Metformin use and cardiovascular outcomes after acute myocardial infarction in patients with type 2 diabetes: a cohort study

Preadmission metformin use increased the incidence of hyperlactatemia at admission and 30-day in-hospital mortality among T2D patients with heart disease at high risk of hypoxia

BACKGROUND

Surprisingly, despite the high prevalence of metformin use in type 2 diabetes (T2D) patients with heart disease, limited safety data is available regarding metformin use in patients with acute and critical heart disease.

METHODS

In this single-center retrospective study, patients admitted to the cardiology department for heart failure (HF) or acute coronary syndrome (ACS) between December 2013 and December 2021 and who underwent arterial blood gas analysis at admission with an estimated glomerular clearance rate of ≥45 ml/min/1.73 m2 were identified. The incidences of hyperlactatemia, acidosis, and 30-day in-hospital mortality were compared between preadmission metformin users and nonusers.

RESULTS

Of 526 admissions, 193/193 metformin users/nonusers were selected in a propensity score-matched model. Metformin users had greater lactate levels (2.55 ± 2.07 mmol/l vs. 2.00 ± 1.80 mmol/l P < 0.01), a greater incidence of hyperlactatemia [odds ratio (OR) = 2.55; 95% confidence interval (CI), 1.63-3.98; P < 0.01] and acidosis (OR = 1.78; 95% CI, 1.00-3.16; P < 0.05) at admission and a greater incidence of in-hospital mortality (OR = 3.83; 95% CI, 1.05-13.94; P < 0.05), especially those with HF/acute myocardial infarction, elderly age, or without preadmission insulin use.

CONCLUSIONS

Our results suggest that, compared to metformin nonusers, preadmission use of metformin may be associated with a greater incidence of hyperlactatemia and acidosis at admission and greater 30-day in-hospital mortality among T2D patients with HF or ACS at high risk of hypoxia, particularly those without preadmission insulin use. The safety of metformin in this population needs to be confirmed in prospective controlled trials.

Clinical efficacy and cost-effectiveness of metformin in different patient populations: A narrative review of real-world evidence

Over the past two decades, diabetes pharmacopoeia has flourished, with new drugs that, on top of their glucose-lowering efficacy, have been shown to protect the heart and the kidney. Despite these new opportunities, metformin retains a pivotal role among glucose-lowering agents. As one of the few available insulin sensitizers, metformin is an effective, safe, and overall well-tolerated drug backed by over 60 years of clinical experience, including evidence for potential benefits beyond glucose reduction across different ages, sexes, genetic backgrounds, geographical areas, and stages of disease. Although there is some discussion of whether metformin offers the most effective front-line option in newly diagnosed type 2 diabetes (T2D), it remains a natural companion to all other glucose-lowering agents. Furthermore, metformin comes at a very low cost and, as such, it has extremely high cost-effectiveness, particularly given the serious economic burden associated with diabetes complications. This financial advantage is particularly relevant in resource-constrained healthcare systems, where the affordability of metformin may be instrumental in implementing an effective treatment in an evergrowing number of individuals. We present here compelling real-world evidence in support of the clinical efficacy and cost-effectiveness of metformin across different patient populations, highlighting areas where more population-based studies are needed to further incorporate and consolidate its use in the pharmacological management of T2D.

Unraveling genetic causality between metformin and myocardial infarction on the basis of Mendelian randomization

Background

In recent years, several studies have explored the effect of metformin on myocardial infarction (MI), but whether metformin has an improvement effect in patients with MI is controversial. This study was aimed to investigate the causal relationship between metformin and MI using Mendelian randomization (MR) analysis.

Methods

The genome-wide significant (P<5×10-8) single-nucleotide polymorphisms (SNPs) in patients with metformin and patients with MI were screened from the Open genome-wide association study (GWAS) project as instrumental variables (IVs). The study outcomes mainly included MI, old MI, acute MI, acute transmural MI of inferior wall, and acute transmural MI of anterior wall. The inverse variance weighted (IVW) method was applied to assess the main causal effect, and weighted median, simple mode, weighted mode methods, and MR-Egger regression were auxiliary applied for supplementary proof. The causal relationship between metformin and MI was assessed using odds ratios (OR) and 95% confidence intervals (95% CI). A leave-one-out method was used to explore the effect of individual SNPs on the results of IVW analyses, and a funnel plot was used to analyze the potential bias of the study results, thus ensuring the robustness of the results.

Results

In total, 16, 84, 39, 26, and 34 SNPs were selected as IVs to assess the genetic association between metformin and outcomes of MI, old MI, acute MI, acute transmural MI of inferior wall, and acute transmural MI of anterior wall, respectively. Treatment with metformin does not affect the risk of acute transmural MI of anterior wall at the genetic level (P>0.05; OR for inverse variance weighted was 1.010). In the cases of MI, old MI, acute MI, and acute transmural MI of inferior wall, metformin may even be a risk factor for patients (P<0.05; ORs for inverse variance weighted were 1.078, 1.026, 1.022 and 1.018 respectively). There was no horizontal pleiotropy or heterogeneity among IVs. The results were stable when removing the SNPs one by one.

