Metformin:A Narrative Review of Its Potential Benefits for Cardiovascular Disease, Cancer and Dementia

The biguanide metformin has been used as first-line therapy in type 2 diabetes mellitus (T2DM) treatment for several decades. In addition to its glucose-lowering properties and its prevention of weight gain, the landmark UK Prospective Diabetes Study (UKPDS) demonstrated cardioprotective properties in obese T2DM patients. Coupled with a favorable side effect profile and low cost, metformin has become the cornerstone in the treatment of T2DM worldwide. In addition, metformin is increasingly being investigated for its potential anticancer and neuroprotective properties both in T2DM patients and non-diabetic individuals. In the meantime, new drugs with powerful cardioprotective properties have been introduced and compete with metformin for its place in the treatment of T2DM. In this review we will discuss actual insights in the various working mechanisms of metformin and the evidence for its beneficial effects on (the prevention of) cardiovascular disease, cancer and dementia. In addition to observational evidence, emphasis is placed on randomized trials and recent meta-analyses to obtain an up-to-date overview of the use of metformin in clinical practice

Microvascular dysfunction as a link between obesity, insulin resistance and hypertension

Impaired microvascular dilatation from any cause and impaired insulin-mediated capillary recruitment in particular result in suboptimal delivery of glucose and insulin to skeletal muscle, and subsequently impairment of glucose disposal (insulin resistance). In addition, microvascular dysfunction, through functional and/or structural arteriolar and capillary drop-out, and arteriolar constriction, increases peripheral resistance and thus blood pressure. Microvascular dysfunction may thus constitute a pathway that links insulin resistance and hypertension. Overweight and obesity may be an important cause of microvascular dysfunction. Mechanisms linking overweight and obesity to microvascular dysfunction include changes in the secretion of adipokines leading to increased levels of free fatty acids and inflammatory mediators, and decreased levels of adiponectin all of which may impair endothelial insulin signaling. Microvascular dysfunction may thus constitute a new treatment target in the prevention of type 2 diabetes mellitus and hypertension

Large Epidemiologic Studies of Gout: Challenges in Diagnosis and Diagnostic Criteria

Large epidemiologic studies of gout can improve insight into the etiology, pathology, impact, and management of the disease. Identification of monosodium urate monohydrate crystals is considered the gold standard for diagnosis, but its application is often not possible in large studies. Therefore, under such circumstances, several proxy approaches are used to classify patients as having gout, including ICD coding in several types of databases or questionnaires that are usually based on the existing classification criteria. However, agreement among these methods is disappointing. Moreover, studies use the terms acute, recurrent, and chronic gout in different ways and without clear definitions. Better definitions of the different manifestations and stages of gout may provide better insight into the natural course and burden of disease and can be the basis for valid approaches to correctly classifying patients within large epidemiologic studies

The association of early life socioeconomic conditions with prediabetes and type 2 diabetes: results from the Maastricht study

markdownabstractBackground: Using cross-sectional data from The Maastricht Study, we examined the association of socioeconomic conditions in early life with prediabetes and T2DM in adulthood. We also examined potential mediating pathways via both adulthood socioeconomic conditions and adult BMI and health behaviours. Methods: Of the 3263 participants (aged 40-75 years), 493 had prediabetes and 906 were diagnosed with T2DM. By using logistic regression analyses, the associations and possible mediating pathways were examined. Results: Participants with low early life socioeconomic conditions had a 1.56 times higher odds of prediabetes (95% confidence interval (CI) = 1.21-2.02) and a 1.61 times higher odds of T2DM (95% CI = 1.31-1.99). The relation between low early life socioeconomic conditions and prediabetes was independent of current socioeconomic conditions (OR = 1.38, 95% CI = 1.05-1.80), whereas the relation with T2DM was not independent of current socioeconomic conditions (OR = 1.10, 95% CI = 0.87-1.37). BMI party mediated the association between early life socioeconomic conditions and prediabetes. Conclusions: Socioeconomic inequalities starting in early life were associated with diabetes-related outcomes in adulthood and suggest the usefulness of early life interventions aimed at tackling these inequalities

Both resistance- and endurance-type exercise reduce the prevalence of hyperglycaemia in individuals with impaired glucose tolerance and in insulin-treated and non-insulin-treated type 2 diabetic patients

