Effects of short-term treatment with metformin on markers of endothelial function and inflammatory activity in type 2 diabetes mellitus: a randomized, placebo-controlled trial

Causal association of metformin treatment with diverse cardiovascular diseases: a Mendelian randomization analysis

BACKGROUND

The cardiovascular effects of metformin continue to be a subject of debate within the medical community.

METHODS

The Mendelian randomization (MR) study used data from genome-wide association studies (GWAS) to explore the causal association with six diseases that are associated with bimatoprost treatment and myocardial infarction, chronic heart failure, atrial fibrillation, hypertrophic and dilated cardiomyopathy, and valvular disease. Genome-wide significant single nucleotide polymorphisms (SNPs), that are associated with metformin use were selected as the instrumental variables. To determine the causal relationship between metformin use and various cardiovascular diseases, MR analysis was conducted, employing methods such as Instrumental Variable Weighting (IVW).

RESULTS

The IVW analysis demonstrated a positive association between metformin treatment and the risk of myocardial infarction (OR = 22.67, 95% CI 3.22-34.01; P = 0.002). Conversely, metformin treatment exhibited a negative association with the risk of developing valvular disease (OR = 0.98, 95% CI 0.95-1.00; P = 0.046) and hypertrophic cardiomyopathy (OR = 0.01, 95% CI 0.00-0.22; P = 0.016). Multiple test correction found that metformin treatment was causally associated with the risk of both hypertrophic cardiomyopathy (PFDR = 0.048) and myocardial infarction (PFDR = 0.012). The analysis revealed limited heterogeneity in the individual results, absence of pleiotropy evidence, and indications of stability in the findings.

CONCLUSION

The MR study discovered from a genetic standpoint that metformin may lower the risk of hypertrophic cardiomyopathy and valvular heart disease, yet it could elevate the risk of myocardial infarction.

Exploring metformin monotherapy response in Type-2 diabetes: Computational insights through clinical, genomic, and proteomic markers using machine learning algorithms

BACKGROUND

In 2016, the UK had 4.5 million people with diabetes, predominantly Type-2 Diabetes Mellitus (T2DM). The NHS allocates £10 billion (9% of its budget) to manage diabetes. Metformin is the primary treatment for T2DM, but 35% of patients don't benefit from it, leading to complications. This study aims to delve into metformin's efficacy using clinical, genomic, and proteomic data to uncover new biomarkers and build a Machine Learning predictor for early metformin response detection.

METHODS

Here we report analysis from a T2DM dataset of individuals prescribed metformin monotherapy from the Diastrat cohort recruited at the Altnagelvin Area Hospital, Northern Ireland.

RESULTS

In the clinical data analysis, comparing responders (those achieving HbA1c ≤ 48 mmol/mol) to non-responders (with HbA1c > 48 mmol/mol), we identified that creatinine levels and bodyweight were more negatively correlated with response than non-response. In genomic analysis, we identified statistically significant (p-value <0.05) variants rs6551649 (LPHN3), rs6551654 (LPHN3), rs4495065 (LPHN3) and rs7940817 (TRPC6) which appear to differentiate the responders and non-responders. In proteomic analysis, we identified 15 statistically significant (p-value <0.05, q-value <0.05) proteomic markers that differentiate controls, responders, non-responders and treatment groups, out of which the most significant were HAOX1, CCL17 and PAI that had fold change ∼2. A machine learning model was build; the best model predicted non-responders with 83% classification accuracy.

CONCLUSION

Further testing in prospective validation cohorts is required to determine the clinical utility of the proposed model.

Cellular Senescence, Mitochondrial Dysfunction, and Their Link to Cardiovascular Disease

Cardiovascular diseases (CVDs), a group of disorders affecting the heart or blood vessels, are the primary cause of death worldwide, with an immense impact on patient quality of life and disability. According to the World Health Organization, CVD takes an estimated 17.9 million lives each year, where more than four out of five CVD deaths are due to heart attacks and strokes. In the decades to come, an increased prevalence of age-related CVD, such as atherosclerosis, coronary artery stenosis, myocardial infarction (MI), valvular heart disease, and heart failure (HF) will contribute to an even greater health and economic burden as the global average life expectancy increases and consequently the world's population continues to age. Considering this, it is important to focus our research efforts on understanding the fundamental mechanisms underlying CVD. In this review, we focus on cellular senescence and mitochondrial dysfunction, which have long been established to contribute to CVD. We also assess the recent advances in targeting mitochondrial dysfunction including energy starvation and oxidative stress, mitochondria dynamics imbalance, cell apoptosis, mitophagy, and senescence with a focus on therapies that influence both and therefore perhaps represent strategies with the most clinical potential, range, and utility.

Development of Biotinylated Liposomes Encapsulating Metformin for Therapeutic Targeting of Inflammation-Based Diseases

Inflammation is a physiological response to a damaging stimulus but sometimes can be the cause of the onset of neurodegenerative diseases, atherosclerosis, and cancer. These pathologies are characterized by the overexpression of inflammatory markers like endothelial adhesion molecules, such as Vascular Cell Adhesion Molecule-1 (VCAM-1). In the present work, the development of liposomes for therapeutic targeted delivery to inflamed endothelia is described. The idea is to exploit a three-step pretargeting system based on the biotin-avidin high-affinity interaction: the first step involves a previously described biotin derivative bearing a VCAM-1 binding peptide; in the second step, the avidin derivative NeutrAvidinTM, which strongly binds to the biotin moiety, is injected; the final step is the administration of biotinylated liposomes that would bind to NeutravidinTM immobilized onto VCAM-1 overexpressing endothelium. Stealth biotinylated liposomes, prepared via the thin film hydration method followed by extrusion and purification via size exclusion chromatography, have been thoroughly characterized for their chemico-physical and morphological features and loaded with metformin hydrochloride, a potential anti-inflammatory agent. The three-step system, tested in vitro on different cell lines via confocal microscopy, FACS analysis and metformin uptake, has proved its suitability for therapeutic applications.

The anti-diabetic effects of metformin are mediated by regulating long non-coding RNA

Type 2 diabetes (T2D) is a metabolic disease with complex etiology and mechanisms. Long non-coding ribonucleic acid (LncRNA) is a novel class of functional long RNA molecules that regulate multiple biological functions through various mechanisms. Studies in the past decade have shown that lncRNAs may play an important role in regulating insulin resistance and the progression of T2D. As a widely used biguanide drug, metformin has been used for glucose lowering effects in clinical practice for more than 60 years. For diabetic therapy, metformin reduces glucose absorption from the intestines, lowers hepatic gluconeogenesis, reduces inflammation, and improves insulin sensitivity. However, despite being widely used as the first-line oral antidiabetic drug, its mechanism of action remains largely elusive. Currently, an increasing number of studies have demonstrated that the anti-diabetic effects of metformin were mediated by the regulation of lncRNAs. Metformin-regulated lncRNAs have been shown to participate in the inhibition of gluconeogenesis, regulation of lipid metabolism, and be anti-inflammatory. Thus, this review focuses on the mechanisms of action of metformin in regulating lncRNAs in diabetes, including pathways altered by metformin via targeting lncRNAs, and the potential targets of metformin through modulation of lncRNAs. Knowledge of the mechanisms of lncRNA modulation by metformin in diabetes will aid the development of new therapeutic drugs for T2D in the future.

Roles of mitochondrial dynamics and mitophagy in diabetic myocardial microvascular injury

Myocardial microvessels are composed of a monolayer of endothelial cells, which play a crucial role in maintaining vascular barrier function, luminal latency, vascular tone, and myocardial perfusion. Endothelial dysfunction is a key factor in the development of cardiac microvascular injury and diabetic cardiomyopathy. In addition to their role in glucose oxidation and energy metabolism, mitochondria also participate in non-metabolic processes such as apoptosis, intracellular ion handling, and redox balancing. Mitochondrial dynamics and mitophagy are responsible for regulating the quality and quantity of mitochondria in response to hyperglycemia. However, these endogenous homeostatic mechanisms can both preserve and/or disrupt non-metabolic mitochondrial functions during diabetic endothelial damage and cardiac microvascular injury. This review provides an overview of the molecular features and regulatory mechanisms of mitochondrial dynamics and mitophagy. Furthermore, we summarize findings from various investigations that suggest abnormal mitochondrial dynamics and defective mitophagy contribute to the development of diabetic endothelial dysfunction and myocardial microvascular injury. Finally, we discuss different therapeutic strategies aimed at improving endothelial homeostasis and cardiac microvascular function through the enhancement of mitochondrial dynamics and mitophagy.

