Studies have reported that metformin treatment could increase lactate level of users. However, most results showed that the lactate level remained in the normal range.No definitive conclusions on the benefits of regular lactate monitoring in patients taking metformin can be made. Future research on larger populations focusing on the measurement of lactate levels with continuous metformin use is warranted.
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Piera-Mardemootoo C, Lambert P, Faillie JL. Efficacy of metformin on glycemic control and weight in drug-naive type 2 diabetes mellitus patients: A systematic review and meta-analysis of placebo-controlled randomized trials. Therapie 2018; 76:647-656. [PMID: 29605144 DOI: 10.1016/j.therap.2018.01.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Revised: 12/04/2017] [Accepted: 01/23/2018] [Indexed: 01/10/2023]
Abstract
AIM OF THE STUDY Metformin is recommended as the first-line treatment of type 2 diabetes mellitus. Despite its common use, few studies have been conducted to precisely measure the efficacy of metformin versus placebo as a first-line treatment. This study aims to assess the precise effects of metformin monotherapy on glycemic control and weight in drug-naive patients with type 2 diabetes mellitus. METHODS Medline® and Cochrane databases were searched until March 19, 2016 to perform a systematic review and meta-analysis of placebo-controlled randomized trials evaluating metformin monotherapy in drug-naive patients with type 2 diabetes mellitus. Assessed outcomes include glycemic control (fasting plasma glucose, glycosated hemoglobin) and weight. RESULTS Overall, 16 studies (1140 patients) were selected. Compared to placebo, metformin monotherapy was associated with decreased glycosated hemoglobin by 0.95% at 3 months (95% CI: 0.50 to 1.39, I2=87%) and 1.32% at 6 months (95% CI: 1.01 to 1.62, I2=71%), and decreased fasting plasma glucose by 1.92mmol/L at 1 month (95% CI: 0.11 to 3.74, I2=88%), 1.79mmol/L at 3 months (95% CI: 0.92 to 2.66, I2=88%) and 2.14mmol/L at 6 months (95% CI: 1.17 to 3.12, I2=82%). No significant difference was demonstrated for the comparisons of weight due to relatively small number of studies retrieved from the literature resulting in insufficient statistical power. CONCLUSION This study provides the precise effects of metformin monotherapy regarding the decreases in fasting plasma glucose and glycosated hemoglobin that physician can expected in drug-naive patients with type 2 diabetes mellitus. No evidence was found for the effects on weight.
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Affiliation(s)
- Carole Piera-Mardemootoo
- Department of general medicine, Faculty of medicine, University of Montpellier, 34295 Montpellier, France
| | - Philippe Lambert
- Department of general medicine, Faculty of medicine, University of Montpellier, 34295 Montpellier, France
| | - Jean-Luc Faillie
- Department of medical pharmacology and toxicology, CHU Montpellier, 34295 Montpellier, France; Laboratory of biostatistics, epidemiology and public health (EA 2415), Faculty of medicine, University of Montpellier, 34295 Montpellier, France.
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Maniar K, Moideen A, Mittal A, Patil A, Chakrabarti A, Banerjee D. A story of metformin-butyrate synergism to control various pathological conditions as a consequence of gut microbiome modification: Genesis of a wonder drug? Pharmacol Res 2016; 117:103-128. [PMID: 27939359 DOI: 10.1016/j.phrs.2016.12.003] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2016] [Revised: 11/25/2016] [Accepted: 12/05/2016] [Indexed: 12/19/2022]
Abstract
The most widely prescribed oral anti-diabetic agent today in the world today is a member of the biguanide class of drugs called metformin. Apart from its use in diabetes, it is currently being investigated for its potential use in many diseases such as cancer, cardiovascular diseases, Alzheimer's disease, obesity, comorbidities of diabetes such as retinopathy, nephropathy to name a few. Numerous in-vitro and in-vivo studies as well as clinical trials have been and are being conducted with a vast amount of literature being published every day. Numerous mechanisms for this drug have been proposed, but they have been unable to explain all the actions observed clinically. It is of interest that insulin has a stimulatory effect on cellular growth. Metformin sensitizes the insulin action but believed to be beneficial in cancer. Like -wise metformin is shown to have beneficial effects in opposite sets of pathological scenario looking from insulin sensitization point of view. This requires a comprehensive review of the disease conditions which are claimed to be affected by metformin therapy. Such a comprehensive review is presently lacking. In this review, we begin by examining the history of metformin before it became the most popular anti-diabetic medication today followed by a review of its relevant molecular mechanisms and important clinical trials in all areas where metformin has been studied and investigated till today. We also review novel mechanistic insight in metformin action in relation to microbiome and elaborate implications of such aspect in various disease states. Finally, we highlight the quandaries and suggest potential solutions which will help the researchers and physicians to channel their research and put this drug to better use.
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Affiliation(s)
- Kunal Maniar
- Department of Pharmacology, Post Graduate Institute of Medical Education & Research, Chandigarh, India
| | - Amal Moideen
- Department of Pharmacology, Post Graduate Institute of Medical Education & Research, Chandigarh, India
| | - Ankur Mittal
- Department of Experimental Medicine & Biotechnology, Post Graduate Institute of Medical Education & Research, Chandigarh, India
| | - Amol Patil
- Department of Pharmacology, Post Graduate Institute of Medical Education & Research, Chandigarh, India
| | - Amitava Chakrabarti
- Department of Pharmacology, Post Graduate Institute of Medical Education & Research, Chandigarh, India
| | - Dibyajyoti Banerjee
- Department of Experimental Medicine & Biotechnology, Post Graduate Institute of Medical Education & Research, Chandigarh, India.