Conclusion

Metformin is not protective against the risk of myocardial infarction in patients and may even be a risk factor for MI, old MI, acute MI, and acute transmural MI of inferior wall.

Effects of Prior Metformin Use on Stroke Outcomes in Diabetes Patients with Acute Ischemic Stroke Receiving Endovascular Treatment

Diabetes mellitus (DM) predisposes individuals to vascular injury, leading to poor outcomes after ischemic stroke and symptomatic hemorrhagic transformation (SHT) after thrombolytic and endovascular treatment (EVT). Metformin (MET), an oral antidiabetic drug, has shown potential neuroprotective effects, but its impact on stroke prognosis in DM patients undergoing EVT remains unclear. In a multicenter study, 231 patients with DM undergoing EVT for acute ischemic stroke were enrolled. Prior MET use was identified, and patients were stratified into MET+ and MET- groups. Demographics, clinical data, and outcomes were compared between groups. Multivariate analysis was used to assess the effect of MET on stroke prognosis. Of the enrolled patients, 59.3% were previously on MET. MET+ patients had lower initial infarct volumes and NIHSS scores compared to MET-taking patients. Multivariate analysis showed that MET+ was associated with a lower risk of stroke progression and SHT (with stroke progression as follows: odd ratio [OR] 0.24, 95% confidence interval [CI] [0.12-0.48], p < 0.001; SHT: OR 0.33, 95% CI [0.14-0.75], p = 0.01) and was also associated with better 3-month functional outcomes (mRS 0-2) after EVT. Prestroke MET use in DM patients undergoing EVT is associated with improved stroke prognosis, including reduced risk of stroke progression and SHT and better functional outcomes. These findings suggest the potential neuroprotective role of MET in this population and highlight its clinical utility as an adjunctive therapy in the management of ischemic stroke. Further research is warranted to elucidate the underlying mechanisms and to optimize MET therapy in this setting.

Metformin adverse event profile: a pharmacovigilance study based on the FDA Adverse Event Reporting System (FAERS) from 2004 to 2022

BACKGROUND

Metformin has the potential for treating numerous diseases, but there are still many unrecognized and unreported adverse events (AEs).

METHODS

We selected data from the United States FDA Adverse Event Reporting System (FAERS) database from the first quarter (Q1) of 2004 to the fourth quarter (Q4) of 2022 for disproportionality analysis to assess the association between metformin and related adverse events.

RESULTS

In this study 10,500,295 case reports were collected from the FAERS database, of which 56,674 adverse events related to metformin were reported. A total of 643 preferred terms (PTs) and 27 system organ classes (SOCs) that were significant disproportionality conforming to the four algorithms simultaneously were included. The SOCs included metabolic and nutritional disorders (p = 0.00E + 00), gastrointestinal disorders (p = 0.00E + 00) and others. PT levels were screened for adverse drug reaction (ADR) signals such as acute pancreatitis (p = 0.00E + 00), melas syndrome, pemphigoid (p = 0.00E + 00), skin eruption (p = 0.00E + 00) and drug exposure during pregnancy (p = 0.00E + 00).

CONCLUSION

Most of our results were consistent with the specification, but some new signals of adverse reactions such as acute pancreatitis were not included. Therefore, further studies are needed to validate unlabeled adverse reactions and provide important support for clinical monitoring and risk identification of metformin.

Impact of Fixed Combination of Metformin and Pioglitazone on Insulin Resistance of Patients with Type 2 Diabetes: Results of a Randomized Open-Label Study

Aim

To compare the effect of metformin, a fixed combination of metformin and pioglitazone, or dapagliflozin on insulin resistance in patients with newly diagnosed type 2 diabetes.

Methods

In this 6-week randomized open-label trial, 58 patients were randomly assigned to insulin with metformin, a fixed combination of metformin and pioglitazone, or dapagliflozin for 4 weeks. Hyperinsulinemic euglycemic clamp tests and FreeStyle Libre Pro Sensor were used to evaluate the insulin sensitivity represented by glucose-infusion rate (M value) and glycemic control, respectively. The main outcome was changes in insulin resistance compared with baseline.

Results

The baseline characteristics were well matched among the three groups. When compared to baseline, insulin sensitivity after treatment was significantly improved. Further study revealed that the fixed combination of metformin and pioglitazone provided superior M-value improvement compared with metformin, but not different from dapagliflozin. Moreover, a greater reduction in insulin dose was observed in the fixed combination of metformin and pioglitazone group than the metformin or dapagliflozin group. However, there were no significant differences in the parameters of glycemic control within the groups.

