Metformin use and cardiovascular events in patients with type 2 diabetes and chronic kidney disease

Potentials of Natural Antioxidants in Reducing Inflammation and Oxidative Stress in Chronic Kidney Disease

Chronic kidney disease (CKD) presents a substantial global public health challenge, with high morbidity and mortality. CKD patients often experience dyslipidaemia and poor glycaemic control, further exacerbating inflammation and oxidative stress in the kidney. If left untreated, these metabolic symptoms can progress to end-stage renal disease, necessitating long-term dialysis or kidney transplantation. Alleviating inflammation responses has become the standard approach in CKD management. Medications such as statins, metformin, and GLP-1 agonists, initially developed for treating metabolic dysregulation, demonstrate promising renal therapeutic benefits. The rising popularity of herbal remedies and supplements, perceived as natural antioxidants, has spurred investigations into their potential efficacy. Notably, lactoferrin, Boerhaavia diffusa, Amauroderma rugosum, and Ganoderma lucidum are known for their anti-inflammatory and antioxidant properties and may support kidney function preservation. However, the mechanisms underlying the effectiveness of Western medications and herbal remedies in alleviating inflammation and oxidative stress occurring in renal dysfunction are not completely known. This review aims to provide a comprehensive overview of CKD treatment strategies and renal function preservation and critically discusses the existing literature's limitations whilst offering insight into the potential antioxidant effects of these interventions. This could provide a useful guide for future clinical trials and facilitate the development of effective treatment strategies for kidney functions.

Clinical outcomes following discontinuation of metformin in patients with type 2 diabetes and advanced chronic kidney disease in Hong Kong: a territory-wide, retrospective cohort and target trial emulation study

Background

Current labelling advises discontinuation of metformin when estimated glomerular filtration rate (eGFR) < 30 ml/min/1.73 m2 due to increased risk of lactic acidosis. However, in real-world practice, the risk-benefit ratios remain uncertain. We examined the risk associations of discontinued-metformin use with cardiorenal and clinical outcomes in patients with type 2 diabetes (T2D) and advanced chronic kidney disease.

Methods

In this territory-wide, retrospective cohort and target trial emulation study, we included Chinese patients attending the Hong Kong Hospital Authority (HA) and enrolled in the Risk-Assessment-and-Management-Programme-for-Diabetes-Mellitus (RAMP-DM) from 2002 to 2019. Patients were stratified by discontinuation of metformin within six months after reaching eGFR < 30 ml/min/1.73 m2 from January 1, 2002 to December 31, 2018, and followed up until December 31 2019. We excluded patients who had observational time <6 months from eGFR < 30 ml/min/1.73 m2, and had their eGFR measured during a hospitalisation episode due to acute kidney injury, or missing diagnosis date of diabetes. We compared the risk associations of metformin discontinuation with clinical outcomes. The primary outcomes were major adverse cardiovascular events (MACE), end-stage kidney disease (ESKD), cancer, and all-cause mortality. A Cox-model with time-dependent exposure and covariates was used to estimate the hazard ratio (HR) of outcomes in a propensity-score overlap-weighted cohort. The risk of occurrence of lactic acidosis (serum lactate > 5.0 mmol/L with a concomitant blood pH < 7.35 or ICD-9 codes of 276.2) in discontinued-metformin versus continued-metformin users was assessed in a separate register-based cohort.