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Saenz A, Fernandez-Esteban I, Mataix A, Ausejo Segura M, Roqué i Figuls M, Moher D. WITHDRAWN: Metformin monotherapy for type 2 diabetes mellitus. Cochrane Database Syst Rev 2015:CD002966. [PMID: 26421423 DOI: 10.1002/14651858.cd002966.pub4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Antonio Saenz
- Centro de Salud Pozuelo 1, INSALUD - Madrid, Emisora s/n, Pozuelo de Alarcón, Madrid, Spain, 28224
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Salpeter SR, Greyber E, Pasternak GA, Salpeter EE. Risk of fatal and nonfatal lactic acidosis with metformin use in type 2 diabetes mellitus. Cochrane Database Syst Rev 2010; 2010:CD002967. [PMID: 20393934 PMCID: PMC7138050 DOI: 10.1002/14651858.cd002967.pub4] [Citation(s) in RCA: 165] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
BACKGROUND Metformin is an oral anti-hyperglycemic agent that has been shown to reduce total mortality compared to other anti-hyperglycemic agents, in the treatment of type 2 diabetes mellitus. Metformin, however, is thought to increase the risk of lactic acidosis, and has been considered to be contraindicated in many chronic hypoxemic conditions that may be associated with lactic acidosis, such as cardiovascular, renal, hepatic and pulmonary disease, and advancing age. OBJECTIVES To assess the incidence of fatal and nonfatal lactic acidosis, and to evaluate blood lactate levels, for those on metformin treatment compared to placebo or non-metformin therapies. SEARCH STRATEGY A comprehensive search was performed of electronic databases to identify studies of metformin treatment. The search was augmented by scanning references of identified articles, and by contacting principal investigators. SELECTION CRITERIA Prospective trials and observational cohort studies in patients with type 2 diabetes of least one month duration were included if they evaluated metformin, alone or in combination with other treatments, compared to placebo or any other glucose-lowering therapy. DATA COLLECTION AND ANALYSIS The incidence of fatal and nonfatal lactic acidosis was recorded as cases per patient-years, for metformin treatment and for non-metformin treatments. The upper limit for the true incidence of cases was calculated using Poisson statistics. In a second analysis lactate levels were measured as a net change from baseline or as mean treatment values (basal and stimulated by food or exercise) for treatment and comparison groups. The pooled results were recorded as a weighted mean difference (WMD) in mmol/L, using the fixed-effect model for continuous data. MAIN RESULTS Pooled data from 347 comparative trials and cohort studies revealed no cases of fatal or nonfatal lactic acidosis in 70,490 patient-years of metformin use or in 55,451 patients-years in the non-metformin group. Using Poisson statistics the upper limit for the true incidence of lactic acidosis per 100,000 patient-years was 4.3 cases in the metformin group and 5.4 cases in the non-metformin group. There was no difference in lactate levels, either as mean treatment levels or as a net change from baseline, for metformin compared to non-metformin therapies. AUTHORS' CONCLUSIONS There is no evidence from prospective comparative trials or from observational cohort studies that metformin is associated with an increased risk of lactic acidosis, or with increased levels of lactate, compared to other anti-hyperglycemic treatments.
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Affiliation(s)
- Shelley R Salpeter
- Stanford University, and Santa Clara Valley Medical CenterMedicine2400 Moorpark Ave, Suite 118San JoseCAUSA95128
| | - Elizabeth Greyber
- Santa Clara Valley Medical CenterMedicine2400 Moorpark Ave, Suite 118San JoseCAUSA95128
| | - Gary A Pasternak
- Santa Clara Valley Medical CenterMedicine2400 Moorpark Ave, Suite 118San JoseCAUSA95128
| | - Edwin E Salpeter
- Cornell UniversityCenter for Radiophysics and Space Research612 Space Sciences BuildingIthacaNYUSA14853
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11
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Salpeter SR, Greyber E, Pasternak GA, Salpeter Posthumous EE. Risk of fatal and nonfatal lactic acidosis with metformin use in type 2 diabetes mellitus. Cochrane Database Syst Rev 2010:CD002967. [PMID: 20091535 DOI: 10.1002/14651858.cd002967.pub3] [Citation(s) in RCA: 165] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
BACKGROUND Metformin is an oral anti-hyperglycemic agent that has been shown to reduce total mortality compared to other anti-hyperglycemic agents, in the treatment of type 2 diabetes mellitus. Metformin, however, is thought to increase the risk of lactic acidosis, and has been considered to be contraindicated in many chronic hypoxemic conditions that may be associated with lactic acidosis, such as cardiovascular, renal, hepatic and pulmonary disease, and advancing age. OBJECTIVES To assess the incidence of fatal and nonfatal lactic acidosis, and to evaluate blood lactate levels, for those on metformin treatment compared to placebo or non-metformin therapies. SEARCH STRATEGY A comprehensive search was performed of electronic databases to identify studies of metformin treatment. The search was augmented by scanning references of identified articles, and by contacting principal investigators. SELECTION CRITERIA Prospective trials and observational cohort studies in patients with type 2 diabetes of least one month duration were included if they evaluated metformin, alone or in combination with other treatments, compared to placebo or any other glucose-lowering therapy. DATA COLLECTION AND ANALYSIS The incidence of fatal and nonfatal lactic acidosis was recorded as cases per patient-years, for metformin treatment and for non-metformin treatments. The upper limit for the true incidence of cases was calculated using Poisson statistics. In a second analysis lactate levels were measured as a net change from baseline or as mean treatment values (basal and stimulated by food or exercise) for treatment and comparison groups. The pooled results were recorded as a weighted mean difference (WMD) in mmol/L, using the fixed-effect model for continuous data. MAIN RESULTS Pooled data from 347 comparative trials and cohort studies revealed no cases of fatal or nonfatal lactic acidosis in 70,490 patient-years of metformin use or in 55,451 patients-years in the non-metformin group. Using Poisson statistics the upper limit for the true incidence of lactic acidosis per 100,000 patient-years was 4.3 cases in the metformin group and 5.4 cases in the non-metformin group. There was no difference in lactate levels, either as mean treatment levels or as a net change from baseline, for metformin compared to non-metformin therapies. AUTHORS' CONCLUSIONS There is no evidence from prospective comparative trials or from observational cohort studies that metformin is associated with an increased risk of lactic acidosis, or with increased levels of lactate, compared to other anti-hyperglycemic treatments.