Conclusion

In patients with newly diagnosed type 2 diabetes, a fixed combination of metformin and pioglitazone provided greater improvement in insulin resistance than metformin alone and similar changes in insulin resistance to dapagliflozin.

Metformin alleviates ethanol-induced cardiomyocyte injury by activating AKT/Nrf2 signaling in an ErbB2-dependent manner

BACKGROUND

Metformin, a first-line oral anti-diabetic drug, has recently been reported to exert protective effect on various cardiovascular diseases. However, the potential role of metformin in ethanol-induced cardiomyocyte injury is still unknown. Therefore, this study was aimed to investigate the effect of metformin on ethanol-induced cardiomyocyte injury and its underlying mechanism.

METHODS AND RESULTS

H9c2 cardiomyocytes were exposed to ethanol for 24 h to establish an ethanol-induced cardiomyocyte injury model, and followed by treatment with metformin in the presence or absence of Lapatinib (an ErbB2 inhibition). CCK8 and LDH assays demonstrated that metformin improved cell viability in cardiomyocytes exposed to ethanol. Furthermore, metformin suppressed cardiomyocyte apoptosis and reduced the expressions of apoptosis-related proteins (Bax and C-CAS-3). In addition, our results showed that metformin activated the AKT/Nrf2 pathway, and then promoted Nrf2 nuclear translocation and the transcription of its downstream antioxidant genes (HO-1, CAT and SOD2), thereby inhibiting oxidative stress. Interestingly, we found that ErbB2 protein expression was significantly inhibited in ethanol-treated cardiomyocytes, which was markedly reversed by metformin. In contrast, Lapatinib largely abrogated the activation of AKT/Nrf2 signaling by metformin, accompanied by the increases in oxidative stress and cardiomyocyte apoptosis, indicating that metformin prevented ethanol-induced cardiomyocyte injury in an ErbB2-dependent manner.

CONCLUSION

In summary, our study provides the first evidence that metformin protects cardiomyocyte against ethanol-induced oxidative stress and apoptosis by activating ErbB2-mediated AKT/Nrf2 signaling. Thus, metformin may be a potential novel treatment approach for alcoholic cardiomyopathy.

AMPK/mTOR-mediated therapeutic effect of metformin on myocardial ischaemia reperfusion injury in diabetic rat

BACKGROUND

The autophagy associated signalling pathways such as AMPK/mTOR previously were suggested to play a crucial role in protecting from ischaemia-reperfusion injury (IRI). The objective of this study was to evaluate the effect of metformin (DMBG) on autophagy during myocardial IRI with diabetes mellitus (DM).

METHODS

The DM rat model was established using streptozocin, and further induced ischaemia model via transitory ligation of the left anterior coronary artery and following reperfusion. The model rats were treated with 400 mg/kg/day DMBG for 1 week. Autophagosomes were investigated using transmission electron microscopy. Autophagy-associated signalling pathways were detected by western blot.

RESULTS

The myocardial infarct size was shown to significantly increase in the DM rats exposed to IRI compared to negative control, but decrease in DMBG treated. The mature autophagosomes were elevated in infarction and marginal zones of DM + IRI + DMBG compared to DM + IRI. Furthermore, the increasing protein levels of LC3-II, BECLIN 1, autophagy related 5 (ATG5) and AMP-activated protein kinase suggested activated autophagy-associated intracellular signalling AMPK and mTOR pathways upon DMBG treated.

CONCLUSIONS

Taken together, the outcomes determinate a novel mechanism that DMBG could activate autophagy process to provide a cardio-protective effect against DM induced myocardial IRI.

Effect of metformin on adverse outcomes in T2DM patients: Systemic review and meta-analysis of observational studies

Background

The cardiovascular protection effect of metformin on patients with type 2 diabetes mellitus (T2DM) remains inconclusive. This systemic review and meta-analysis were to estimate the effect of metformin on mortality and cardiovascular events among patients with T2DM.

Methods

A search of the Pubmed and EMBASE databases up to December 2021 was performed. Adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) were pooled by a random-effects model with an inverse variance method.

Results

A total of 39 studies involving 2473009 T2DM patients were adopted. Compared to non-metformin therapy, the use of metformin was not significantly associated with a reduced risk of major adverse cardiovascular event (MACE) (HR = 1.06, 95%CI 0.91–1.22; I² = 82%), hospitalization (HR = 0.85, 95%CI 0.64–1.13; I² = 98%), heart failure (HR = 0.86, 95%CI 0.60–1.25; I² = 99%), stroke (HR = 1.16, 95%CI 0.88–1.53; I² = 84%), and risk of AMI (HR = 0.88, 95%CI 0.69–1.14; I² = 88%) in T2DM patients. Metformin was also not associated with significantly lowered risk of MACE compared to dipeptidyl peptidase-4 inhibitor (DPP-4i) in T2DM patients (HR = 0.95, 95%CI 0.73–1.23; I² = 84%).