Findings

A total of 33,586 metformin users with new-onset eGFR < 30 ml/min/1.73 m2 were included in the study, 7500 (22.3%) of whom discontinued metformin within 6 months whereas 26,086 (77.7%) continued use of metformin. During a median follow-up of 3.8 (IQR: 2.2-6.1) years, 16.4% (5505/33,586), 30.1% (10,113/33,586), and 7.1% (2171/30,682) had incident MACE, ESKD, and cancer respectively, and 44.4% (14,917/33,586) died. Compared to continued-metformin use, discontinuation was associated with higher risk of MACE (weighted and adjusted HR = 1.40, 95% CI: 1.29-1.52), ESKD (HR = 1.52, 1.42-1.62), and death (HR = 1.22, 1.18-1.27). No association was observed for cancer (HR = 0.93, 0.85-1.01). Discontinued-metformin users had higher change in HbA1c change at 6-month of follow-up versus continued-metformin users (weighted mean HbA1c level change: 0.5% [0.4-0.6%] versus 0.2% [0.1-0.2]). In the separate register-based cohort (n = 3235), null association was observed between metformin use and risk of lactic acidosis (weighted HR = 0.94 [0.53-1.64]).

Interpretation

Our results suggest that discontinuation of metformin in patients with T2D and chronic kidney disease may be associated with increased risk of cardiovascular-renal events. Use of metformin below eGFR of 30 ml/min/1.73 m2 may be associated with cardiovascular, renal, and mortality benefits that need to be weighed against the risk of lactic acidosis, but further research is needed to validate these findings.

Funding

CUHK Impact Research Fellowship Scheme.

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.

Impact of metformin on cardiovascular and kidney outcome based on kidney function status in type 2 diabetic patients: a multicentric, retrospective cohort study

Metformin is the primary treatment for type 2 diabetes mellitus (T2DM) due to its effectiveness in improving clinical outcomes in patients with preserved renal function, however, the evidence on the effectiveness of metformin in various renal functions is lacking. We performed a retrospective, multicenter, observational study used data of patients with T2DM obtained from three tertiary hospitals' databases. Patients given metformin within run-in periods and with at least one additional prescription formed the metformin cohort. A control cohort comprised those prescribed oral hypoglycemic agents other than metformin and never subsequently received a metformin prescription within observation period. For patients without diabetic nephropathy (DN), the outcomes included events of DN, major adverse cardiovascular events (MACE), and major adverse kidney events (MAKE). After 1:1 propensity matching, 1994 individuals each were selected for the metformin and control cohorts among T2DM patients without baseline DN. The incidence rate ratios (IRR) for DN, MACEs, and MAKEs between cohorts were 1.06 (95% CI 0.96-1.17), 0.76 (0.64-0.92), and 0.45 (0.33-0.62), respectively. In cohorts with renal function of CKD 3A, 3B, and 4, summarized IRRs of MACEs and MAKEs were 0.70 (0.57-0.87) and 0.39 (0.35-0.43) in CKD 3A, 0.83 (0.74-0.93) and 0.44 (0.40-0.48) in CKD 3B, and 0.71 (0.60-0.85) and 0.45 (0.39-0.51) in CKD 4. Our research indicates that metformin use in T2DM patients across various renal functions consistently correlates with a decreased risk of overt DN, MACE, and MAKE.

Targeting mitochondrial quality control for diabetic cardiomyopathy: Therapeutic potential of hypoglycemic drugs

Diabetic cardiomyopathy is a chronic cardiovascular complication caused by diabetes that is characterized by changes in myocardial structure and function, ultimately leading to heart failure and even death. Mitochondria serve as the provider of energy to cardiomyocytes, and mitochondrial dysfunction plays a central role in the development of diabetic cardiomyopathy. In response to a series of pathological changes caused by mitochondrial dysfunction, the mitochondrial quality control system is activated. The mitochondrial quality control system (including mitochondrial biogenesis, fusion and fission, and mitophagy) is core to maintaining the normal structure of mitochondria and performing their normal physiological functions. However, mitochondrial quality control is abnormal in diabetic cardiomyopathy, resulting in insufficient mitochondrial fusion and excessive fission within the cardiomyocyte, and fragmented mitochondria are not phagocytosed in a timely manner, accumulating within the cardiomyocyte resulting in cardiomyocyte injury. Currently, there is no specific therapy or prevention for diabetic cardiomyopathy, and glycemic control remains the mainstay. In this review, we first elucidate the pathogenesis of diabetic cardiomyopathy and explore the link between pathological mitochondrial quality control and the development of diabetic cardiomyopathy. Then, we summarize how clinically used hypoglycemic agents (including sodium-glucose cotransport protein 2 inhibitions, glucagon-like peptide-1 receptor agonists, dipeptidyl peptidase-4 inhibitors, thiazolidinediones, metformin, and α-glucosidase inhibitors) exert cardioprotective effects to treat and prevent diabetic cardiomyopathy by targeting the mitochondrial quality control system. In addition, the mechanisms of complementary alternative therapies, such as active ingredients of traditional Chinese medicine, exercise, and lifestyle, targeting mitochondrial quality control for the treatment of diabetic cardiomyopathy are also added, which lays the foundation for the excavation of new diabetic cardioprotective drugs.