Glucose-lowering drugs with cardiovascular benefits as modifiers of critical elements of the human life history

The life history theory assumes that all organisms are under selective pressure to harvest external resources and allocate them to maximise fitness: only organisms making the best use of energy obtain the greatest fitness benefits. The trade-off of energy spans four functions: maintenance, growth, reproduction, and defence against pathogens. The innovative antihyperglycaemic agents glucagon-like peptide 1 (GLP-1) receptor agonists and sodium-glucose cotransporter 2 (SGLT2) inhibitors decrease bodyweight and have the potential to counter low-grade inflammation. These key activities could rewire two components of the life history theory operative in adulthood-ie, maintenance and defence. In this Personal View, we postulate that the benefits of these medications on the cardiovascular system, beyond their glucose-lowering effects, could be mediated by the reduction of the maintenance cost driven by obesity and efforts spent on blunting low-grade inflammation.

Protective effects of metformin in various cardiovascular diseases: Clinical evidence and AMPK-dependent mechanisms

Metformin, a well-known AMPK agonist, has been widely used as the first-line drug for treating type 2 diabetes. There had been a significant concern regarding the use of metformin in people with cardiovascular diseases (CVDs) due to its potential lactic acidosis side effect. Currently growing clinical and preclinical evidence indicates that metformin can lower the incidence of cardiovascular events in diabetic patients or even non-diabetic patients beyond its hypoglycaemic effects. The underlying mechanisms of cardiovascular benefits of metformin largely involve the cellular energy sensor, AMPK, of which activation corrects endothelial dysfunction, reduces oxidative stress and improves inflammatory response. In this minireview, we summarized the clinical evidence of metformin benefits in several widely studied cardiovascular diseases, such as atherosclerosis, ischaemic/reperfusion injury and arrhythmia, both in patients with or without diabetes. Meanwhile, we highlighted the potential AMPK-dependent mechanisms in in vitro and/or in vivo models.

Metformin suppresses pro-inflammatory cytokines in vitreous of diabetes patients and human retinal vascular endothelium

Metformin is a traditional anti-hyperglycemic medication that has recently been shown to benefit vascular complications of diabetes via an anti-inflammatory mechanism other than glycemic control. This study aims to test the hypothesis that metformin suppresses diabetic retinopathy (DR) associated intraocular inflammation. Human vitreous from control and proliferative diabetic retinopathy (PDR) patients with or without long-term metformin treatment (> 5 years) were collected for multiple inflammatory cytokines measurements with a cytokine array kit. The vast majority of the measurable cytokines in PDR vitreous has a lower level in metformin group than non-metformin group. Although the p values are not significant due to a relatively small sample size and large deviations, the 95% confidence interval (CI) for the mean difference between the two groups shows some difference in the true values should not be neglected. Using quantitative ELISA, soluble intercellular adhesion molecule -1 (ICAM-1) and monocyte chemoattractant protein -1 (MCP-1) presented with significantly lower concentrations in metformin group versus non-metformin group. Metformin group also has significantly less up-regulated cytokines and diminished positive correlations among the cytokines when compared to non-metformin group. Possible role of AMP-activated protein kinase (AMPK) and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) in metformin’s anti-inflammatory effects were studied in human retinal vascular endothelial cells (hRVECs) cultured in normal glucose (NG) and high glucose (HG) conditions. Metformin inhibited HG-induced ICAM-1, IL-8, and MCP-1 via AMPK activation, whereas pharmacological AMPK inhibition had no effect on its inhibition of NF-κB p65, sICAM-1, and tumor necrosis factor-α (TNF-α). Metformin-induced suppression of the inflammatory cytokines could also be mediated through its direct inhibition of NF-κB, independent of AMPK pathway. This is a proof-of-concept study that found metformin treatment was associated with reduced inflammatory responses in vitreous of diabetes patients and retinal vascular endothelial cells, supporting the rationale for using metformin to treat DR at an early stage.

Metformin Protects Cardiovascular Health in People With Diabetes

Background

Metformin is the most commonly used drug for patients with diabetes, but there is still some controversy about whether it has a protective effect on cardiovascular health. We therefore used the National Health and Nutritional Examination Survey (NHANES) database to analyze the impact of metformin use on cardiovascular health in patients with diabetes.

Methods

We extracted the demographic data and laboratory test results of all people with diabetes in the NHANES database from January 2017 to March 2020. The outcomes were seven indicators of cardiovascular health from the American Heart Association, each was scored as 0, 1, and 2 to represent poor, moderate, and ideal health statuses, respectively. The scores for the indicators (excluding diet and glycemic status) were summed, and the sum score was then considered to indicate unhealthy (0–5) or healthy (>5). Multivariate logistic regression analysis was used, and subgroup analyses were performed by age, alcohol consumption, education, and marital status.

Results

This study included 1,356 patients with diabetes, among which 606 were taking metformin. After adjusting for all included variables, oral metformin in patients with diabetes had a protective effect on the cardiovascular health of patients (OR = 0.724, 95% CI = 0.573–0.913, P = 0.007). Subgroup analysis indicated that metformin protects the cardiovascular health of people with diabetes more clearly in those who are young (OR = 0.655, 95% CI = 0.481–0.892, P = 0.007), married (OR = 0.633, 95% CI = 0.463–0.863, P = 0.003), and drink alcohol (OR = 0.742, 95% CI = 0.581–0.946, P = 0.016).

Conclusion

This study found that metformin has a protective effect on the cardiovascular health of patients with diabetes. The study findings support the general applicability of metformin.

Metformin and the heart: Update on mechanisms of cardiovascular protection with special reference to comorbid type 2 diabetes and heart failure

Metformin has been in clinical use for the management of type 2 diabetes for more than 60 years and is supported by a vast database of clinical experience: this includes evidence for cardioprotection from randomised trials and real-world studies. Recently, the position of metformin as first choice glucose-lowering agent has been supplanted to some extent by the emergence of newer classes of antidiabetic therapy, namely the sodium-glucose co-transporter-2 (SGLT2) inhibitors and glucagon-like peptide-1 (GLP-1) receptor agonists. These agents have benefitted through support from large cardiovascular outcomes trials with more modern trial designs than earlier studies conducted to assess metformin. Nevertheless, clinical research on metformin continues to further assess its many potentially advantageous effects. Here, we review the evidence for improved cardiovascular outcomes with metformin in the context of the current era of diabetes outcomes trials. Focus is directed towards the potentially cardioprotective actions of metformin in patients with type 2 diabetes and heart failure (HF), now recognised as the most common complication of diabetes.

Metformin in cardiovascular diabetology: a focused review of its impact on endothelial function

As a first-line treatment for diabetes, the insulin-sensitizing biguanide, metformin, regulates glucose levels and positively affects cardiovascular function in patients with diabetes and cardiovascular complications. Endothelial dysfunction (ED) represents the primary pathological change of multiple vascular diseases, because it causes decreased arterial plasticity, increased vascular resistance, reduced tissue perfusion and atherosclerosis. Caused by “biochemical injury”, ED is also an independent predictor of cardiovascular events. Accumulating evidence shows that metformin improves ED through liver kinase B1 (LKB1)/5'-adenosine monophosphat-activated protein kinase (AMPK) and AMPK-independent targets, including nuclear factor-kappa B (NF-κB), phosphatidylinositol 3 kinase-protein kinase B (PI3K-Akt), endothelial nitric oxide synthase (eNOS), sirtuin 1 (SIRT1), forkhead box O1 (FOXO1), krüppel-like factor 4 (KLF4) and krüppel-like factor 2 (KLF2). Evaluating the effects of metformin on endothelial cell functions would facilitate our understanding of the therapeutic potential of metformin in cardiovascular diabetology (including diabetes and its cardiovascular complications). This article reviews the physiological and pathological functions of endothelial cells and the intact endothelium, reviews the latest research of metformin in the treatment of diabetes and related cardiovascular complications, and focuses on the mechanism of action of metformin in regulating endothelial cell functions.