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Affiliation(s)
- Shelley R Salpeter
- Medicine, Stanford University, and Santa Clara Valley Medical Center, 2400 Moorpark Ave, Suite 118, San Jose, CA, USA, 95128
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12
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Gregorio F, Manfrini S, Testa I, Filipponi P. Metformin treatment in elderly type II diabetic patients. Arch Gerontol Geriatr 2009; 22 Suppl 1:261-70. [PMID: 18653042 DOI: 10.1016/0167-4943(96)86947-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Pharmacological treatment in elderly patients with type II, non-insulin dependent diabetes mellitus (NIDDM) is becoming a growing and complex problem in the clinical practice, since longevity in almost every population is increasing, and the prevalence of NIDDM also rises with age. It is generally indicated that age over 65-70 years represents a specific contraindication against the administration of the biguanides since the risk of the drug-associated lactic acidosis increases with age. However very few data exist in literature about the effect of biguanides, particularly metformin, in aging patients. Therefore, we aimed to evaluate the effects of adding metformin to poorly controlled sulfonylurea-treated elderly diabetic subjects for a one year period. Eighty-four type II diabetic patients aged more than 70 years and with a poor glycemic control were recruited after an informed consent. All diabetic patients were treated with various sulfonylureas at medium doses and presented renal and liver biochemical function tests within normal ranges and were free of severe macroangiopathy and respiratory or congestive heart failure. Metformin treatment was added to the previous sulfonylurea dosages in order to achieve a satisfactory glycemic control. All patients showed a marked improvement in the glycemic control with no significant modification in fasting blood lactate and a mild increase in the post-prandial lactate peak which, however, always felt largely within the normal ranges. Metformin also improved some metabolic vascular risk factors such as plasma cholesterol levels that were reduced, circulating HDL-cholesterol levels that mildly but significantly increased and uric acid that was lowered. In conclusion our data further support the opinion that metformin has not to be denied to diabetic patients on the sole basis of their age.
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Affiliation(s)
- F Gregorio
- Metabolic Unit, Department of Internal Medicine, Pathology and Pharmacology, University of Perugia, Policlinico Monteluce, Via B. Monti, I-06122 Perugia, Italy
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13
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Salpeter S, Greyber E, Pasternak G, Salpeter E. Risk of fatal and nonfatal lactic acidosis with metformin use in type 2 diabetes mellitus. Cochrane Database Syst Rev 2006:CD002967. [PMID: 16437448 DOI: 10.1002/14651858.cd002967.pub2] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
BACKGROUND Metformin is an oral anti-hyperglycemic agent used in the treatment of type 2 diabetes mellitus. The results of the UK Prospective Diabetes Study indicate that metformin treatment is associated with a reduction in total mortality compared to other anti-hyperglycemic treatments. Metformin, however, is thought to increase the risk of lactic acidosis, and is considered to be contraindicated in many chronic hypoxemic conditions that may be associated with lactic acidosis, such as cardiovascular, renal, hepatic and pulmonary disease, and advancing age. OBJECTIVES To assess the incidence of fatal and nonfatal lactic acidosis with metformin use compared to placebo and other glucose-lowering treatments in patients with type 2 diabetes mellitus. A secondary objective was to evaluate the blood lactate levels for those on metformin treatment compared to placebo or non-metformin therapies. SEARCH STRATEGY A search was performed of The Cochrane Library (up to 8/2005), MEDLINE (up to 8/2005), EMBASE (up to 11/2000), OLD MEDLINE, and REACTIONS (up to 8/2005), in order to identify all studies of metformin treatment from 1966 to August 2005. The Cumulated Index Medicus was used to search relevant articles from 1959 to 1965. The search was augmented by scanning references of identified articles, and by contacting principal investigators. Date of latest search: August 2005. SELECTION CRITERIA Prospective trials in patients with type 2 diabetes that lasted longer than one month were included if they evaluated metformin, alone or in combination with other treatments, compared to placebo or any other glucose-lowering therapy. Observational cohort studies of metformin treatment lasting greater than one month were also included. DATA COLLECTION AND ANALYSIS Two reviewers independently selected trials to be included, assessed study quality and extracted data. The incidence of fatal and nonfatal lactic acidosis was recorded as cases per patient-years, for metformin treatment and for placebo or other treatments. The upper limit for the true incidence of cases in the metformin and non-metformin groups were calculated using Poisson statistics. In a second analysis lactate levels were measured as a net change from baseline or as mean treatment values (basal and stimulated by food or exercise) for treatment and comparison groups. The pooled results were recorded as a weighted mean difference (WMD) in mmol/L, using the fixed effect model for continuous data. MAIN RESULTS Pooled data from 206 comparative trials and cohort studies revealed no cases of fatal or nonfatal lactic acidosis in 47,846 patient-years of metformin use or in 38,221 patients-years in the non-metformin group. Using Poisson statistics with 95% confidence intervals the upper limit for the true incidence of metformin-associated lactic acidosis was 6.3 cases per 100,000 patient-years, and the upper limit for the true incidence of lactic acidosis in the non-metformin group was 7.8 cases per 100,000 patient-years. There was no difference in lactate levels, either as mean treatment levels or as a net change from baseline, for metformin compared to placebo or other non-biguanide therapies. The mean lactate levels were slightly lower for metformin treatment compared to phenformin (WMD -0.75 mmol/L, 95% CI -0.86 to -0.15). AUTHORS' CONCLUSIONS There is no evidence from prospective comparative trials or from observational cohort studies that metformin is associated with an increased risk of lactic acidosis, or with increased levels of lactate, compared to other anti-hyperglycemic treatments if prescribed under the study conditions.