Conclusions

The effect of metformin on some cardiovascular outcomes was not significantly better than the non-metformin therapy or DPP-4i in T2DM patients based on observational studies.

Aberrant HSF1 signaling activation underlies metformin amelioration of myocardial infarction in mice

Myocardial infarction (MI) is a cardiovascular disease with high morbidity and mortality. Clinically, rehabilitation after massive MI often has a poor prognosis. Therefore, it is necessary to explore the therapeutic methods of myocardial protection after MI. As a first-line treatment for type 2 diabetes, metformin has been found to have a certain protective effect on myocardial tissue. However, its pharmacological mechanism remains unclear. In this study, we investigated key factors that reduced MI with metformin. Through in vivo, in vitro, and in silico analyses, we identified HSF1 as a key target for metformin. HSF1 could up-regulate the transcriptional level of AMPKα2 through transcriptional activation and stimulate the activity of the downstream AMPK/mTOR signaling pathway. Metformin stimulated cardiomyocytes to form stress granules (SGs), and knockdown of HSF1 reversed this process. Furthermore, HSF1 exhibited better in vitro affinity for metformin than AMPK, suggesting that HSF1 may be a more sensitive target for metformin.

Cardiovascular outcomes associated with treatment of type 2 diabetes in patients with ischaemic heart failure

AIM

The optimal strategy for diabetes control in patients with heart failure (HF) following myocardial infarction (MI) remains unknown. Metformin, a guideline-recommended therapy for patients with chronic HF and type 2 diabetes mellitus (T2DM), is associated with reduced mortality and HF hospitalizations. However, worse outcomes have been reported when used at the time of MI. We compared outcomes of patients with T2DM and HF of ischaemic aetiology according to antidiabetic treatment.

METHODS AND RESULTS

This study used linked data from primary care, hospital admissions, and death registries for 4.7 million inhabitants in England, as part of the CALIBER resource. The primary endpoint was a composite of cardiovascular mortality and HF hospitalization. The secondary endpoints were the individual components of the primary endpoint and all-cause mortality. To evaluate the effect of temporal changes in diabetes treatment, antidiabetic medication was included as time-dependent covariates in survival analyses. The study included 1172 patients with T2DM and prior MI and incident HF between 3 January 1998 and 26 February 2010. Five hundred and ninety-six patients had the primary outcome over median follow-up of 2.53 (IQR: 0.98-4.92) years. Adjusted analyses showed a reduced hazard of the composite endpoint for exposure to all antidiabetic medication with hazard ratios (HRs) of 0.50 [95% confidence interval (CI): 0.42-0.59], 0.66 (95% CI: 0.55-0.80), and 0.53 (95% CI: 0.43-0.65), respectively. A similar effect was seen for all-cause mortality [HRs of 0.43 (95% CI: 0.35-0.52), 0.57 (95% CI: 0.46-0.70), and 0.34 (95% CI: 0.27-0.43), respectively].

CONCLUSIONS

When considering changes in antidiabetic treatment over time, all drug classes were associated with reduced risk of cardiovascular mortality and HF hospitalization.

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 use is associated with low risk of case fatality and disability rates in first-ever stroke patients with type 2 diabetes

Background:

To assess the effectiveness of metformin treatment on long-term outcomes in first-ever stroke patients with type 2 diabetes mellitus (T2DM) in China.

Methods:

From August to September 2019, all patients with first-ever stroke and T2DM from 232 hospitals in China Mainland were included. The enrolled patients were divided into two groups: the metformin treatment (MT) and the no-metformin treatment (No-MT) groups. All discharged patients would receive a telephone follow-up at 12-month after admission.

Results:

In total, 7587 first-ever stroke patients with T2DM [age: median (IQR) = 66 (57–73) years; 57.35% male] were recruited. Out of those 7587 included patients, 3593 (47.36%) received MT. The in-hospital case fatality rate was lower in the MT group than the No-MT group [MT group versus No-MT group: 1.09% versus 2.30%; absolute difference = −1.75% (95% CI = −2.15 to −1.17%); OR = 0.63 (95% CI = 0.47 to 0.84)]. The 12-month case fatality rate was lower in the MT group than the No-MT group [4.72% versus 8.05%; absolute difference = −4.05% (95% CI = −5.58 to −2.41); OR = 0.69 (95% CI = 0.50 to 0.88)]. The 12-month disability rate was also lower in the MT group than the No-MT group [14.74% versus 19.41%; absolute difference = −5.70% (95% CI = −7.25 to −3.22); OR = 0.83 (95% CI = 0.70 to 0.95)]. Furthermore, the recurrence rate did not differ significantly between the MT and No-MT groups (p = 0.29).

Conclusion:

The study reveals that metformin use in stroke patients with T2DM results in a less severe stroke and lower fatality and disability rates.