Hypofibrinolysis in type 2 diabetes and its clinical implications: from mechanisms to pharmacological modulation

A prothrombotic state is a typical feature of type 2 diabetes mellitus (T2DM). Apart from increased platelet reactivity, endothelial dysfunction, hyperfibrinogenemia, and hypofibrinolysis are observed in T2DM. A variety of poorly elucidated mechanisms behind impaired fibrinolysis in this disease have been reported, indicating complex associations between platelet activation, fibrin formation and clot structure, and fibrinolysis inhibitors, in particular, elevated plasminogen antigen inhibitor-1 levels which are closely associated with obesity. Abnormal fibrin clot structure is of paramount importance for relative resistance to plasmin-mediated lysis in T2DM. Enhanced thrombin generation, a proinflammatory state, increased release of neutrophil extracellular traps, elevated complement C3, along with posttranslational modifications of fibrinogen and plasminogen have been regarded to contribute to altered clot structure and impaired fibrinolysis in T2DM. Antidiabetic agents such as metformin and insulin, as well as antithrombotic agents, including anticoagulants, have been reported to improve fibrin properties and accelerate fibrinolysis in T2DM. Notably, recent evidence shows that hypofibrinolysis, assessed in plasma-based assays, has a predictive value in terms of cardiovascular events and cardiovascular mortality in T2DM patients. This review presents the current data on the mechanisms underlying arterial and venous thrombotic complications in T2DM patients, with an emphasis on hypofibrinolysis and its impact on clinical outcomes. We also discuss potential modulators of fibrinolysis in the search for optimal therapy in diabetic patients.

Metformin has no impact on nitric oxide production in patients with pre-diabetes

AIMS/INTRODUCTION

The authors evaluated the impact of different dose of metformin on NO (nitric oxide) production in subjects with pre-diabetes.

MATERIALS AND METHODS

The metformin-naïve patients from one Diabetic Center with newly diagnosed pre-diabetes, without cardio-vascular diseases, were randomized (based on the identification number, individual for each inhabitant in the country) for treatment with different doses of metformin (group A 3 × 500 mg, group B 3 × 1000 mg) for 12 weeks. Then, the subjects from group B were switched to dose 3 × 500 for the last 3 weeks. The wide panel of L-arginine/NO pathway metabolites concentrations was assessed using the liquid chromatography-mass spectrometry technique.

RESULTS

Between October 2017 and December 2018, 36 individuals were initially randomized to intervention groups. The study was completed with 25 subjects: 14 patients in group A, 11 in group B; also 11 healthy volunteers were recruited. There was no difference between participants with pre-diabetes and healthy volunteers as regards the baseline characteristics except for fasting glucose and fatty liver. The decrease of L-citrulline concentration only was reported for treatment groups during the intervention period, with no change for the other NO-production related substances.

CONCLUSION

It was the first study on the in vivo release of NO in humans with different metformin doses in patients with pre-diabetes. Metformin did not seem to increase NO production measured by the citrulline plasma levels, irrespective of the dose. The citrulline concentration change might indicate the drug impact on the condition of the enterocytes.

Metformin in the era of new antidiabetics

Type II diabetes mellitus is a known cardiovascular risk factor and its prevalence continues to increase. A revolution in the Type II diabetes mellitus treatment has occurred with the arrival of new antidiabetic drugs, which are thought to compromise metformin place. We aim to review the pharmacology, available evidence and clinical aspects of metformin use in the era of new antidiabetics.

The Current and Potential Therapeutic Use of Metformin-The Good Old Drug

Metformin, one of the oldest oral antidiabetic agents and still recommended by almost all current guidelines as the first-line treatment for type 2 diabetes mellitus (T2DM), has become the medication with steadily increasing potential therapeutic indications. A broad spectrum of experimental and clinical studies showed that metformin has a pleiotropic activity and favorable effect in different pathological conditions, including prediabetes, type 1 diabetes mellitus (T1DM) and gestational diabetes mellitus (GDM). Moreover, there are numerous studies, meta-analyses and population studies indicating that metformin is safe and well tolerated and may be associated with cardioprotective and nephroprotective effect. Recently, it has also been reported in some studies, but not all, that metformin, besides improvement of glucose homeostasis, may possibly reduce the risk of cancer development, inhibit the incidence of neurodegenerative disease and prolong the lifespan. This paper presents some arguments supporting the initiation of metformin in patients with newly diagnosed T2DM, especially those without cardiovascular risk factors or without established cardiovascular disease or advanced kidney insufficiency at the time of new guidelines favoring new drugs with pleotropic effects complimentary to glucose control. Moreover, it focuses on the potential beneficial effects of metformin in patients with T2DM and coexisting chronic diseases.

Effect of Metformin on Circulating Levels of Inflammatory Markers in Patients With Type 2 Diabetes: A Systematic Review and Meta-analysis of Randomized Controlled Trials

BACKGROUND

Emerging evidence indicates that metformin has anti-inflammatory effect; however, the results differ concerning randomized controlled trails of the effect of metformin on inflammatory markers in type 2 diabetes (T2D) patients.

OBJECTIVE

This study reassessed the data on the effect of metformin treatment on inflammatory markers in T2D patients through a systematic review and meta-analysis.

METHODS

A systematic search was performed in the PubMed, ISI Web of Science, EMBASE, Cochrane Library and Scopus databases to collect relevant published data up to September 2020. Data of each study was combined using random-effects model. Subgroup analysis was performed based on subgroups of the treatment duration, dose and target population.

RESULTS

Thirteen RCTs including 1776 participants with T2D were analyzed. Although CRP levels significantly decreased [SMD: -0.76 mg/L; 95% CI (-1.48, -0.049); P = 0.036] in patients with T2D following metformin treatment, circulating levels of TNF-α [SMD: -0.17 pg/mL; 95% CI (-0.55, 0.20); P = 0.37] and IL-6 [SMD: -0.06 pg/mL; 95% CI (-0.38, 0.25); P = 0.69] were insignificant after metformin treatment. Compared to treatment duration of less than 24 weeks, longer treatment duration (more than 24 weeks) was associated with reduced level of CRP.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

Based on available evidence from RCTs in this meta-analysis, metformin decreased CRP level. However, strategies for the treatment of inflammation should focus on metformin in patients with T2D.

CONCLUSION

The present study evidences that therapy with metformin can reduce CRP level significantly in T2D patients compared to other inflammatory markers.

Effect of Metformin on Anthropometric Measurements and Hormonal and Biochemical Profile in Patients with Prediabetes

OBJECTIVES

Metformin is the most widely preferred first-line oral antidiabetic agent that results in clear benefits in blood sugar regulation and diabetes-related complications. This study is aimed at assessing the effect of metformin on anthropometric, hormonal, and biochemical parameters in patients with prediabetes or insulin resistance.

METHODS

A prepoststudy was conducted among 52 patients with prediabetes or insulin resistance who met the inclusion criteria. Weight, body mass index (BMI), and waist circumference were measured before and 12 months after metformin treatment. Serum concentrations of sex steroids, gonadotropins, and lipids were also assessed. Homeostasis model assessment (HOMA) index and quantitative sensitivity check (QUICKI) index scores were calculated before metformin treatment and after 12 months of use.

RESULTS

After 12 months of metformin treatment, female patients had significant reduction in weight, BMI, and waist circumference after adjusting for age. Metformin use for 12 months resulted in significant reduction in mean fasting blood glucose and HbA1c in females only. Total cholesterol decreased significantly among men only and serum HDL-C showed a significant rise among females only. Serum LDL-C and triglycerides did not change significantly in females and males. Our study did now significant changes in ACTH and cortisol levels in both females and males after metformin treatment. Metformin use resulted in significant increase in luteinizing hormone (LH) and progesterone levels in males, while it was associated with significant increase in prolactin, follicular stimulating hormone (FSH), and dehydroepiandrostenedione-sulphate (DHEA-S) levels and significant decrease in total testosterone level in females.

CONCLUSION

Metformin treatment in females with prediabetes reduces BMI, waist circumference, fasting blood glucose, and HbA1c. The changes in the studied parameters differed significantly according to sex.