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Saenz A, Fernandez-Esteban I, Mataix A, Ausejo M, Roque M, Moher D. Metformin monotherapy for type 2 diabetes mellitus. Cochrane Database Syst Rev 2005:CD002966. [PMID: 16034881 DOI: 10.1002/14651858.cd002966.pub3] [Citation(s) in RCA: 169] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
BACKGROUND Metformin is an anti-hyperglycaemic agent used for the treatment of type 2 diabetes mellitus. Type 2 diabetes may present long-term complications: micro- (retinopathy, nephropathy and neuropathy) and macrovascular (stroke, myocardial infarction and peripheral vascular disease). Two meta-analyses have been published before, although only secondary outcomes were assessed. OBJECTIVES To assess the effects of metformin monotherapy on mortality, morbidity, quality of life, glycaemic control, body weight, lipid levels, blood pressure, insulinaemia, and albuminuria in patients with type 2 diabetes mellitus. SEARCH STRATEGY Studies were obtained from computerised searches of multiple electronic databases and hand searches of reference lists of relevant trials identified. Date of last search: September 2003. SELECTION CRITERIA Trials fulfilling the following inclusion criteria: Diabetes mellitus type 2, metformin versus any other oral intervention, assessment of relevant clinical outcome measures, use of random allocation. DATA COLLECTION AND ANALYSIS Two reviewers extracted data, using a standard data extraction form. Data were summarised under a random effects model. Dichotomous data were expressed as relative risk. We calculated the risk difference (RD), and the Number Needed to Treat, when it was possible. We collected data of mean and standard deviation from changes to baseline. However many trials reported end point data. This limitation lead to the expression of the results as standardised mean differences (SMD) and an overall SMD was calculated. Heterogeneity was tested for using the Z score and the I-squared statistic. Subgroup, sensitivity analysis and meta-regression were used to explore heterogeneity. MAIN RESULTS We included for analysis 29 trials with 37 arms (5259 participants), comparing metformin (37 arms and 2007 participants) with sulphonylureas (13 and 1167), placebo (12 and 702), diet (three and 493), thiazolidinediones (three and 132), insulin (two and 439), meglitinides (two and 208), and glucosidase inhibitors (two and 111). Nine studies reported data on primary outcomes. Obese patients allocated to intensive blood glucose control with metformin showed a greater benefit than chlorpropamide, glibenclamide, or insulin for any diabetes-related outcomes (P = 0.009), and for all-cause mortality (P = 0.03). Obese participants assigned to intensive blood glucose control with metformin showed a greater benefit than overweight patients on conventional treatment for any diabetes-related outcomes (P = 0.004), diabetes-related death (P = 0.03), all-cause mortality (P = 0.01), and myocardial infarction (P = 0.02). Patients assigned to metformin monotherapy showed a significant benefit for glycaemia control, weight, dyslipidaemia, and diastolic blood pressure. Metformin presents a strong benefit for HbA1c when compared with placebo and diet; and a moderated benefit for: glycaemia control, LDL cholesterol, and BMI or weight when compared with sulphonylureas. AUTHORS' CONCLUSIONS Metformin may be the first therapeutic option in the diabetes mellitus type 2 with overweight or obesity, as it may prevent some vascular complications, and mortality. Metformin produces beneficial changes in glycaemia control, and moderated in weight, lipids, insulinaemia and diastolic blood pressure. Sulphonylureas, alpha-glucosidase inhibitors, thiazolidinediones, meglitinides, insulin, and diet fail to show more benefit for glycaemia control, body weight, or lipids, than metformin.
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Affiliation(s)
- A Saenz
- Centro de Salud Pozuelo 1, INSALUD - Madrid, Emisora s/n, Pozuelo de Alarcón, Madrid, Spain, 28224.
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15
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Garber AJ. Metformin: mechanisms of antihyperglycemic action, other pharmacodynamic properties, and safety perspectives. Endocr Pract 2005; 3:359-70. [PMID: 15251775 DOI: 10.4158/ep.3.6.359] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
OBJECTIVE To characterize the mechanisms of action of metformin and describe its effects and safety profile. METHODS Results of more than 30 years of clinical use in countries other than the United States are summarized. In addition, the pharmacologic properties of metformin are compared with those of other antihyperglycemic agents. RESULTS Approximately 90% of all cases of diabetes are non-insulin-dependent diabetes mellitus (NIDDM)--a heterogeneous disease that involves several pathogenic factors and is associated with other coexisting conditions, such as cardiovascular disease, hypertension, and obesity. Thus, an agent that controls blood glucose levels and has favorable effects on the concomitant conditions should be considered when pharmacologic intervention is needed for the treatment of NIDDM. Metformin possesses the pharmacodynamic properties to do both. Its mechanisms of action include the reduction of hepatic glucose production and enhancement of peripheral glucose disposal, making metformin an effective antihyperglycemic agent. It also has other pharmacologic properties, independent of its glycemic effects, that offer additional clinical benefits in comparison with other pharmacologic NIDDM treatments. These benefits include stabilization or even loss of weight in patients for whom weight gain is a concern and reduction of plasma lipid levels in patients with hyperlipidemia. CONCLUSION On the basis of 3 decades of clinical experience, metformin has been shown to be not only a well tolerated but also a highly effective antihyperglycemic agent.