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.

Effects of Metformin on Ischemia/Reperfusion Injury: New Evidence and Mechanisms

The search for new drugs with the potential to ensure therapeutic success in the treatment of cardiovascular diseases has become an essential pathway to follow for health organizations and committees around the world. In June 2021, the World Health Organization listed cardiovascular diseases as one of the main causes of death worldwide, representing 32% of them. The most common is coronary artery disease, which causes the death of cardiomyocytes, the cells responsible for cardiac contractility, through ischemia and subsequent reperfusion, which leads to heart failure in the medium and short term. Metformin is one of the most-used drugs for the control of diabetes, which has shown effects beyond the control of hyperglycemia. Some of these effects are mediated by the regulation of cellular energy metabolism, inhibiting apoptosis, reduction of cell death through regulation of autophagy and reduction of mitochondrial dysfunction with further reduction of oxidative stress. This suggests that metformin may attenuate left ventricular dysfunction induced by myocardial ischemia; preclinical and clinical trials have shown promising results, particularly in the setting of acute myocardial infarction. This is a review of the molecular and pharmacological mechanisms of the cardioprotective effects of metformin during myocardial ischemia-reperfusion injury.

Metformin use is associated with reduced acute kidney injury following coronary artery bypass grafting in patients with type 2 diabetes: An inverse probability of treatment weighting analysis

STUDY OBJECTIVE

Acute kidney injury (AKI) is a common and serious complication after coronary artery bypass grafting (CABG) surgery. Patients with diabetes are commonly associated with renal microvascular complications and have a greater risk of AKI after CABG surgery. This study aimed to explore whether preoperative metformin administration could reduce the incidence of postoperative AKI following CABG in patients with type 2 diabetes.

DESIGN

Patients with diabetes who underwent CABG were retrospectively included in this study. AKI after CABG was defined according to the Kidney Disease Improving Global Outcomes (KDIGO) criteria. The effects of metformin on postoperative AKI following CABG in patients were compared and analyzed.

DATA SOURCE

Patients were enrolled in this study between January 2019 and December 2020 in Beijing Anzhen Hospital.

PATIENTS

A total of 812 patients were enrolled. The patients were divided into the metformin group (203 cases) and the control group (609 cases) according to whether metformin was used preoperatively.

INTERVENTION

Inverse probability of treatment weighting (IPTW) was applied to minimize baseline differences between the two groups. IPT-weighted p values were analyzed to evaluate the postoperative outcomes between the two groups.

MEASUREMENTS AND MAIN RESULTS

The incidence of AKI in the metformin group and the control group was compared. After IPTW adjustment, the incidence of AKI in the metformin group was lower than the control group (IPTW-adjusted p < 0.001). In the subgroup analysis, metformin showed significant protective effects in the estimated glomerular filtration rate (eGFR) < 60 mL/min per 1.73 m2 and eGFR 60-90 mL/min per 1.73 m2 subgroups, which was not observed in the eGFR ≥90 mL/min per 1.73 m2 subgroup. No significant differences in the incidence of renal replacement therapy, reoperation due to bleeding, in-hospital mortality, or red blood cell transfusion volume were observed between the two groups.