Role of metformin in various pathologies: state-of-the-art microcapsules for improving its pharmacokinetics

Metformin was originally derived from a botanical ancestry and became the most prescribed, first-line therapy for Type 2 diabetes in most countries. In the last century, metformin was discovered twice for its antiglycemic properties in addition to its antimalarial and anti-influenza effects. Metformin exhibits flip-flop pharmacokinetics with limited oral bioavailability. This review outlines metformin pharmacokinetics, pharmacodynamics and recent advances in polymeric particulate delivery systems as a potential tool to target metformin delivery to specific tissues/organs. This interesting biguanide is being rediscovered this century for multiple clinical indications as anticancer, anti-aging, anti-inflammatory, anti-Alzheimer's and much more. Microparticulate delivery systems of metformin may improve its oral bioavailability and optimize the therapeutic goals expected.

Metformin Preconditioning and Postconditioning to Reduce Ischemia Reperfusion Injury in an Isolated Ex Vivo Rat and Porcine Kidney Normothermic Machine Perfusion Model

Metformin may act renoprotective prior to kidney transplantation by reducing ischemia-reperfusion injury (IRI). This study examined whether metformin preconditioning and postconditioning during ex vivo normothermic machine perfusion (NMP) of rat and porcine kidneys affect IRI. In the rat study, saline or 300 mg/kg metformin was administered orally twice on the day before nephrectomy. After 15 minutes of warm ischemia, kidneys were preserved with static cold storage for 24 hours. Thereafter, 90 minutes of NMP was performed with the addition of saline or metformin (30 or 300 mg/L). In the porcine study, after 30 minutes of warm ischemia, kidneys were preserved for 3 hours with oxygenated hypothermic machine perfusion. Subsequently, increasing doses of metformin were added during 4 hours of NMP. Metformin preconditioning of rat kidneys led to decreased injury perfusate biomarkers and reduced proteinuria. Postconditioning of rat kidneys resulted, dose-dependently, in less tubular cell necrosis and vacuolation. Heat shock protein 70 expression was increased in metformin-treated porcine kidneys. In all studies, creatinine clearance was not affected. In conclusion, both metformin preconditioning and postconditioning can be done safely and improved rat and porcine kidney quality. Because the effects are minor, it is unknown which strategy might result in improved organ quality after transplantation.

Significance of Metformin Use in Diabetic Kidney Disease

Metformin is a glucose-lowering agent that is used as a first-line therapy for type 2 diabetes (T2D). Based on its various pharmacologic actions, the renoprotective effects of metformin have been extensively studied. A series of experimental studies demonstrated that metformin attenuates diabetic kidney disease (DKD) by suppressing renal inflammation, oxidative stress and fibrosis. In clinical studies, metformin use has been shown to be associated with reduced rates of mortality, cardiovascular disease and progression to end-stage renal disease (ESRD) in T2D patients with chronic kidney disease (CKD). However, metformin should be administered with caution to patients with CKD because it may increase the risk of lactic acidosis. In this review article, we summarize our current understanding of the safety and efficacy of metformin for DKD.

Metformin and cardiorenal outcomes in diabetes: A reappraisal

The guidance issued to the pharmaceutical industry by the US Food and Drug Administration in 2008 has led to the publication of a series of randomized, controlled cardiovascular outcomes trials with newer therapeutic classes of glucose-lowering medications. Several of these trials, which evaluated the newer therapeutic classes of sodium-glucose co-transporter-2 inhibitors and glucagon-like peptide-1 receptor agonists, have reported a reduced incidence of major adverse cardiovascular and/or renal outcomes, usually relative to placebo and standard of care. Metformin was the first glucose-lowering agent reported to improve cardiovascular outcomes in the UK Prospective Diabetes Study (UKPDS) and thus became the foundation of standard care. However, as this clinical trial reported more than 20 years ago, differences from current standards of trial design and evaluation complicate comparison of the cardiovascular profiles of older and newer agents. Our article revisits the evidence for cardiovascular protection with metformin and reviews its effects on the kidney.

High fat-induced inflammation in vascular endothelium can be improved by Abelmoschus esculentus and metformin via increasing the expressions of miR-146a and miR-155

Background

Obesity is associated with chronic inflammation, which contributes to cardiovascular diseases. MicroRNAs (miRNAs) are reported to be involved in vascular inflammation and atherosclerosis. Abelmoschus esculentus (AE) and metformin have been suggested to improve inflammation in vascular system. The aim of this study is to evaluate whether miRNAs are involved in high fat induced endothelial inflammation, and whether AE and metformin improve endothelial inflammation by regulating miRNAs.

Methods

We established high fat treated rats and human aortic endothelial cells (HAECs). AE and metformin were added to explore their effects on endothelial inflammation induced by high fat and the possible mechanism.

Results

The vascular inflammatory genes were increased in rats treated with high fat diet. The decreased miR-146a and miR-155 were involved in endothelial inflammation induced by high fat through targeting IL-1 receptor-associated kinase 1 (IRAK1), TNF receptor-associated factor 6 (TRAF6) and nuclear factor-κB p65 (NF-κB p65), respectively. While AE and metformin could ameliorate the endothelial inflammation by increasing miR-146a and miR-155.

Conclusions

These results indicate that miR-146a and miR-155 play roles in the high fat induced endothelial inflammation, which could be potential therapeutic targets. AE and metformin can attenuate endothelial inflammation through regulating miR-146a and miR-155.

Role of Impaired Nutrient and Oxygen Deprivation Signaling and Deficient Autophagic Flux in Diabetic CKD Development: Implications for Understanding the Effects of Sodium-Glucose Cotransporter 2-Inhibitors

Growing evidence indicates that oxidative and endoplasmic reticular stress, which trigger changes in ion channels and inflammatory pathways that may undermine cellular homeostasis and survival, are critical determinants of injury in the diabetic kidney. Cells are normally able to mitigate these cellular stresses by maintaining high levels of autophagy, an intracellular lysosome-dependent degradative pathway that clears the cytoplasm of dysfunctional organelles. However, the capacity for autophagy in both podocytes and renal tubular cells is markedly impaired in type 2 diabetes, and this deficiency contributes importantly to the intensity of renal injury. The primary drivers of autophagy in states of nutrient and oxygen deprivation-sirtuin-1 (SIRT1), AMP-activated protein kinase (AMPK), and hypoxia-inducible factors (HIF-1α and HIF-2α)-can exert renoprotective effects by promoting autophagic flux and by exerting direct effects on sodium transport and inflammasome activation. Type 2 diabetes is characterized by marked suppression of SIRT1 and AMPK, leading to a diminution in autophagic flux in glomerular podocytes and renal tubules and markedly increasing their susceptibility to renal injury. Importantly, because insulin acts to depress autophagic flux, these derangements in nutrient deprivation signaling are not ameliorated by antihyperglycemic drugs that enhance insulin secretion or signaling. Metformin is an established AMPK agonist that can promote autophagy, but its effects on the course of CKD have been demonstrated only in the experimental setting. In contrast, the effects of sodium-glucose cotransporter-2 (SGLT2) inhibitors may be related primarily to enhanced SIRT1 and HIF-2α signaling; this can explain the effects of SGLT2 inhibitors to promote ketonemia and erythrocytosis and potentially underlies their actions to increase autophagy and mute inflammation in the diabetic kidney. These distinctions may contribute importantly to the consistent benefit of SGLT2 inhibitors to slow the deterioration in glomerular function and reduce the risk of ESKD in large-scale randomized clinical trials of patients with type 2 diabetes.

Chronic Adipose Tissue Inflammation Linking Obesity to Insulin Resistance and Type 2 Diabetes

Obesity is one of the major health burdens of the 21st century as it contributes to the growing prevalence of its related comorbidities, including insulin resistance and type 2 diabetes. Growing evidence suggests a critical role for overnutrition in the development of low-grade inflammation. Specifically, chronic inflammation in adipose tissue is considered a crucial risk factor for the development of insulin resistance and type 2 diabetes in obese individuals. The triggers for adipose tissue inflammation are still poorly defined. However, obesity-induced adipose tissue expansion provides a plethora of intrinsic signals (e.g., adipocyte death, hypoxia, and mechanical stress) capable of initiating the inflammatory response. Immune dysregulation in adipose tissue of obese subjects results in a chronic low-grade inflammation characterized by increased infiltration and activation of innate and adaptive immune cells. Macrophages are the most abundant innate immune cells infiltrating and accumulating into adipose tissue of obese individuals; they constitute up to 40% of all adipose tissue cells in obesity. In obesity, adipose tissue macrophages are polarized into pro-inflammatory M1 macrophages and secrete many pro-inflammatory cytokines capable of impairing insulin signaling, therefore promoting the progression of insulin resistance. Besides macrophages, many other immune cells (e.g., dendritic cells, mast cells, neutrophils, B cells, and T cells) reside in adipose tissue during obesity, playing a key role in the development of adipose tissue inflammation and insulin resistance. The association of obesity, adipose tissue inflammation, and metabolic diseases makes inflammatory pathways an appealing target for the treatment of obesity-related metabolic complications. In this review, we summarize the molecular mechanisms responsible for the obesity-induced adipose tissue inflammation and progression toward obesity-associated comorbidities and highlight the current therapeutic strategies.