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Affiliation(s)
- A J Garber
- Department of Medicine, Baylor College of Medicine, Houston, Texas 77030, USA
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16
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Salpeter S, Greyber E, Pasternak G, Salpeter E. Risk of fatal and nonfatal lactic acidosis with metformin use in type 2 diabetes mellitus. Cochrane Database Syst Rev 2003:CD002967. [PMID: 12804446 DOI: 10.1002/14651858.cd002967] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND Metformin is an oral anti-hyperglycemic agent used in the treatment of type 2 diabetes mellitus. The results of the UK Prospective Diabetes Study indicate that metformin treatment is associated with a reduction in total mortality compared to other anti-hyperglycemic treatments. Metformin, however, is thought to increase the risk of lactic acidosis, and is considered to be contraindicated in many chronic hypoxemic conditions that may be associated with lactic acidosis, such as cardiovascular, renal, hepatic and pulmonary disease, and advancing age. OBJECTIVES To assess the incidence of fatal and nonfatal lactic acidosis with metformin use compared to placebo and other glucose-lowering treatments in patients with type 2 diabetes mellitus. A secondary objective was to evaluate the blood lactate levels for those on metformin treatment compared to placebo or non-metformin therapies. SEARCH STRATEGY A search was performed of the Cochrane Controlled Trials Register and the Database of Abstracts of Reviews of Effectiveness (up to 4/2000), Medline (up to 11/2000), Embase (up to 11/2000), Oldmedline, and Reactions (up to 5/2000), in order to identify all studies of metformin treatment from 1966 to November 2000. The Cumulated Index Medicus was used to search relevant articles from 1959 to 1965. The search was augmented by scanning references of identified articles, and by contacting principal investigators. Date of latest search: November 2000. SELECTION CRITERIA Prospective trials in patients with type 2 diabetes that lasted longer than one month were included if they evaluated metformin, alone or in combination with other treatments, compared to placebo or any other glucose-lowering therapy. Observational cohort studies of metformin treatment lasting greater than one month were also included. DATA COLLECTION AND ANALYSIS Two reviewers independently selected trials to be included, assessed study quality and extracted data. The incidence of fatal and nonfatal lactic acidosis was recorded as cases per patient-years, for metformin treatment and for placebo or other treatments. The upper limit for the true incidence of cases in the metformin and non-metformin groups were calculated using Poisson statistics. In a second analysis lactate levels were measured as a net change from baseline or as mean treatment values (basal and stimulated by food or exercise) for treatment and comparison groups. The pooled results were recorded as a weighted mean difference (WMD) in mmol/L, using the fixed effects model for continuous data. MAIN RESULTS Pooled data from 176 comparative trials and cohort studies revealed no cases of fatal or nonfatal lactic acidosis in 35,619 patient-years of metformin use or in 30,002 patients-years in the non-metformin group. Using Poisson statistics with 95% confidence intervals the upper limit for the true incidence of metformin-associated lactic acidosis was 8.4 cases per 100,000 patient-years, and the upper limit for the true incidence of lactic acidosis in the non-metformin group was 9 cases per 100,000 patient-years. There was no difference in lactate levels, either as mean treatment levels or as a net change from baseline, for metformin compared to placebo or other non-biguanide therapies. The mean lactate levels were slightly lower for metformin treatment compared to phenformin (WMD -0.75 mmol/L, 95% CI -0.86 to -0.15). REVIEWER'S CONCLUSIONS There is no evidence from prospective comparative trials or from observational cohort studies that metformin is associated with an increased risk of lactic acidosis, or with increased levels of lactate, compared to other anti-hyperglycemic treatments if prescribed under the study conditions, taking into account contra-indications.
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Affiliation(s)
- S Salpeter
- Medicine, Stanford University, and Santa Clara Valley Medical Center, 2400 Moorpark Ave, Suite 118, San Jose, CA 95128, USA.