CONCLUSIONS

In this study, we provided evidence that preoperative metformin was associated with a significant reduction of postoperative AKI following CABG in patients with diabetes. Metformin showed significant protective effects in patients with mild-to-moderate renal insufficiency.

Frequency and predictors of inappropriate medication dosages for cardiovascular disease prevention in chronic kidney disease patients: A retrospective cross-sectional study in a Malaysian primary care clinic

Patients with chronic kidney disease (CKD) are at increased risk of cardiovascular events. This study aimed to assess the frequency of inappropriate medication dosages (IMD) for cardiovascular disease prevention among patients with CKD and its predictors in an urban academic primary care clinic in Selangor, Malaysia. All patients who attended the clinic from April to June 2019 and fulfilled the inclusion criteria were included in this cross-sectional study, except for those with an estimated glomerular filtration rate (eGFR) of more than 90 ml/min, diagnosed with urinary tract infection, pregnant or were on dialysis for end stage renal disease. Their prescriptions on the electronic medical record (EMR) system were evaluated for appropriateness using the dose adjustment recommendations based on the 2018 Malaysian Clinical Practice Guidelines on management of CKD. A total of 362 medical records were included in this study. 16.6% (95% Confidence Interval [CI]: 12.9-20.8) or 60 out of 362 of the patient records analysed contained medications prescribed with inappropriate dosages. Patients with higher stages of CKD were associated with higher odds of IMD, namely CKD stage G3b (adjusted Odds Ratio [aOR] 10.41; 95% CI: 2.31-46.88) and CKD stage 4-5 (aOR 15.76; 95% CI: 3.22-77.28). Other predictors of IMD were diagnosis of diabetes mellitus (aOR 6.40; 95% CI: 2.15-19.01), number of prescribed medications of 5 or more (aOR 4.69; 95% CI: 1.55-14.20), and eGFR reduction of more than 25% over one year (aOR 2.82; 95% CI: 1.41-5.65). Within the limitations of this study, we conclude that the occurrence of IMD for CVD prevention was low in CKD patients in this primary care clinic. Medications with inappropriate dosages identified in this study include simvastatin, fenofibrate, hydrochlorothiazide, spironolactone, metformin, gliclazide, sitagliptin, dapagliflozin and empagliflozin. Clinicians should consider the predictors of inappropriate medication dosages listed above when prescribing to patients with CKD to reduce the risk of medications-related toxicities and adverse effects. Limitations of this study should be considered when interpreting the findings presented.

Erythropoiesis-stimulating agents for anaemia in adults with chronic kidney disease: a network meta-analysis

BACKGROUND

Erythropoiesis-stimulating agents (ESAs) are commonly used to treat anaemia in people with chronic kidney disease (CKD). However, their use has been associated with cardiovascular events. This is an update of a Cochrane review first published in 2014.

OBJECTIVES

To compare the efficacy and safety of ESAs (epoetin alfa, epoetin beta, darbepoetin alfa, methoxy polyethylene glycol-epoetin beta, and biosimilar ESAs against each other, placebo, or no treatment) to treat anaemia in adults with CKD.

SEARCH METHODS

In this update, we searched the Cochrane Kidney and Transplant Register of Studies up to 29 April 2022 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

Randomised controlled trials (RCTs) that included a comparison of an ESA (epoetin alfa, epoetin beta, darbepoetin alfa, methoxy polyethylene glycol-epoetin beta, a biosimilar epoetin or a biosimilar darbepoetin alfa) with another ESA, placebo or no treatment in adults with CKD were considered for inclusion.