Metformin alleviates oxidative stress and enhances autophagy in diabetic kidney disease via AMPK/SIRT1-FoxO1 pathway

Metformin, as the basic pharmacological therapy and the first preventive drug in type 2 diabetes mellitus (T2DM), is proved to have potential protection in diabetic kidney disease (DKD). Here, we established a diabetic rat model induced by high-fat diet and low dose streptozotocin, and high glucose cultured rat mesangial cells (RMCs) pre-treated with metformin or transfected with AMPK, SIRT1 and FoxO1 small interfering RNA, and detected oxidative stress and autophagy related factors to explore the molecular mechanisms of metformin on DKD via adenosine monophosphate-activated protein kinase (AMPK)/silent mating type information regulation 2 homolog-1 (sirtuin-1, SIRT1)-Forkhead box protein O1 (FoxO1) pathway. We found that metformin effectively alleviated the disorders of glycolipid metabolism, renal function injury in diabetic rats, and relieved oxidative stress, enhanced autophagy and slowed down abnormal cell proliferation in high glucose cultured RMCs through AMPK/SIRT1-FoxO1 pathway, indicating the protective role of metformin against the pathological process of DKD.

Metformin and Micronutrient Status in Type 2 Diabetes: Does Polypharmacy Involving Acid-Suppressing Medications Affect Vitamin B12 Levels?

Metformin is the first-choice drug in uncomplicated type 2 diabetes (T2DM) and is effective in improving glycaemic control. It is the most widely prescribed oral antidiabetic medicine and has a good safety profile. However, there is an abundance of evidence that metformin use is associated with decreased Vitamin B12 status, though the clinical implications of this in terms of increased risk of diabetic peripheral neuropathy are debated. There is growing evidence that other B vitamins, vitamin D and magnesium may also be impacted by metformin use in addition to alterations to the composition of the microbiome, depending on the dose and duration of therapy. Patients using metformin for prolonged periods may, therefore, need initial screening with intermittent follow-up, particularly since vitamin B₁₂ deficiency has similar symptoms to diabetic neuropathy which itself affects 40-50% of patients with T2DM at some stage. Among patients with T2DM, 40% are reported to experience symptomatic gastroesophageal reflux disease (GORD), of whom 70% use oral antidiabetic medications. The most common medications used to treat GORD are proton pump inhibitors (PPIs) and antagonists of histamine selective H₂ receptors (H₂RAs), both of which independently affect vitamin B₁₂ and magnesium status. Research indicates that co-prescribing metformin with either PPIs or H₂RAs can have further deleterious effects on vitamin B₁₂ status. Vitamin B12 deficiency related to metformin and polypharmacy is likely to contribute to the symptoms of diabetic neuropathy which may frequently be under-recognised. This review explores current knowledge surrounding these issues and suggests treatment strategies such as supplementation.

Vascular adenosine monophosphate-activated protein kinase: Enhancer, brake or both?

Adenosine monophosphate-activated protein kinase (AMPK), expressed/present ubiquitously in the body, contributes to metabolic regulation. In the vasculature, activation of AMPK is associated with several beneficial biological effects including enhancement of vasodilatation, reduction of oxidative stress and inhibition of inflammatory reactions. The vascular protective effects of certain anti-diabetic (metformin and sitagliptin) or lipid-lowering (simvastatin and fenofibrate) therapeutic agents, of active components of Chinese medicinal herbs (resveratrol and berberine) and of pharmacological agents (AICAR, A769662 and PT1) have been attributed to the activation of AMPK (in endothelial cells, vascular smooth muscle cells and/or perivascular adipocytes), independently of changes in the metabolic profile (eg glucose tolerance and/or plasma lipoprotein levels), leading to improved endothelium-derived nitric oxide-mediated vasodilatation and attenuated endothelium-derived cyclooxygenase-dependent vasoconstriction. By contrast, endothelial AMPK activation with pharmacological agents or by genetic modification is associated with reduced endothelium-dependent relaxations in small blood vessels and elevated systolic blood pressure. Indeed, AMPK activators inhibit endothelium-dependent hyperpolarization (EDH)-type relaxations in superior mesenteric arteries, partly by inhibiting endothelial calcium-activated potassium channel signalling. Therefore, AMPK activation is not necessarily beneficial in terms of endothelial function. The contribution of endothelial AMPK in the regulation of vascular tone, in particular in the microvasculature where EDH plays a more important role, remains to be characterized.

Mechanisms of action of metformin with special reference to cardiovascular protection

Management guidelines continue to identify metformin as initial pharmacologic antidiabetic therapy of choice for people with type 2 diabetes without contraindications, despite recent randomized trials that have demonstrated significant improvements in cardiovascular outcomes with newer classes of antidiabetic therapies. The purpose of this review is to summarize the current state of knowledge of metformin's therapeutic actions on blood glucose and cardiovascular clinical evidence and to consider the mechanisms that underlie them. The effects of metformin on glycaemia occur mainly in the liver, but metformin-stimulated glucose disposal by the gut has emerged as an increasingly import site of action of metformin. Additionally, metformin induces increased secretion of GLP-1 from intestinal L-cells. Clinical cardiovascular protection with metformin is supported by three randomized outcomes trials (in newly diagnosed and late stage insulin-treated type 2 diabetes patients) and a wealth of observational data. Initial evidence suggests that cotreatment with metformin may enhance the impact of newer incretin-based therapies on cardiovascular outcomes, an important observation as metformin can be combined with any other antidiabetic agent. Multiple potential mechanisms support the concept of cardiovascular protection with metformin beyond those provided by reduced blood glucose, including weight loss, improvements in haemostatic function, reduced inflammation, and oxidative stress, and inhibition of key steps in the process of atherosclerosis. Accordingly, metformin remains well placed to support improvements in cardiovascular outcomes, from diagnosis and throughout the course of type 2 diabetes, even in this new age of improved outcomes in type 2 diabetes.

Metformin: time to review its role and safety in chronic kidney disease

■Metformin is recommended as first-line therapy for type 2 diabetes because of its safety, low cost and potential cardiovascular benefits. ■The use of metformin was previously restricted in people with chronic kidney disease (CKD) - a condition that commonly coexists with diabetes - due to concerns over drug accumulation and metformin-associated lactic acidosis. ■There are limited data from observational studies and small randomised controlled trials to suggest that metformin, independent of its antihyperglycaemic effects, may be associated with lower risk of myocardial infarction, stroke and all-cause mortality in people with type 2 diabetes and CKD. ■Research into the risk of metformin-associated lactic acidosis in CKD has previously been limited and conflicting, resulting in significant variation across international guidelines on the safe prescribing and dosing of metformin at different stages of renal impairment. ■Present-day large scale cohort studies now provide supporting evidence for the safe use of metformin in mild to moderate renal impairment (estimated glomerular filtration rate [eGFR] 30-60 mL/min/1.73m² ). However, prescribing metformin in people with severe renal impairment (eGFR < 30 mL/min/1.73m² ) remains a controversial issue. Due to observed increased risk of lactic acidosis and all-cause mortality in people with type 2 diabetes and severe renal impairment, it is generally recommended that metformin is discontinued if renal function falls below this level or during acute renal deterioration.