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17
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Mueller WM, Stanhope KL, Gregoire F, Evans JL, Havel PJ. Effects of metformin and vanadium on leptin secretion from cultured rat adipocytes. OBESITY RESEARCH 2000; 8:530-9. [PMID: 11068959 DOI: 10.1038/oby.2000.66] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
OBJECTIVE We have reported that glucose utilization regulates leptin expression and secretion from isolated rat adipocytes. In this study, we employed two antidiabetic agents that act to increase glucose uptake by peripheral tissues, metformin and vanadium, as pharmacological tools to examine the effects of altering glucose utilization on leptin secretion in primary cultures of rat adipocytes. RESEARCH METHODS AND PROCEDURES Isolated adipocytes (100 microL of packed cells per well) were anchored in a defined matrix of basement membrane components (Matrigel) with media containing 5.5 mM glucose and incubated for 96 hours with metformin or vanadium. Leptin secretion, glucose utilization, and lactate production were assessed. RESULTS Metformin (0.5 and 1.0 mM) increased glucose uptake in the presence of 0.16 nM insulin by 37 +/- 10% (p < 0.005) and 62 +/- 8% (p < 0.0001) over insulin alone, respectively. Metformin from 0.5 to 5.0 mM increased lactate production by 105 +/- 43% (p < 0.025) to 202 +/- 52% (p < 0.0025) and at 1.0 and 5.0 mM increased the proportional rate of glucose conversion to lactate by 78 +/- 18% (p < 0.005) and 166 +/- 41% (p < 0.0025), respectively. At concentrations less than 0.5 mM, metformin did not affect leptin secretion, but at 0.5 mM, the only concentration that significantly increased glucose utilization without increasing glucose conversion to lactate, leptin secretion was modestly stimulated (by 20 +/- 9%; p < 0.05). Concentrations from 1.0 to 25 mM inhibited leptin secretion by 25 +/- 8% (p < 0.005) to 89 +/- 4% (p < 0.0001). Across metformin doses, leptin secretion was inversely related to the percentage of glucose taken up and released as lactate (r = -0.74; p < 0.0001). Vanadium (5 to 20 microM) increased glucose uptake from 20 +/- 7% (p < 0.01) to 34 +/- 13% (p < 0.02) and increased lactate production at 5 microM by 17 +/- 8% (p < 0.025) and 10 microM by 61 +/- 20% (p < 0.02) but did not alter the conversion of glucose to lactate. Vanadium (5 to 50 microM) inhibited leptin secretion by 33 +/- 6% (p < 0.0025) to 61 +/- 8% (p < 0.0001). DISCUSSION Both metformin and vanadium increase glucose uptake and inhibit leptin secretion from cultured adipocytes. The inhibition of leptin secretion by metformin is related to an increase in the metabolism of glucose to lactate. The inhibition by vanadium most likely involves direct effects on cellular phosphatases. We hypothesize that the effect of glucose utilization to stimulate leptin production involves the metabolism of glucose to a fate other than anaerobic lactate production, possibly oxidation or lipogenesis.
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Affiliation(s)
- W M Mueller
- Department of Nutrition, University of California, Davis 95616, USA
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18
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Abstract
Metformin, a dimethylbiguanide, was first synthesized in 1929 and was shown to be a potent hypoglycemic agent. It was rediscovered in 1957 and was widely used in Europe to treat obese type II patients. Metformin resurfaced in the 1980s and was shown to increase insulin sensitivity; this has led to its introduction to clinical practice in the United States for the first time. The small risk of lactic acidosis is now well documented and appropriate therapeutic guidelines have been established. Metformin is a sage and effective drug for management of non-insulin-dependent diabetes mellitus.
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Affiliation(s)
- P M Bell
- Royal Victoria Hospital, Belfast, United Kingdom
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19
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Abstract
Type 2 diabetes mellitus results from impaired insulin secretion and reduced peripheral insulin sensitivity. Treatment options include diet, oral antihyperglycemic agents, and insulin. Metformin, an oral biguanide, ameliorates hyperglycemia by improving peripheral sensitivity to insulin, and reducing gastrointestinal glucose absorption and hepatic glucose production. Unlike sulfonylureas, it does not stimulate insulin secretion, aggravate hyperinsulinemia, or cause hypoglycemia or weight gain (weight stabilizes or decreases). It also has beneficial effects on serum lipid profiles. In lean or overweight type 2 diabetic patients uncontrolled by diet, metformin monotherapy significantly improves glycemic control, compared with placebo, and to similar extents as sulfonylurea monotherapy. In secondary sulfonylurea failure, combination metformin-sulfonylurea treatment significantly improves glycemic control beyond that achieved with either agent along. Metformin-sulfonylurea also appears to be as effective as insulin or insulin plus sulfonylurea, suggesting that such combination therapy may obviate or substantially delay insulin therapy. Limited data suggest that metformin-insulin therapy may improve glycemic control, possibly reducing insulin requirements, in type 2 diabetic patients uncontrolled by insulin alone following secondary sulfonylurea failure. Gastrointestinal side effects are common, but usually tolerated. Lactic acidosis risk is minimal, provided that contraindications, particularly renal impairment, and prescribing guidelines are respected. Aside from elevated plasma metformin levels with cimetidine and synergistic hypoglycemia with sulfonylureas, few interactions occur. Thus, metformin is safe and effective both as monotherapy or in combination with other antihyperglycemic agents in type 2 diabetic patients requiring additional glycemic control and may be advantageous when weight control is desirable and/or hyperlipidemia exists.
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Affiliation(s)
- M B Davidson
- Department of Diabetes, Endocrinology & Metabolism, City of Hope National Medical Center, Duarte, California, USA
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20
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Lunetta M, DiMauro M. Different effect of acute and chronic oral metformin administration on glucose and insulin response to bread and to pasta in non-insulin dependent diabetic patients. Diabetes Res Clin Pract 1996; 33:53-8. [PMID: 8877276 DOI: 10.1016/0168-8227(96)01277-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The aim of the study was to evaluate whether acute and chronic metformin administration may influence differently the glycaemic and insulin response to foods with high and low glycaemic index (bread and pasta) in twelve non-insulin dependent diabetic (NIDDM) patients. Thirty minutes after a random oral administration of either a placebo or a single 850 mg metformin dose, glycaemic and insulin responses to 90 g white bread or 68 g pasta (corresponding to 50 g carbohydrates) were evaluated within 4 h. All the patients were subsequently treated with metformin (850 mg twice a day) for a month and then glycaemic and insulin responses were evaluated again. The acute administration of metformin lowered glycaemic response to bread at 60 and 90 min (P < 0.02 and P < 0.05, respectively) but not to pasta, without affecting insulin response. Chronic metformin treatment significantly lowered glycaemic and insulin response to both bread and pasta. In conclusion, an acute antihyperglycaemic effect of metformin was demonstrable only when a food with high glycaemic index, such as bread, was eaten. On the contrary, the effect of chronic treatment was always present, independent from the glycaemic index of foods, together with a reduction in insulin response, indicating an enhanced sensitivity to endogenous insulin.