DATA COLLECTION AND ANALYSIS

Two independent authors screened the search results and extracted data. Data synthesis was performed using random-effects pairwise meta-analysis (expressed as odds ratios (OR) and their 95% confidence intervals (CI)) and network meta-analysis. We assessed for heterogeneity and inconsistency within meta-analyses using standard techniques and planned subgroup and meta-regression to explore sources of heterogeneity or inconsistency. We assessed certainty in treatment estimates for the primary outcomes (preventing blood transfusions and death (any cause)) using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

MAIN RESULTS

Sixty-two new studies (9237 participants) were included in this update, so the review now includes 117 studies with 25,237 participants. Most studies were at high or unclear risk of bias in most methodological domains. Overall, results remain similar in this update compared to our previous review in 2014. For preventing blood transfusion, epoetin alfa (OR 0.28, 95% CI 0.13 to 0.61; low certainty evidence) and epoetin beta (OR 0.19, 95% CI 0.08 to 0.47; low certainty evidence) may be superior to placebo, and darbepoetin alfa was probably superior to placebo (OR 0.27, 95% CI 0.11 to 0.67; moderate certainty evidence). Methoxy polyethylene glycol-epoetin beta (OR 0.33, 95% CI 0.11 to 1.02; very low certainty evidence), a biosimilar epoetin (OR 0.34, 95% CI 0.11 to 1.03; very low certainty evidence) and a biosimilar darbepoetin alfa (OR 0.37, 95% CI 0.07 to 1.91; very low certainty evidence) had uncertain effects on preventing blood transfusion compared to placebo. The comparative effects of ESAs compared with another ESA on preventing blood transfusions were uncertain, in low to very low certainty evidence. Effects on death (any cause) were uncertain for epoetin alfa (OR 0.79, 95% CI 0.51 to 1.22; low certainty evidence), epoetin beta (OR 0.69, 95% CI 0.40 to 1.20; low certainty evidence), methoxy polyethylene glycol-epoetin beta (OR 1.07, 95% CI 0.67 to 1.71; very low certainty evidence), a biosimilar epoetin (OR 0.80, 95% CI 0.47 to 1.36; low certainty evidence) and a biosimilar darbepoetin alfa (OR 1.63, 95% CI 0.51 to 5.23; very low certainty evidence) compared to placebo. There was probably no difference between darbepoetin alfa and placebo on the odds of death (any cause) (OR 0.99, 95% CI 0.81 to 1.21; moderate certainty evidence). The comparative effects of ESAs compared with another ESA on death (any cause) were uncertain in low to very low certainty evidence. Epoetin beta probably increased the odds of hypertension when compared to placebo (OR 2.17, 95% CI 1.17 to 4.00; moderate certainty evidence). Compared to placebo, epoetin alfa (OR 2.10, 95% CI 1.22 to 3.59; very low certainty evidence), darbepoetin alfa (OR 1.88, 95% CI 1.12 to 3.14; low certainty evidence) and methoxy polyethylene glycol-epoetin beta (OR 1.98, 95% CI 1.05 to 3.74; low certainty evidence) may increase the odds of hypertension, but a biosimilar epoetin (OR 1.88, 95% CI 0.96 to 3.67; low certainty evidence) and biosimilar darbepoetin alfa (OR 1.98, 95% CI 0.84 to 4.66; low certainty evidence) had uncertain effects on hypertension. The comparative effects of all ESAs compared with another ESA, placebo or no treatment on cardiovascular death, myocardial infarction, stroke, vascular access thrombosis, kidney failure, and breathlessness were uncertain. Network analysis for fatigue was not possible due to sparse data.  AUTHORS' CONCLUSIONS: The comparative effects of different ESAs on blood transfusions, death (any cause and cardiovascular), major cardiovascular events, myocardial infarction, stroke, vascular access thrombosis, kidney failure, fatigue and breathlessness were uncertain.

Comparative effectiveness of metformin versus sulfonylureas on kidney function decline or death among patients with reduced kidney function: a retrospective cohort study

BACKGROUND

Diabetes often causes kidney disease. In this study, we sought to evaluate if metformin use was associated with death or kidney events in patients with diabetes and concurrent reduced kidney function.