Therapeutic Options Targeting Oxidative Stress, Mitochondrial Dysfunction and Inflammation to Hinder the Progression of Vascular Complications of Diabetes

Type 2 diabetes mellitus is a leading cause of morbidity and mortality worldwide, given its serious associated complications. Despite constant efforts and intensive research, an effective, ubiquitous treatment still eludes the scientific community. As such, the identification of novel avenues of research is key to the potential discovery of this evasive "silver bullet." We focus on this review on the matter of diabetic injury to endothelial tissue and some of the pivotal underlying mechanisms, including hyperglycemia and hyperlipidemia evoked oxidative stress and inflammation. In this sense, we revisited the most promising therapeutic interventions (both non-pharmacological and antidiabetic drugs) targeting oxidative stress and inflammation to hinder progression of vascular complications of diabetes. This review article gives particular attention to the relevance of mitochondrial function, an often ignored and understudied organelle in the vascular endothelium. We highlight the importance of mitochondrial function and number homeostasis in diabetic conditions and discuss the work conducted to address the aforementioned issue by the use of various therapeutic strategies. We explore here the functional, biochemical and bioenergetic alterations provoked by hyperglycemia in the endothelium, from elevated oxidative stress to inflammation and cell death, as well as loss of tissue function. Furthermore, we synthetize the literature regarding the current and promising approaches into dealing with these alterations. We discuss how known agents and therapeutic behaviors (as, for example, metformin, dietary restriction or antioxidants) can restore normality to mitochondrial and endothelial function, preserving the tissue's function and averting the aforementioned complications.

Increased fibulin-1 plasma levels in polycystic ovary syndrome (PCOS) patients: possible contribution to the link between PCOS and cardiovascular risk

PURPOSE

To investigate a possible relation between fibulin-1 plasma levels and PCOS.

DESIGN

ELISA quantitative determination of human fibulin-1.

METHODS

50 women with PCOS and 40 control patients who attended the Unit of Human Reproductive Pathophysiology, Università Cattolica del Sacro Cuore, Rome, were enrolled. Ultrasonographic pelvic examinations, hormonal profile assays, oral tolerance test OGTT, lipid profile and ELISA quantitative determination of human fibulin-1 were performed.

RESULTS

Fibulin-1 levels were found to be statistically significantly higher in PCOS patients than in matched control women. No statistically significant positive correlation was found between fibulin-1 and AUCi, HOMA-IR, total cholesterol, LDL, AMH, androstenedione and FAI, whereas a statistically significant positive correlation was found between fibulin-1 and 17OHP (p = 0.016) in the PCOS group. However, multivariable linear regression analysis showed that 17 OH P did not independently predict fibulin-1 levels (p = 0.089).

CONCLUSIONS

Our data could contribute to explain the hypothesized increased cardiovascular risk and vascular damage in patients with PCOS. A better understanding of the cellular and molecular mechanisms involved in cardiometabolic disorders associated with PCOS is mandatory to identify new therapeutic strategies to eventually prevent the progression of cardiovascular diseases in these patients.

Evidence-based nutritional and pharmacological interventions targeting chronic low-grade inflammation in middle-age and older adults: A systematic review and meta-analysis

Growing evidence suggests chronic low-grade inflammation (LGI) as a possible mechanism underlying the aging process. Some biological and pharmaceutical compounds may reduce systemic inflammation and potentially avert functional decline occurring with aging. The aim of the present meta-analysis was to examine the association of pre-selected interventions on two established biomarkers of inflammation, interleukin-6 (IL-6), and C-reactive protein (CRP) in middle-age and older adults with chronic LGI. We reviewed the literature on potential anti-inflammatory compounds, selecting them based on safety, tolerability, acceptability, innovation, affordability, and evidence from randomized controlled trials. Six compounds met all five inclusion criteria for our systematic review and meta-analysis: angiotensin II receptor blockers (ARBs), metformin, omega-3, probiotics, resveratrol and vitamin D. We searched in MEDLINE, PubMed and EMBASE database until January 2017. A total of 49 articles fulfilled the selection criteria. Effect size of each study and pooled effect size for each compound were measured by the standardized mean difference. I² was computed to measure heterogeneity of effects across studies. The following compounds showed a significant small to large effect in reducing IL-6 levels: probiotics (-0.68 pg/ml), ARBs (-0.37 pg/ml) and omega-3 (-0.19 pg/ml). For CRP, a significant small to medium effect was observed with probiotics (-0.43 mg/L), ARBs (-0.2 mg/L), omega-3 (-0.17 mg/L) and metformin (-0.16 mg/L). Resveratrol and vitamin D were not associated with any significant reductions in either biomarker. These results suggest that nutritional and pharmaceutical compounds can significantly reduce established biomarkers of systemic inflammation in middle-age and older adults. The findings should be interpreted with caution, however, due to the evidence of heterogeneity across the studies.

Intrauterine exposure to metformin: Evaluation of endothelial and perivascular adipose tissue function in abdominal aorta of adult offspring

The biguanide metformin (MET) has been used during pregnancy for treatment of polycystic ovary syndrome and gestational diabetes. MET crosses the placenta and maternal treatment can expose the progeny to this drug during important phases of body development. Direct vascular protective effects have been described with the treatment of metformin. Nevertheless, it is unclear whether intrauterine exposure to metformin is safe for the vascular system of offspring. Thus, the present study aimed to investigate the intrinsic effects of metformin exposure in utero in the offspring abdominal aorta reactivity, in the presence and absence of perivascular adipose tissue (PVAT) and endothelium. For this, Wistar rats were treated with metformin 293 mg/kg/day (MET) or water (CTR) by gavage during the gestational period. The abdominal aorta reactivity to phenylephrine, acetylcholine, and sodium nitroprusside was evaluated in male adult offspring. It was observed that abdominal aorta relaxation was similar between MET and CTR groups in the presence or absence of PVAT. In addition, the contraction to phenylephrine was similar between MET and CTR groups in the presence and absence of PVAT and endothelium. Therefore, metformin exposure during pregnancy had no intrinsic effect on the offspring abdominal aorta PVAT and endothelial function, demonstrating it to be safe to the vascular system of the offspring.

Diabetes, Hypertension, and Cardiovascular Disease: Clinical Insights and Vascular Mechanisms

Hypertension and type 2 diabetes are common comorbidities. Hypertension is twice as frequent in patients with diabetes compared with those who do not have diabetes. Moreover, patients with hypertension often exhibit insulin resistance and are at greater risk of diabetes developing than are normotensive individuals. The major cause of morbidity and mortality in diabetes is cardiovascular disease, which is exacerbated by hypertension. Accordingly, diabetes and hypertension are closely interlinked because of similar risk factors, such as endothelial dysfunction, vascular inflammation, arterial remodelling, atherosclerosis, dyslipidemia, and obesity. There is also substantial overlap in the cardiovascular complications of diabetes and hypertension related primarily to microvascular and macrovascular disease. Common mechanisms, such as upregulation of the renin-angiotensin-aldosterone system, oxidative stress, inflammation, and activation of the immune system likely contribute to the close relationship between diabetes and hypertension. In this article we discuss diabetes and hypertension as comorbidities and discuss the pathophysiological features of vascular complications associated with these conditions. We also highlight some vascular mechanisms that predispose to both conditions, focusing on advanced glycation end products, oxidative stress, inflammation, the immune system, and microRNAs. Finally, we provide some insights into current therapies targeting diabetes and cardiovascular complications and introduce some new agents that may have vasoprotective therapeutic potential in diabetes.

Metformin Use and Severe Dengue in Diabetic Adults

Diabetes mellitus is a risk factor for severe dengue in adults, but few studies have examined the association between metformin use and disease severity in dengue. In addition to its effect on glucose control, metformin has been associated with pleiotropic properties in preclinical studies. Using a cohort of laboratory-confirmed adult (≥21 years) dengue patients with diabetes mellitus admitted to Tan Tock Seng Hospital, we conducted a retrospective cohort study involving 131 (58.7%) metformin users and 92 (41.3%) non-users. Dengue severity was categorized as dengue hemorrhagic fever (DHF) or dengue shock syndrome (DSS) in World Health Organization (WHO) 1997 criteria and severe dengue (SD) in WHO 2009 criteria. Multivariable Poisson regression with robust error variance was used to estimate risk ratio (RR). Compared with non-use, metformin use was associated with a decreased risk of developing severe dengue (adjusted risk ratio [aRR] = 0.60, 95% confidence interval [CI]: 0.37–0.98, P = 0.04). Additionally, there was an inverse dose-response relationship (aRR = 0.69, 95% CI: 0.49–0.98, P = 0.04) with dengue severity as classified by WHO 2009 criteria. Use of metformin, however, was not associated with dengue severity based on WHO 1997 criteria; and no dose-response relationship was noted. Our results suggest metformin use could attenuate disease severity in dengue-infected diabetes mellitus individuals.