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Affiliation(s)
- M Lunetta
- Department of Internal Medicine, Endocrinology and Metabolic Diseases, University of Catania, Italy
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21
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Sasson S, Gorowits N, Joost HG, King GL, Cerasi E, Kaiser N. Regulation by metformin of the hexose transport system in vascular endothelial and smooth muscle cells. Br J Pharmacol 1996; 117:1318-24. [PMID: 8882631 PMCID: PMC1909760 DOI: 10.1111/j.1476-5381.1996.tb16731.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
1. The effect of the biguanide metformin on hexose transport activity was studied in bovine cultured aortic endothelial (BEC) and smooth muscle cells (BSMC). 2. Metformin elevated the rate of hexose transport determined with 2-deoxyglucose (2DG) in a dose- and time-dependent manner in both cell types. Similar ED50 values (0.8-1.0 mM) were determined for the effect of metformin on 2DG uptake in both BEC and BSMC following 24 h exposure to increasing concentrations of metformin, with maximal stimulation at 2 mM. 3. In BEC, metformin increased the hexose transport rate 2-3 fold at all glucose concentrations tested (3.3-22.2 mM). In BSMC incubated with 22.2 mM glucose, metformin elevated the hexose transport approximately 2 fold. The drug was also effective at lower glucose levels, but did not exceed the maximal transport rate observed in glucose-deprived cells. 4. Similar results were obtained when the effect of metformin on hexose transport activity was assessed with the non-metabolizable hexose analogue, 3-O-methylglucose, suggesting that the drug affects primarily the rate of hexose transport rather than its subsequent phosphorylation. 5. The metformin-induced increase in hexose transport in BSMC treated for 24 h with the drug correlated with increased abundance of GLUT1 protein in the plasma membrane, as determined by Western blot analysis. 6. These data indicate that in addition to its known effects on hexose metabolism in insulin responsive tissues, metformin also affects the hexose transport system in vascular cells. This may contribute to its blood glucose lowering capacity in patients with Type 2, non-insulin-dependent diabetes mellitus.
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Affiliation(s)
- S Sasson
- Department of Pharmacology, Hebrew University School of Medicine, Jerusalem, Israel
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22
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Mahler RJ. Metformin: Actions and Indications for Use in Non-Insulin-Dependent Diabetes Mellitus. Endocr Pract 1995; 1:418-22. [PMID: 15251570 DOI: 10.4158/ep.1.6.418] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Metformin (N,N-dimethylbiguanide) is about to be introduced into the United States. The drug, a potent blood glucose-lowering agent, is rapidly absorbed through the small intestine, has a circulating t 1/2 in plasma of 1.7 to 2.5 hours, and is 90% cleared through the kidneys in 12 hours. The drug does not cause hypoglycemia in nondiabetic patients and is effective in both obese and nonobese patients with non-insulin-dependent diabetes mellitus (NIDDM). The drug does not act through stimulation of endogenous insulin secretion. It seems to act at multiple sites, with a small effect on the inhibition of intestinal glucose transport, a moderate effect on inhibition of hepatic glucose output, and a major effect on enhancement of peripheral glucose uptake by muscle and adipose tissues. In addition to its glucose-lowering potency, metformin causes weight loss in obese patients with NIDDM and lowers total cholesterol, very-low-density lipoprotein cholesterol, total triglycerides, and very-low-density lipoprotein triglyceride levels as well as causing an increase in high-density lipoprotein cholesterol level. The drug is ideally suited for obese patients with NIDDM who are unresponsive to diet alone, and it is effective in combination with sulfonylureas. The major risk associated with use of metformin is the development of lactic acidosis. Patients predisposed toward the development of lactic acidosis are those with hepatic or renal disease or with tissue ischemia, in whom the drug should not be prescribed.
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Affiliation(s)
- R J Mahler
- Section of Endocrinology, Cornell University Medical College, New York, New York, USA
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23
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Del Prato S, Marchetto S, Pipitone A, Zanon M, Vigili de Kreutzenberg S, Tiengo A. Metformin and free fatty acid metabolism. DIABETES/METABOLISM REVIEWS 1995; 11 Suppl 1:S33-41. [PMID: 8529483 DOI: 10.1002/dmr.5610110506] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- S Del Prato
- Cattedra di Malattie del Metabolismo, University of Padova, Italy
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24
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Perriello G. Mechanisms of metformin action in non-insulin-dependent diabetes mellitus. DIABETES/METABOLISM REVIEWS 1995; 11 Suppl 1:S51-6. [PMID: 8529485 DOI: 10.1002/dmr.5610110508] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- G Perriello
- Dipartimento di Medicina Interna e Scienze Endocrine e Metaboliche, Università di Perugia, Italy
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25
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Dunn CJ, Peters DH. Metformin. A review of its pharmacological properties and therapeutic use in non-insulin-dependent diabetes mellitus. Drugs 1995; 49:721-49. [PMID: 7601013 DOI: 10.2165/00003495-199549050-00007] [Citation(s) in RCA: 236] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The biguanide metformin (dimethylbiguanide) is an oral antihyperglycaemic agent used in the management of non-insulin-dependent diabetes mellitus (NIDDM). It reduces blood glucose levels, predominantly by improving hepatic and peripheral tissue sensitivity to insulin without affecting the secretion of this hormone. Metformin also appears to have potentially beneficial effects on serum lipid levels and fibrinolytic activity, although the long term clinical implications of these effects are unclear. Metformin possesses similar antihyperglycaemic efficacy to sulphonylureas in obese and nonobese patients with NIDDM. Additionally, interim data from the large multicentre United Kingdom Prospective Diabetes Study (UKPDS) indicated similar antihyperglycaemic efficacy for metformin and insulin in newly diagnosed patients with NIDDM. Unlike the sulphonylureas and insulin, however, metformin treatment is not associated with increased bodyweight. Addition of metformin to existing antidiabetic therapy confers enhanced antihyperglycaemic efficacy. This may be of particular use in improving glycaemic control in patients with NIDDM not adequately controlled with sulphonylurea monotherapy, and may serve to reduce or eliminate the need for daily insulin injections in patients with NIDDM who require this therapy. The acute, reversible gastrointestinal adverse effects seen with metformin may be minimised by administration with or after food, and by using lower dosages, increased slowly where necessary. Lactic acidosis due to metformin is rare, and the risk of this complication may be minimised by observance of prescribing precautions and contraindications intended to avoid accumulation of the drug or lactate in the body. Unlike the sulphonylureas, metformin does not cause hypoglycaemia. Thus, metformin is an effective antihyperglycaemic agent which appears to improve aberrant plasma lipid and fibrinolytic profiles associated with NIDDM. Possible long term clinical benefits of this drug with regard to cardiovascular mortality and morbidity are not yet established but are being assessed in a major ongoing study. Since metformin does not promote weight gain or hypoglycaemia it should be considered first-line pharmacotherapy in obese patients with NIDDM inadequately controlled by nonpharmacological measures. Metformin appears similarly effective for the pharmacological management of NIDDM in nonobese patients.