METHODS

We used data from the Veterans Health Administration, Medicare and National Death Index databases to assemble a national retrospective cohort of veterans who were using metformin or sulfonylureas from 2001 through 2016 and who began follow-up at an estimated glomerular filtration rate (eGFR) of less than 60 mL/min/1.73 m². The primary composite outcome was a kidney event (i.e., 40% decline in eGFR or end-stage renal disease) or death. The secondary outcome was a kidney event (eGFR decline or end-stage renal disease). We weighted the cohort using propensity scores and used Cox proportional models to estimate the cause-specific hazard of outcomes and of treatment nonpersistence as a competing risk. We stratified follow-up into 2 periods, namely the first 360 days from the start of follow-up, and 361 days and beyond.

RESULTS

In the first 360 days, the propensity score-weighted cohort included 24 883 patients who used metformin and 24 998 who used sulfonylureas. There were 33.5 (95% confidence interval [CI] 30.9-36.3) and 43.0 (95% CI 40.1-46.0) deaths or kidney events per 1000 person-years for patients who used metformin or sulfonylureas, respectively (hazard ratio [HR] 0.78, 95% CI 0.71-0.85). For the secondary outcome of kidney events, the HR was 0.94 (95% CI 0.67-1.33). In the second period from 361 days onward, the primary outcome event rate was 26.5 (95% CI 24.7-28.5) per 1000 person-years for those who used metformin, compared with 36.3 (95% CI 34.2-38.6) per 1000 person-years for those who used sulfonylureas (HR 0.73, 95% CI 0.67-0.79). Results were consistent for kidney events alone (HR 0.73, 95% CI 0.59-0.91).

INTERPRETATION

Metformin use for 361 days or longer after reaching an eGFR of less than 60 mL/min/1.73 m² was associated with decreased likelihood of kidney events or death in patients with diabetes, compared with use of sulfonylureas. Metformin provided end-organ protection, in addition to glucose control.

Metformin Attenuates Hyperglycaemia-Stimulated Pro-Fibrotic Gene Expression in Adventitial Fibroblasts via Inhibition of Discoidin Domain Receptor 2

Molecular mechanisms underlying the diverse therapeutic effects of anti-diabetic metformin, beyond its anti-hyperglycaemic effects, remain largely unclear. Metformin is reported to reduce the long-term complications of diabetes, including cardiovascular fibrosis and remodelling. Our recent investigations show that Discoidin Domain Receptor 2 (DDR2), a Collagen receptor tyrosine kinase, has an obligate regulatory role in Collagen type I gene expression in cardiac and vascular adventitial fibroblasts, and that it may be a molecular link between arterial fibrosis and metabolic syndrome in rhesus monkeys. Using gene knockdown and overexpression approaches, the present study examined whether DDR2 is a target of metformin and whether, by targeting DDR2, it inhibits Fibronectin and Collagen type I expression in rat aortic adventitial fibroblasts exposed to hyperglycaemic conditions. Metformin was found to attenuate hyperglycaemia-induced increase in DDR2 mRNA and protein expression by inhibiting TGF-β1/SMAD2/3 signalling that mediates the stimulatory effect of hyperglycaemia on DDR2 expression. Metformin also inhibited DDR2-dependent expression of Fibronectin and Collagen type I, indicating that it regulates these matrix proteins via DDR2 inhibition. The findings identify DDR2, a mediator of cardiovascular remodelling, as a molecular target of metformin, thereby uncovering the molecular basis of its protective role in vascular fibrosis and possibly cardiac fibrosis associated with diabetic cardiomyopathy.

Metformin as a Potential Antitumor Agent

Some recent findings suggest that metformin, an oral antidiabetic drug, may have antitumor properties. Studies have shown that metformin can alter cell metabolism, both tumor and immune cells, which can greatly influence disease outcome. In this review, we discuss the potential mechanisms in which metformin can directly induce apoptosis of tumor cells as well as mechanisms in which metformin can elicit or enhance antitumor immune response.