Myocardiocyte autophagy in the context of myocardiocytes regeneration: a potential novel therapeutic strategy

Background

The regeneration strategy involves several aspects, such as reprogramming aspects, targeting pathophysiological processes, and inducing the physiological one. Autophagy targeting is a potential physiological/pathogenetic strategy to enhance myocardiocytes' function. Myocardiocytes' injury-related death remains to be the highest in our era. Unfortunately, myocardiocytes have a limited proliferation capacity to compensate for what was lost by infarction. However, partially injured myocardiocytes can be preserved by improving the autophagy process of myocardiocytes.

Main text

Autophagy induction involved controlling the cellular and subcellular environment as well as gene expression. Autophagy is well known to prolong the longevity of cell and human life. Inhibition of the mTOR receptor, proapoptotic gene Bnip3, IP3, and lysosome inhibitors, inhibition of microRNA-22 and overexpression of microRNA-99a, modulators of activated protein kinase with adenosine monophosphate, resveratrol, sirtuin activators, Longevinex and calcium lowering agents can promote physiological myocardiocyte autophagy and improve post-myocardial modulation and recovery speed. The paper aimed to assess autophagy role in myocardiocytes regeneration modulation.

Conclusions

The autophagy strategy can be applied to infarcted myocardiocytes, as well as heart failure. However, cell self-eating is not the preferred therapy for preserving injured myocardiocytes or causing regeneration.

Association of Metformin with the Mortality and Incidence of Cardiovascular Events in Patients with Pre-existing Cardiovascular Diseases

INTRODUCTION

Whether metformin reduces all-cause cardiovascular mortality and the incidence of cardiovascular events in patients with pre-existing cardiovascular diseases (CVD) remains inconclusive. Some randomised controlled trials (RCTs) and cohort studies have shown that metformin is associated with an increased risk of mortality and cardiovascular events.

METHODS

We conducted a pooling synthesis to assess the effects of metformin in all-cause cardiovascular mortality and incidence of cardiovascular events in patients with CVD. Studies published up to October 2021 in PubMed or Embase with a registration in PROSPERO (CRD42020189905) were collected. Both RCT and cohort studies were included. Hazard ratios (HR) with 95% CI were pooled across various trials using the random-effects model.

RESULTS

This study enrolled 35 published studies (in 14 publications) for qualitative synthesis and identified 33 studies (published in 26 publications) for quantitative analysis. We analysed a total of 61,704 patients, among them 58,271 patients were used to calculate all-cause mortality while 12,814 patients were used to calculate cardiovascular mortality. Compared with non-metformin control, metformin usage is associated with a reduction in all-cause mortality (HR: 0.90; 95% CI 0.83, 0.98; p = 0.01), cardiovascular mortality (HR: 0.89; 95% CI 0.85, 0.94; p < 0.0001), incidence of coronary revascularisation (HR: 0.79; 95% CI 0.64, 0.98; p = 0.03), and heart failure (HR: 0.90; 95% CI 0.87, 0.94; p < 0.0001) in patients with pre-existing cardiovascular diseases.

CONCLUSION

Metformin use is associated with a reduction in all-cause mortality, cardiovascular mortality, incidence of coronary revascularisation, and heart failure in patients with CVD; however, metformin usage was not associated with reduction in the incidence of myocardial infarction, angina, or stroke.

The effect of concomitant chronic kidney disease on the recurrence of atrial fibrillation after catheter ablation: A protocol for systematic review and meta-analysis

BACKGROUND

Some new trials have reported the effectiveness of chronic kidney disease on recurrence of atrial fibrillation following catheter ablation. Limited by small number of studies and insufficient outcomes, previous meta-analyses also failed to draw a consistent conclusion on this topic. We thus conducted a new meta-analysis to systematically analyze the effect of chronic kidney disease on recurrence of atrial fibrillation following catheter ablation.

METHODS

Two independent investigators followed The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) reporting guidelines to conduct the present meta-analysis. From the inception to June 2021, the EMBASE, PubMed, Web of Science, and Cochrane Library electronic databases were searched using the key phrases "atrial fibrillation," "chronic kidney disease," "catheter ablation," "renal failure," "renal function," "renal insufficiency," "end-stage renal disease," and "dialysis" for all relevant English-language trials. Observational or randomized controlled trial focusing on assessing the effectiveness of chronic kidney disease on recurrence of atrial fibrillation following catheter ablation was included. P < .05 was set as the significance level.

RESULTS

Our hypothesis was that chronic kidney disease is associated with increased atrial fibrosis and a higher risk of arrhythmia recurrence and that restoration of normal rhythm through catheter ablation is associated with improved kidney function.

REGISTRATION NUMBER

10.17605/OSF.IO/3WJAE.