Effects of insulin analogs as an add-on to metformin on cutaneous microcirculation in type 2 diabetic patients

BACKGROUND

A single insulin injection was shown to improve microcirculatory blood flow. Our aim was to examine the effects of 4weeks of insulin therapy by three randomly assigned insulin analog regimens (Detemir, Aspart, and their combination) on cutaneous blood flow (CBF) and microcirculatory endothelial function as an add-on to metformin in type 2 diabetic patients poorly controlled on oral antidiabetic treatment.

METHODS

Fourty-two type 2 diabetic patients with no history of cardiovascular disease in secondary failure to oral antidiabetic agents had CBF measurements before and after acetylcholine (Ach) iontophoretic administration. CBF measurements were performed at fasting and after a standardized breakfast during the post-prandial period. Before randomization (Visit 1, V1) during the tests, participants took only metformin. The same tests were repeated after 4weeks of insulin treatment (Visit 2, V2).

RESULTS

Thirty-four patients had good quality recordings for both visits. During V1, CBF and CBF response to Ach increased in the post-prandial period. After 4weeks of insulin treatment, metabolic parameters improved. Compared to V1, CBF at fasting did not increase at V2 but there was an improvement in endothelial function at fasting after Ach iontophoresis, without difference across insulin regimens. Oxidative stress markers were not modified, and E-selectin and vascular cell adhesion molecule 1 levels decreased after insulin treatment, without differences between insulin groups.

CONCLUSIONS

A strategy of improving glycemic control for 4weeks with insulin analogs improves microcirculatory endothelial reactivity and reduces endothelial biomarkers at fasting, whatever the insulin regimen used. Insulin therapy associated to metformin is able to improve fasting microvascular endothelial function even before complete metabolic control.

Metformin for Obesity in Prepubertal and Pubertal Children: A Randomized Controlled Trial

OBJECTIVES

Metformin has shown its effectiveness in treating obesity in adults. However, little research has been conducted in children, with a lack of attention on pubertal status. The objectives were to determine whether oral metformin treatment reduces BMI z score, cardiovascular risk, and inflammation biomarkers in children who are obese depending on pubertal stage and sex.

METHODS

This was a randomized, prospective, double-blind, placebo-controlled, multicenter trial, stratified according to pubertal stage and sex, conducted at 4 Spanish clinical hospitals. Eighty prepubertal and 80 pubertal nondiabetic children who were obese aged 7 to 14 years with a BMI >95th percentiles were recruited. The intervention included 1 g/d of metformin versus placebo for 6 months. The primary outcome was a reduction in BMI z score. Secondary outcomes comprised insulin resistance, cardiovascular risk, and inflammation biomarkers.

RESULTS

A total of 140 children completed the study (72 boys). Metformin decreased the BMI z score versus placebo in the prepubertal group (-0.8 and -0.6, respectively; difference, 0.2; P = .04). Significant increments were observed in prepubertal children treated with metformin versus placebo recipients in the quantitative insulin sensitivity check index (0.010 and -0.007; difference, 0.017; P = .01) and the adiponectin-leptin ratio (0.96 and 0.15; difference, 0.81; P = .01) and declines in interferon-γ (-5.6 and 0; difference, 5.6; P = .02) and total plasminogen activator inhibitor-1 (-1.7 and 2.4; difference, 4.1; P = .04). No serious adverse effects were reported.

CONCLUSIONS

“Metformin decreased the BMI z score and improved inflammatory and cardiovascular-related obesity parameters only in prepubertal children, but a differential effect of metformin was not observed in prepubertal compared to pubertal children. Nevertheless, the doses per kilogram of weight administrated may have had an impact on the metformin effect. Further investigations are necessary.”

Plasma matrix metalloproteinases are associated with incident cardiovascular disease and all-cause mortality in patients with type 1 diabetes: a 12-year follow-up study

Background

Altered regulation of extracellular matrix remodeling by matrix metalloproteinases (MMPs) and tissue inhibitor of metalloproteinase (TIMP) may contribute to vascular complications in type 1 diabetes. We investigated associations between plasma MMP-1, -2, -3, -9, -10 and TIMP-1, and cardiovascular events and all-cause mortality in type 1 diabetic patients.

Methods

We prospectively followed 337 type 1 diabetic patients [mean age 41.4 years (9.6), 39% female], 170 with and 167 without diabetic nephropathy, with median follow-up of 12.3 years. Survival analyses were applied to investigate differences in plasma MMP-1, -2, -3, -9, -10, and TIMP-1-levels in patients with and without a cardiovascular event and in those who died vs survivors. All analyses were adjusted for age, sex, duration of diabetes, HbA1c, nephropathy and for other conventional cardiovascular risk factors.

Results

After adjustment for potential confounders, higher MMP-2 plasma levels were significantly associated with higher incidence of cardiovascular events [HR 1.49 (95% CI 1.11; 1.99)], and higher plasma levels of MMP-1 [1.38 (1.07; 1.78)], MMP-2 [1.60 (1.19; 2.15)] and MMP-3 [1.39 (1.05; 1.85)] were associated with all-cause mortality. All associations were independent of low-grade inflammation and endothelial dysfunction as estimated by plasma markers. Associations between MMP-2 and cardiovascular events and between MMP-3 and mortality were attenuated after further adjustment for eGFR and changes in eGFR.

Conclusions

Higher levels of MMP-2 are associated with CVD and higher MMP-1, -2 and -3 with all-cause mortality. In addition, associations between MMP-2 and CVD, and MMP-3 and mortality were attenuated after adjustment for eGFR while both MMPs were associated with eGFR decline, indicating a possible mediating role of eGFR.

Electronic supplementary material

The online version of this article (doi:10.1186/s12933-017-0539-1) contains supplementary material, which is available to authorized users.

Effect of Metformin on Different Non-Diabetes Related Conditions, a Special Focus on Malignant Conditions: Review of Literature

Metformin has been proven to be one of the most safe and effective antihyperglycemic agents. Through more than six decades of metformin use, it became the most studied hypoglycemic agent; through these studies, it showed a marvelous non-glycemic related effect. These effects include modulation of different points of cancer timeline, weight reduction, cardiovascular health, thyroid diseases, polycystic ovaries disease and many other medical conditions. The aim of this review was to assess the effect of metformin on non-diabetes related medical diseases. We have examined the studies published in PubMed and summarized different randomized controlled trials, observational trials and review articles. This review has summarized most of the non-glycemic effects of metformin. Metformin has been solidly shown to be effective in weight control with certain medications, effective in neuroprotection, in endothelial health, in control of anti-HIV agent side effects and many other crucial health jeopardies. The effects in cancer timeline modulation have taken the biggest part, since it was the most studied area outside the diabetes field. Having mentioned all the above privileges, and in addition to the robust evidence in glycemic control, this consolidates the position of metformin as a first line agent in treatment of diabetes and pre-diabetes. Perhaps in the near future, we may see other indications to use metformin in non-diabetes patients.

Therapeutic approaches targeting inflammation for diabetes and associated cardiovascular risk

Obesity-related sub-acute chronic inflammation has been associated with incident type 2 diabetes and atherosclerotic cardiovascular disease. Inflammation is increasingly considered to be a pathologic mediator of these commonly co-occurring diseases. A growing number of preclinical and clinical studies support the inflammatory hypothesis, but clinical trials to confirm the therapeutic potential to target inflammation to treat or prevent cardiometabolic conditions are still ongoing. There are multiple inflammatory signaling pathways. Regulation is complex, with substantial crosstalk across these multiple pathways. The activity of select pathways may be differentially regulated in different tissues. Pharmacologic approaches to diabetes management may have direct or indirect antiinflammatory effects, the latter potentially attributable to an improved metabolic state. Conversely, some antiinflammatory approaches may affect glucose metabolism and cardiovascular health. To date, clinical trials suggest that targeting one portion of the inflammatory cascade may differentially affect dysglycemia and atherothrombosis. Understanding the underlying biological processes may contribute to the development of safe and effective therapies, although a single approach may not be sufficient for optimal management of both metabolic and athrothrombotic disease states.