Aims/hypothesis The present study compares the impact of endurance- vs resistance-type exercise on subsequent 24 h blood glucose homeostasis in individuals with impaired glucose tolerance (IGT) and type 2 diabetes. Methods Fifteen individuals with IGT, 15 type 2 diabetic patients treated with exogenous insulin (INS), and 15 type 2 diabetic patients treated with oral glucose-lowering medication (OGLM) participated in a randomised crossover experiment. Participants were studied on three occasions for 3 days under strict dietary standardisation, but otherwise free-living conditions. Blood glucose homeostasis was assessed by ambulatory continuous glucose monitoring over the 24 h period following a 45 min session of resistance-type exercise (75% one repetition maximum), endurance-type exercise (50% maximum workload capacity) or no exercise at all. Results Average 24 h blood glucose concentrations were reduced from 7.4±0.2, 9.6±0.5 and 9.2±0.7 mmol/l during the control experiment to 6.9±0.2, 8.6±0.4 and 8.1±0.5 mmol/l (resistance-type exercise) and 6.8±0.2, 8.6±0.5 and 8.5±0.5 mmol/l (endurance-type exercise) over the 24 h period following a single bout of exercise in the IGT, OGLM and INS groups, respectively (p 10 mmol/l) was reduced by 35±7 and 33±11% over the 24 h period following a single session of resistanceand endurance-type exercise, respectively (p< 0.001 for both treatments). Conclusions/interpretation A single session of resistanceor endurance-type exercise substantially reduces the prevalence of hyperglycaemia during the subsequent 24 h period in individuals with IGT, and in insulin-treated and non-insulin-treated type 2 diabetic patients. Both resistance- and endurance-type exercise can be integrated in exercise intervention programmes designed to improve glycaemic control. Trial registration: Clinicaltrials.gov NCT00945165 Funding: The Netherlands Organization for Health Research and Development (ZonMw, the Netherlands). © 2011 The Author(s)

Alterations in Nitric Oxide Activity and Sensitivity in Early Streptozotocin-Induced Diabetes Depend on Arteriolar Size

Changes in NO activity may play an important role in the early increase in microvascular flow that has been implicated in the pathogenesis of diabetic microangiopathy. We assessed, in the in situ spinotrapezius muscle preparation of 6 weeks' streptozotocin-diabetic rats (n = 6) and of agematched controls (n = 8), basal inside diameters of A2–A4 arterioles and the reactivity to topically applied acetylcholine and nitroprusside, before and after NG-nitro-L-arginine. In diabetic rats, cholinergic vasodilatation in A2–A4 arterioles was intact. Basal diameter in A3 and A4 arterioles was significantly higher in streptozotocin-diabetic rats. The increased basal diameter in A3 arterioles was partially due to an increased contribution of NO to basal diameter. The response to nitroprusside was impaired in streptozotocin-diabetic rats in A2, but not in A3 and A4 arterioles. Thus, this study shows that NO activity and sensitivity are altered after 6 weeks of streptozotocin-induced diabetes. These streptozotocin-induced changes are anatomically specific and, for arterioles, depend on their position within the vascular tree

Metformin and high-sensitivity cardiac troponin I and T trajectories in type 2 diabetes patients: a post-hoc analysis of a randomized controlled trial

Background: Metformin has favorable effects on cardiovascular outcomes in both newly onset and advanced type 2 diabetes, as previously reported findings from the UK Prospective Diabetes Study and the HOME trial have demonstrated. Patients with type 2 diabetes present with chronically elevated circulating cardiac troponin levels, an established predictor of cardiovascular endpoints and prognostic marker of subclinical myocardial injury. It is unknown whether metformin affects cardiac troponin levels. The study aimed to evaluate cardiac troponin I and T trajectories in patients with diabetes treated either with metformin or placebo. Methods: This study is a post-hoc analysis of a randomized controlled trial (HOME trial) that included 390 patients with advanced type 2 diabetes randomized to 850 mg metformin or placebo up to three times daily concomitant to continued insulin treatment. Cardiac troponin I and T concentrations were measured at baseline and after 4, 17, 30, 43 and 52 months. We evaluated cardiac troponin trajectories by linear mixed-effects modeling, correcting for age, sex, smoking status and history of cardiovascular disease. Results: This study enrolled 390 subjects, of which 196 received metformin and 194 received placebo. In the treatment and placebo groups, mean age was 64 and 59 years; with 50% and 58% of subjects of the female sex, respectively. Despite the previously reported reduction of macrovascular disease risk in this cohort by metformin, linear mixed-effects regression modelling did not reveal evidence for an effect on cardiac troponin I and cardiac troponin T levels [− 8.4% (− 18.6, 3.2), p = 0.150, and − 4.6% (− 12, 3.2), p = 0.242, respectively]. A statistically significant time-treatment interaction was found for troponin T [− 1.6% (− 2.9, − 0.2), p = 0.021] but not troponin I concentrations [− 1.5% (− 4.2, 1.2), p = 0.263]. Conclusions: In this post-hoc analysis of a 4.3-year randomized controlled trial, metformin did not exert a clinically relevant effect on cardiac troponin I and cardiac troponin T levels when compared to placebo. Cardioprotective effects of the drug observed in clinical studies are not reflected by a reduction in these biomarkers of subclinical myocardial injury. Trial registration ClinicalTrials.gov identifier NCT00375388