Effects of continuous use of metformin on cardiovascular outcomes in patients with type 2 diabetes after acute myocardial infarction: A protocol for systematic review and meta-analysis

BACKGROUND

To our knowledge, no meta-analyses or reviews have investigated the efficacy and safety of metformin on cardiovascular outcomes after acute myocardial infarction (AMI) in patients with type 2 diabetes mellitus (T2DM). We thus conduct a high-quality systematic review and meta-analysis to assess the efficacy and safety of metformin on cardiovascular outcomes after AMI in patients with T2DM.

METHODS

In this systematic review and meta-analysis, we will search PUBMED, Scopus, EMBASE, and Cochrane Library databases through April, 2021. The study is structured to adhere to PRISMA guidelines (i.e., Preferred Reporting Items for Systematic Reviews and Meta-analyses). The literature search, data extraction, and quality assessments are conducted independently by 2 authors. Outcome measures include all-cause mortality; complications such as acute kidney injury, lactic acidosis, hospitalization for AMI or stroke, or death. Where disagreement in the collection of data occurs, this is resolved through discussion. Review Manager Software (v 5.3; Cochrane Collaboration) is used for the meta-analysis. Two independent reviewers will assess the risk of bias of the included studies at study level.

RESULTS

It is hypothesized that metformin use at the post-AMI is associated with decreased risk of cardiovascular disease and death in patients with T2DM.

CONCLUSIONS

This study expects to provide credible and scientific evidence for the efficacy and safety of metformin on cardiovascular outcomes after AMI in patients with T2DM.

REGISTRATION NUMBER

10.17605/OSF.IO/S3MBP.

Concurrent diabetes and heart failure: interplay and novel therapeutic approaches

Diabetes mellitus increases the risk of developing heart failure, and the co-existence of both diseases worsens cardiovascular outcomes, hospitalization and the progression of heart failure. Despite current advancements on therapeutic strategies to manage hyperglycemia, the likelihood of developing diabetes-induced heart failure is still significant, especially with the accelerating global prevalence of diabetes and an ageing population. This raises the likelihood of other contributing mechanisms beyond hyperglycemia in predisposing diabetic patients to cardiovascular disease risk. There has been considerable interest in understanding the alterations in cardiac structure and function in the diabetic patients, collectively termed as "diabetic cardiomyopathy". However, the factors that contribute to the development of diabetic cardiomyopathies is not fully understood. This review summarizes the main characteristics of diabetic cardiomyopathies, and the basic mechanisms that contribute to its occurrence. This includes perturbations in insulin resistance, fuel preference, reactive oxygen species generation, inflammation, cell death pathways, neurohormonal mechanisms, advanced glycated end-products accumulation, lipotoxicity, glucotoxicity, and posttranslational modifications in the heart of the diabetic. This review also discusses the impact of antihyperglycemic therapies on the development of heart failure, as well as how current heart failure therapies influence glycemic control in diabetic patients. We also highlight the current knowledge gaps in understanding how diabetes induces heart failure.

Clinical profiles and quality of care of subjects with type 2 diabetes according to their cardiovascular risk: an observational, retrospective study

Background

The European Society of Cardiology (ESC) recently defined cardiovascular risk classes for subjects with diabetes. Aim of this study was to explore the distribution of subjects with type 2 diabetes (T2D) by cardiovascular risk groups according to the ESC classification and to describe the quality indicators of care, with particular regard to cardiovascular risk factors.

Methods

The study is based on data extracted from electronic medical records of patients treated at the 258 Italian diabetes centers participating in the AMD Annals initiative. Patients with T2D were stratified by cardiovascular risk. General descriptive indicators, measures of intermediate outcomes, intensity/appropriateness of pharmacological treatment for diabetes and cardiovascular risk factors, presence of other complications and overall quality of care were evaluated.

Results

Overall, 473,740 subjects with type 2 diabetes (78.5% at very high cardiovascular risk, 20.9% at high risk and 0.6% at moderate risk) were evaluated. Among people with T2D at very high risk: 26.4% had retinopathy, 39.5% had albuminuria, 18.7% had a previous major cardiovascular event, 39.0% had organ damage, 89.1% had three or more risk factors. The use of DPP4-i markedly increased as cardiovascular risk increased. The prescription of secretagogues also increased and that of GLP1-RAs tended to increase. The use of SGLT2-i was still limited, and only slightly higher in subjects with very high cardiovascular risk. The overall quality of care, as summarized by the Q score, tended to be lower as the level of cardiovascular risk increased.

Conclusions

A large proportion of subjects with T2D is at high or very high risk. Glucose-lowering drug therapies seem not to be adequately used with respect to their potential advantages in terms of cardiovascular risk reduction. Several actions are necessary to improve the quality of care.

SGLT2 inhibitors and GLP1 agonists administered without metformin compared to other glucose-lowering drugs in patients with type 2 diabetes mellitus to prevent cardiovascular events: A systematic review

OBJECTIVES

To assess the efficacy of glucagon-like peptide-1 receptor agonists (GLP1-RAs) and sodium-glucose co-transporter 2 (SGLT2) inhibitors, administered without metformin on cardiovascular outcomes in type 2 diabetes patients.