Part Six: Antidiabetic Medication Benefits Beyond Glucose Lowering in Older People

Older people with type 2 diabetes are at an increased risk for macrovascular (damage to arteries that can lead to myocardial infarction or stroke) and microvascular (damage to small blood vessels including retinopathy and nephropathy) disease. Since 2008, newly approved antidiabetic medications have been required to show cardiovascular safety as part of the US Food and Drug Administration approval process. Since this time, new data have emerged regarding the differences between agents in terms of reducing diabetes-related complications. Older people often are at risk for or currently have one or more diabetes-related complication. When managing antidiabetic medication in older people, it is imperative to consider the risk versus benefit of each medication and to use agents that have proven benefits.

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.

Attenuated Risk Association of End-Stage Kidney Disease with Metformin in Type 2 Diabetes with eGFR Categories 1–4

Type 2 diabetes (T2D)-associated end-stage kidney disease (ESKD) is a global burden, while the renoprotective effects of metformin remain controversial. In a population-based cohort (2002–2018) including 96,643 patients with T2D observed for 0.7 million person-years, we estimated the risk association of metformin and its dose-relationship with ESKD in a propensity-score overlap-weighting (PS-OW) cohort by eGFR categories. Amongst 96,643, 83,881 (86.8%) had eGFR-G1/G2 (≥60 mL/min/1.73 m²), 8762 (9.1%) had eGFR-G3a (≥45–60 mL/min/1.73 m²), 3051 (3.2%) had eGFR-G3b (≥30–45 mL/min/1.73 m²), and 949 (1.0%) had eGFR-G4 (≥15–30 mL/min/1.73 m²). The respective proportions of metformin users in these eGFR categories were 95.1%, 81.9%, 53.8%, and 20.8%. In the PS-OW cohort with 88,771 new-metformin and 7872 other oral glucose-lowering-drugs (OGLDs) users, the respective incidence rates of ESKD were 2.8 versus 22.4/1000 person-years. Metformin use associated with reduced risk of ESKD (hazard ratio (HR) = 0.43 [95% CI: 0.35–0.52] in eGFR-G1/G2, 0.64 [0.52–0.79] in eGFR-G3a, 0.67 [0.56–0.80] in eGFR-G3b, and 0.63 [0.48–0.83] in eGFR-G4). Metformin use was associated with reduced or neutral risk of major adverse cardiovascular events (MACE) (7.2 versus 16.0/1000 person-years) and all-cause mortality (14.6 versus 65.1/1000 person-years). Time-weighted mean daily metformin dose was 1000 mg in eGFR-G1/G2, 850 mg in eGFR-G3a, 650 mg in eGFR-G3b, and 500 mg in eGFR-G4. In a subcohort of 14,766 patients observed for 0.1 million person-years, the respective incidence rates of lactic acidosis and HR in metformin users and non-users were 42.5 versus 226.4 events/100,000 person-years (p = 0.03) for eGFR-G1/G2 (HR = 0.57, 0.25–1.30) and 54.5 versus 300.6 events/100,000 person-years (p = 0.01) for eGFR-G3/G4 (HR = 0.49, 0.19–1.30). These real-world data underscore the major benefits and low risk of lactic acidosis with metformin use down to an eGFR of 30 mL/min/1.73 m² and possibly even 15 mL/min/1.73 m², while reinforcing the importance of dose adjustment and frequent monitoring of eGFR.

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.

A combination of metformin and insulin improve cardiovascular and cerebrovascular risk factors in individuals with type 1 diabetes mellitus

BACKGROUND

This study aims to further clarify whether the addition of metformin to insulin treatment improve cardiovascular and cerebrovascular risk factors in individuals with T1DM.

METHODS

Electronic databases were searched for randomized controlled trials in which the efficacy and safety of metformin were compared with those of a placebo for risk factors of cardiovascular and cerebrovascular disease among individuals with T1DM, and a meta-analysis was conducted.