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Affiliation(s)
- C J Dunn
- Adis International Limited, Auckland, New Zealand
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26
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Johnson AB, Webster JM, Sum CF, Heseltine L, Argyraki M, Cooper BG, Taylor R. The impact of metformin therapy on hepatic glucose production and skeletal muscle glycogen synthase activity in overweight type II diabetic patients. Metabolism 1993; 42:1217-22. [PMID: 8412779 DOI: 10.1016/0026-0495(93)90284-u] [Citation(s) in RCA: 111] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The effect of metformin therapy on glucose metabolism was examined in eight overweight newly presenting untreated type II diabetic patients (five males, three females). Patients were treated for 12 weeks with either metformin (850 mg x 3) or matching placebo using a double-blind crossover study design; patients were studied at presentation and at the end of each treatment period. Insulin action was assessed by measuring activation of skeletal muscle glycogen synthase (GS) before and during a 4-hour hyperinsulinemic euglycemic clamp (100 mU.kg-1 x h-1). Metformin therapy was associated with a significant decrease in fasting blood glucose (6.8 +/- 0.6 v 8.3 +/- 0.9 mmol.L-1, P < .01) and glycosylated hemoglobin ([HbA1] 7.7% +/- 0.4% v 8.5% +/- 0.5%, P < .01) levels. Fasting hepatic glucose production (HGP) was also significantly decreased following metformin therapy (1.98 +/- 0.13 v 2.41 +/- 0.20 mg.kg-1 x min-1, P < .02), whereas fasting insulin and C-peptide concentrations remained unaltered. The decrease in basal HGP correlated closely with the decrease in fasting blood glucose concentration (r = .92, P < .001). Insulin-stimulated glucose uptake was assessed using the hyperinsulinemic euglycemic clamp technique and was increased post-metformin (3.8 +/- 0.6 v 3.1 +/- 0.7 mg.kg-1 x min-1, P < .05). This was primarily the result of increased nonoxidative glucose metabolism (1.1 +/- 0.6 v 0.4 +/- 0.6 mg.kg-1 x min-1, P < .05); oxidative glucose metabolism did not change. Metformin had no measurable effect on insulin activation of skeletal muscle GS, the rate-limiting enzyme controlling muscle glucose storage.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- A B Johnson
- Department of Medicine, Royal Victoria Infirmary, Newcastle-upon-Tyne, UK
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Handberg A, Kayser L, Høyer PE, Voldstedlund M, Hansen HP, Vinten J. Metformin ameliorates diabetes but does not normalize the decreased GLUT 4 content in skeletal muscle of obese (fa/fa) Zucker rats. Diabetologia 1993; 36:481-6. [PMID: 8335168 DOI: 10.1007/bf02743261] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
We studied the expression of the glucose transporter GLUT 4 in the soleus and red gastrocnemius muscles from obese, diabetic (fa/fa) Zucker rats compared to their lean littermates (Fa/-), with and without treatment with the antidiabetic drug metformin. In the untreated groups of rats, the GLUT 4 content in a crude membrane fraction of both the soleus and the red gastrocnemius muscles were significantly lower in the obese (fa/fa) rats (3.46 +/- 0.28 vs. 6.04 +/- 0.41, p < 0.001 and 6.0 +/- 0.24 vs. 9.1 +/- 0.48, p < 0.0001, respectively). Differences in GLUT 4 expression in soleus muscle from the same rats were confirmed by quantitative immunofluorescence microscopy, and the results were significantly correlated with the results obtained from quantitative immunoblotting (rho = 0.70, p < 0.0005). The decreased expression of GLUT 4 in fa/fa rats could contribute to the well-established insulin resistance in skeletal muscle of these animals. After 4 weeks of treatment with metformin, weight gain was not affected in either the diabetic (fa/fa) rats or the lean (Fa/-) rats. Improvement of glucose homeostasis by metformin was not associated with normalization of the GLUT 4 expression in the skeletal muscles studied, indicating (1) that the decreased GLUT 4 expression is not directly related to hyperinsulinaemia and diabetes mellitus and (2) that metformin does not normalize the expression of GLUT 4 in skeletal muscle of the diabetic (fa/fa) Zucker rats.
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Affiliation(s)
- A Handberg
- Institute of Medical Physiology B, Panum Institute, University of Copenhagen, Denmark
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