METHODS

A systematic review was performed according to Cochrane's methodological standards. We included randomized clinical trials (RCTs) on adult type 2 diabetes patients, assessing the efficacy of SGLT2 inhibitors and GLP1-RAs compared to other glucose-lowering drugs and/or RCTs that presented data of a subgroup of type 2 diabetes patients without metformin use at baseline. The main outcome was the reduction of the risk of any major adverse cardiovascular events (MACE) reported individually or as a composite outcome.

RESULTS

Five RCTs including 50,725 type 2 diabetes patients, of whom 10,013 had not received metformin, were included in this meta-analysis. Three of these studies assessed the efficacy of GLP1-RAs and two of SGLT2 inhibitors. In patients without metformin at baseline, GLP1-RAs in comparison with placebo reduced the risk of MACE significantly by 20% (HR: 0.80; 95% CI: 0.71-0.89). SGLT2 inhibitors also significantly reduced the risk of MACE by 32% (HR: 0.68; 95% CI: 0.57-0.81).

CONCLUSIONS

SGLT2 inhibitors and GLP1-RAs provided without metformin at baseline may reduce the risk of MACE in comparison with placebo in type 2 diabetes patients at increased risk of cardiovascular events.

Association of metformin monotherapy or combined therapy with cardiovascular risks in patients with type 2 diabetes mellitus

Background

Metformin is a first-line drug in type 2 diabetes mellitus (T2DM) treatment, yet whether metformin may increase all-cause or cardiovascular mortality of T2DM patients remains inconclusive.

Methods

We searched PubMed and Embase for data extracted from inception to July 14, 2020, with a registration in PROSPERO (CRD42020177283). This study included randomized controlled trials (RCT) assessing the cardiovascular effects of metformin for T2DM. This study is followed by PRISMA and Cochrane guideline. Risk ratio (RR) with 95% CI was pooled across trials by a random-effects model. Primary outcomes include all-cause mortality and cardiovascular mortality.

Results

We identified 29 studies that randomly assigned patients with 371 all-cause and 227 cardiovascular death events. Compared with untreated T2DM patients, metformin-treated patients was not associated with lower risk of all-cause mortality (RR: 0.98; 95%CI: 0.69–1.38; P = 0.90), cardiovascular mortality (RR: 1.13; 95% CI: 0.60, 2.15; P = 0.70), macrovascular events (RR: 0.87; 95%CI: 0.70–1.07; P = 0.19), heart failure (RR: 1.02; 95% CI:0.61–1.71; P = 0.95), and microvascular events (RR: 0.78; 95% CI:0.54–1.13; P = 0.19). Combination of metformin with another hypoglycemic drug was associated with higher risk of all-cause mortality (RR: 1.49; 95% CI: 1.02, 2.16) and cardiovascular mortality (RR: 2.21; 95% CI: 1.22, 4.00) compared with hypoglycemic drug regimens with no metformin.

Conclusion

The combination of metformin treatment may impose higher risk in all-cause and cardiovascular mortality. This finding, at least in part, shows no evidence for benefits of metformin in combination in terms of all-cause/cardiovascular mortality and cardiovascular events for T2DM. However, the conclusion shall be explained cautiously considering the limitations from UK Prospective Diabetes Study (UKPDS).

Heart Failure in Diabetes Mellitus: An Updated Review

Diabetes mellitus (DM) and heart failure (HF) are comorbid conditions associated with significant morbidity and mortality worldwide. Despite the availability of novel and effective therapeutic options and intensive glycaemic control strategies, mortality and hospitalisation rates continue to remain high and the incidence of HF persists. In this review, we described the impact of currently available glucose-lowering therapies in DM with a focus on HF clinical outcomes. Non-conventional modes of management and alternative pathophysiological mechanisms with the potential for therapeutic targeting are also discussed.

Metformin treatment in heart failure with preserved ejection fraction: a systematic review and meta-regression analysis

Background

Observational series suggest a mortality benefit from metformin in the heart failure (HF) population. However, the benefit of metformin in HF with preserved ejection fraction (HFpEF) has yet to be explored. We performed a systematic review and meta-analysis to identify whether variation in EF impacts mortality outcomes in HF patients treated with metformin.

Methods

MEDLINE and EMBASE were searched up to October 2019. Observational studies and randomised trials reporting mortality in HF patients and the proportion of patients with an EF > 50% at baseline were included. Other baseline variables were used to assess for heterogeneity in treatment outcomes between groups. Regression models were used to determine the interaction between metformin and subgroups on mortality.