Metformin: New Preparations and Nonglycemic Benefits

Metformin has been widely used for over 5 decades. New preparations have been developed for possible enhancement of efficiency, tolerability, and pleiotropic nonglycemic effects. Extended-release metformin has contributed to adherence and improved gastrointestinal tolerability. Delayed-release metformin acts in the lower gastrointestinal tract and exerts glucose-lowering effects at lower plasma metformin levels, which might suggest use of this biguanide in patients with chronic kidney disease. Metformin is also known to have numerous nonglycemic effects. Results of the UK Prospective Diabetes Study indicate improvements in cardiovascular outcome and reduced total mortality independent of glycemic control. Anticancer effects of metformin have been discussed and many clinical trials are on-going. Metformin is noted for its beneficial effects on lifespan extension and on disorders due to increased insulin resistance. Further investigations, including randomized control trials in nondiabetic individuals, are required to demonstrate the nonglycemic effects of metformin.

Metformin in severe exacerbations of chronic obstructive pulmonary disease: a randomised controlled trial

Background

Severe exacerbations of COPD are commonly associated with hyperglycaemia, which predicts adverse outcomes. Metformin is a well-established anti-hyperglycaemic agent in diabetes mellitus, possibly augmented with anti-inflammatory effects, but its effects in COPD are unknown. We investigated accelerated metformin therapy in severe COPD exacerbations, primarily to confirm or refute an anti-hyperglycaemic effect, and secondarily to explore its effects on inflammation and clinical outcome.

Methods

This was a multicentre, randomised, double-blind, placebo-controlled trial testing accelerated metformin therapy in non-diabetic patients, aged ≥35 years, hospitalised for COPD exacerbations. Participants were assigned in a 2:1 ratio to 1 month of metformin therapy, escalated rapidly to 2 g/day, or matched placebo. The primary end point was mean in-hospital blood glucose concentration. Secondary end points included the concentrations of fructosamine and C reactive protein (CRP), and scores on the COPD Assessment Test and Exacerbations of Chronic Pulmonary Disease Tool.

Results

52 participants (mean (±SD) age 67±9 years) were randomised (34 to metformin, 18 to placebo). All were included in the primary end point analysis. The mean blood glucose concentrations in the metformin and placebo groups were 7.1±0.9 and 8.0±3.3 mmol/L, respectively (difference −0.9 mmol/L, 95% CI −2.1 to +0.3; p=0.273). No significant between-group differences were observed on any of the secondary end points. Adverse reactions, particularly gastrointestinal effects, were more common in metformin-treated participants.

Conclusion

Metformin did not ameliorate elevations in blood glucose concentration among non-diabetic patients admitted to hospital for COPD exacerbations, and had no detectable effect on CRP or clinical outcomes.

Trial registration number

ISRCTN66148745 and NCT01247870.

Phenotypic and genetic characteristics of patients with type 2 diabetes with different responses to metformin therapy in Novosibirsk region

Aim: The purpose of this study was to examine the phenotypic and genetic characteristics of patients with type 2 diabetes mellitus (T2DM) with different responses to treatment with metformin (MF) in the Novosibirsk region. Materials and methods: We examined 460 patients with T2DM in the Novosibirsk region. Patients were divided into groups according to their HbA1c level: patients who achieved the target HbA1c level during MF therapy (n = 209) and those who did not reach the target HbA1c level (n=251). Genotyping of ATM (rs11212617) was performed using polymerase chain reaction by TaqMan. Results: Patients who achieved the target HbA1c level during MF treatment (good response) were older (61. 1±9. 1 years vs. 57. 4±8. 4 years, p=0. 001), had later onset of diabetes (54. 6 ± 10. 1 years vs. 49. 2±8. 5 years, p = 0. 0001) and shorter duration of diabetes (6. 5±5. 9 years vs. 8. 2±6. 1 years, p=0. 03) compared with those who did not achieve the target HbA1c level. There was no statistically significant association between ATM rs11212617 and achieving the target HbA1c level among all patients [odds ratio (OR)=0. 94, 95% confidence interval = (0. 73–1. 23), p=0. 67] or those with MF monotherapy [OR=0. 90, (0. 65–1. 25), p=0. 54] or combination therapy [OR=1. 02, (0. 72–1. 43), p=0. 92]. There was an effect of age on response to MF therapy in all three groups (all patients: p=0. 001, MF monotherapy group: p=0. 04, combination therapy group: p=0. 0009). In the MF monotherapy group, low dose MF was associated with a good response (p=0. 03), and in the combination therapy group, males were more likely to have a good response (p=0. 003). Patients with genotype C/C or A/C for ATM (rs11212617) compared with those with genotype A/A were more likely to have high levels of triglycerides [2. 33 (1. 52–4. 2) mmol/l, 2. 09 (1. 35–3. 0) mmol/l and 1. 99 (1. 49–3. 21) mmol/l, respectively, p=0. 001], coronary heart disease (CHD) (13. 4%, 13. 4% and 9. 6%, respectively, p=0. 009) and myocardial infarction (7. 8%, 3. 2% and 4. 0%, respectively, p=0. 001). Conclusion: Patients with T2DM who had a good response to MF therapy were older, more likely to be male and had a later onset of T2DM. Genotype C/C for ATM rs11212617 was associated with high triglycerides, CHD and myocardial infarction. ATM rs11212617 was not associated with response to MF therapy in the Novosibirsk region. 

Effect of six years intensified multifactorial treatment on levels of hs-CRP and adiponectin in patients with screen detected type 2 diabetes: the ADDITION-Netherlands randomized trial

BACKGROUND

Levels of high-sensitivity C-reactive protein (hs-CRP) and adiponectin, reflecting chronic inflammation, are associated with cardiovascular disease in type 2 diabetes. The long-term effects of multifactorial therapy in type 2 diabetes patients on CRP and adiponectin are unknown.

METHODS

The ADDITION-NL study is a randomized clinical trial among screen-detected type 2 diabetes patients, randomized to intensive treatment (HbA1c <7.0% (53 mmol/mol), blood pressure ≤135/85 mmHg, total cholesterol ≤3.5 mmol/L) or routine care. Hs-CRP and adiponectin were measured before and 1, 2 and 6 years after inclusion. We analysed the effectiveness of the intervention on hs-CRP and adiponectin levels using a mixed effects model, taking into account practice, baseline levels and different medications.

RESULTS

A total of 424 patients were included (intensive care n = 235; routine care n = 189). Both groups were well matched. Body mass index, systolic blood pressure, total cholesterol and HbA1c improved significantly more in the intensive care group compared to routine care group. Levels of hs-CRP decreased significantly in both treatment groups over time. Mean hs-CRP in the routine care group was 24% higher (p = 0.0027) than in the intensive treatment group during follow-up. After an initial increase the adiponectin values levelled off to nearly baseline values in both groups. The difference between the two groups after 6 years was 0.44 µg/mL (p = 0.27).

CONCLUSIONS

Intensified multifactorial treatment in type 2 diabetes results in an enhanced decrease in hs-CRP. Whether this is clinically meaningful remains uncertain. The link to adiponectin seems to be more complex.

Crystal structure of bis-{2-[amino(iminium-yl)meth-yl]-1,1-di-methyl-guanidine} carbonate methanol disolvate

In the title solvated mol­ecular salt, 2C₄H₁₂N₅⁺·CO₃²⁻·2CH₃OH, the complete carbonate ion is generated by crystallographic twofold symmetry, with the C atom and one O atom lying on the rotation axis. The cation is twisted about the central C—N bond [C—N—C—N = −137.7 (6)°]. In the crystal, the components are linked by N—H⋯O, N—H⋯N and O—H⋯O hydrogen bonds, generating a three-dimensional supra­molecular network.

Postprandial Dysmetabolism and Oxidative Stress in Type 2 Diabetes: Pathogenetic Mechanisms and Therapeutic Strategies

Postprandial dysmetabolism in type 2 diabetes (T2D) is known to impact the progression and evolution of this complex disease process. However, the underlying pathogenetic mechanisms still require full elucidation to provide guidance for disease prevention and treatment. This review focuses on the marked redox changes and inflammatory stimuli provoked by the spike in blood glucose and lipids in T2D individuals after meals. All the causes of exacerbated postprandial oxidative stress in T2D were analyzed, also considering the consequence of enhanced inflammation on vascular damage. Based on this in-depth analysis, current strategies of prevention and pharmacologic management of T2D were critically reexamined with particular emphasis on their potential redox-related rationale.