Results

Four studies reported the proportion of patients with a preserved EF and were analysed. Metformin reduced mortality in both preserved or reduced EF after adjustment with HF therapies such as angiotensin converting enzyme inhibitors (ACEi) and beta-blockers (β = − 0.2 [95% CI − 0.3 to − 0.1], p = 0.02). Significantly greater protective effects were seen with EF > 50% (p = 0.003). Metformin treatment with insulin, ACEi and beta-blocker therapy were also shown to have a reduction in mortality (insulin p = 0.002; ACEi p < 0.001; beta-blocker p = 0.017), whereas female gender was associated with worse outcomes (p < 0.001).

Conclusions

Metformin treatment is associated with a reduction in mortality in patients with HFpEF.

Metformin protects against ischaemic myocardial injury by alleviating autophagy-ROS-NLRP3-mediated inflammatory response in macrophages

Myocardial ischaemia is usually accompanied by inflammatory response which plays a critical role in the myocardial healing and scar formation, while persistent inflammatory response contributes greatly to the myocardial remodeling and consequent heart failure. Metformin (Met), a widely used hypoglycemic drug, has increasingly been shown to exert remarkable cardioprotective effect on ischaemic myocardial injury such as acute myocardial infarction (AMI). However, the underlying mechanisms are still far from being fully understood. In this study, a mouse model of AMI was established through ligating the left anterior descending coronary artery (LAD), 100 mg/kg Met was given immediately after operation once daily for 3 days. It was demonstrated that Met effectively improved the cardiac haemodynamics (LVSP, LVEDP, +dp/dt, -dp/dt), diminished the infarct size, alleviated the disarrangement of myocardial cells and reduced the infiltration of inflammatory cells (macrophages, neutrophils and lymphocytes) in the heart of AMI mice. Mechanistically, Met decreased the expression of NLRP3 and enhanced the accumulation of LC3 puncta in F4/80-positive macrophages in the heart of AMI mice. Single cell suspension of cardiac macrophages was prepared from AMI mice and exhibited increased NLRP3 mRNA and protein expression. In contrast, Met decreased the expression of NLRP3 and p62, whereas increased the ratio of LC3II/LC3I. Additionally, both conditioned medium from H9c2 cardiomyocytes exposed to hydrogen peroxide (H9c2-H₂O₂-CM) and combination of mtDNA and ATP (mtDNA-ATP) increased the expression of NLRP3 and cleaved caspase-1 (p10) as well as intracellular ROS production in RAW264.7 macrophages, which were abrogated by Met treatment. Strikingly, chloroquine (CQ), 3-methyladenine (3-MA) and knockdown of autophagy-related gene (Atg5) abrogated the inhibitory effects of Met on H9c2-H₂O₂-CM and mtDNA-ATP-induced NLRP3 expression, release of IL-1β and IL-18 as well as ROS production in RAW264.7 macrophages. Collectively, these findings suggest that Met protects against ischaemic myocardial injury through alleviating autophagy-ROS-NLRP3 axis-mediated inflammatory response in macrophages.

Autophagy-dependent and -independent modulation of oxidative and organellar stress in the diabetic heart by glucose-lowering drugs

Autophagy is a lysosome-dependent intracellular degradative pathway, which mediates the cellular adaptation to nutrient and oxygen depletion as well as to oxidative and endoplasmic reticulum stress. The molecular mechanisms that stimulate autophagy include the activation of energy deprivation sensors, sirtuin-1 (SIRT1) and adenosine monophosphate-activated protein kinase (AMPK). These enzymes not only promote organellar integrity directly, but they also enhance autophagic flux, which leads to the removal of dysfunctional mitochondria and peroxisomes. Type 2 diabetes is characterized by suppression of SIRT1 and AMPK signaling as well as an impairment of autophagy; these derangements contribute to an increase in oxidative stress and the development of cardiomyopathy. Antihyperglycemic drugs that signal through insulin may further suppress autophagy and worsen heart failure. In contrast, metformin and SGLT2 inhibitors activate SIRT1 and/or AMPK and promote autophagic flux to varying degrees in cardiomyocytes, which may explain their benefits in experimental cardiomyopathy. However, metformin and SGLT2 inhibitors differ meaningfully in the molecular mechanisms that underlie their effects on the heart. Whereas metformin primarily acts as an agonist of AMPK, SGLT2 inhibitors induce a fasting-like state that is accompanied by ketogenesis, a biomarker of enhanced SIRT1 signaling. Preferential SIRT1 activation may also explain the ability of SGLT2 inhibitors to stimulate erythropoiesis and reduce uric acid (a biomarker of oxidative stress)—effects that are not seen with metformin. Changes in both hematocrit and serum urate are the most important predictors of the ability of SGLT2 inhibitors to reduce the risk of cardiovascular death and hospitalization for heart failure in large-scale trials. Metformin and SGLT2 inhibitors may also differ in their ability to mitigate diabetes-related increases in intracellular sodium concentration and its adverse effects on mitochondrial functional integrity. Differences in the actions of SGLT2 inhibitors and metformin may reflect the distinctive molecular pathways that explain differences in the cardioprotective effects of these drugs.