RESULTS

Thirteen cardiovascular studies were identified. In the metformin group, mean carotid intimal media thickness was significantly reduced by 0.03 mm, ascending aortic pulse wave velocity by 6.3 m/s, descending aortic wall shear stress by 1.77 dyn/cm² (P = 0.02), insulin daily dose by 0.05 U/kg/d, body weight by 2.27 kg, fat-free mass by 1.32 kg, body mass index by 0.58 kg/m², hip circumference by 0.29 m, and low-density lipoprotein by 0.16 mmol/L, all above are P < 0.05. In the metformin group, flow-mediated dilation was increased by 1.29 %, glucose infusion rate/insulin by 18.22 mg/(kg⋅min)/μIU/μL, and waist-to-hip ratio by 0.02, all above are P < 0.00001. The metformin group showed no differences in blood pressure, reactive hyperemia index, waist circumference, triglyceride, total cholesterol, high-density lipoprotein cholesterol, or body mass index Z score. For cerebrovascular studies were identified. But none of them had a risk factor assessment.

CONCLUSIONS

Metformin can ameliorate cardiovascular and cerebrovascular risk factors through non-hypoglycemic multiple pathways in individuals with T1DM.

Emerging role of neutrophil extracellular traps in the complications of diabetes mellitus

Immune dysfunction is widely regarded as one of the central tenants underpinning the pathophysiology of diabetes mellitus (DM) and its complications. When discussing immunity, the role of neutrophils must be accounted for: neutrophils are the most abundant of the circulating immune cells and are the first to be recruited to sites of inflammation, where they contribute to host defense via phagocytosis, degranulation, and extrusion of neutrophil extracellular traps (NETs). NETs are composed of DNA associated with nuclear and cytosolic neutrophil proteins. Although originally reported as an antimicrobial strategy to prevent microbial dissemination, a growing body of evidence has implicated NETs in the pathophysiology of various autoimmune and metabolic disorders. In these disorders, NETs propagate a pathologic inflammatory response with consequent tissue injury and thrombosis. Many diabetic complications—such as stroke, retinopathy, impaired wound healing, and coronary artery disease—involve these mechanisms. Therefore, in this review, we discuss laboratory and clinical data informing our understanding of the role of NETs in the development of these complications. NET markers, including myeloperoxidase, citrullinated histone H3, neutrophil elastase, and cell-free double-stranded DNA, can easily be measured in serum or be detected via immunohistochemical/immunocytochemical staining of tissue specimens. Therefore, NET constituents potentially constitute reliable biomarkers for use in the management of diabetic patients. However, no NET-targeting drug is currently approved for the treatment of diabetic complications; a candidate drug will require the outcomes of well-designed, robust clinical trials assessing whether NET inhibition can benefit patients in terms of morbidity, quality of life, health expenditures, and mortality. Therefore, much work remains to be done in translating these encouraging pieces of data into clinical trials for NET-targeting medications to be used in the clinic.

The effect of chronic exposure to metformin in a new type-2 diabetic NONcNZO10/LtJ mouse model of stroke

BACKGROUND

Diabetes is an independent risk factor of stroke and previous studies have confirmed that diabetic patients and animals experience poorer clinical outcomes following stroke. In this study, we aim to determine the effect of chronic exposure of the first-line antidiabetic agent, metformin, to restore euglycemia and to impact brain cell death following stroke in a new type-2 diabetes, NONcNZO10/LtJ (RCS-10) mouse model of stroke.

METHODS

Male RCS-10 mice received a moderate (11%) fat diet post-weaning, at 4 weeks of age, and became diabetic by 12-14 weeks, thus resembling human maturity-onset diabetes. The mice received either metformin or vehicle for 4 weeks before undergoing a hypoxic/ischemic (HI) insult. Blood samples were collected pre-, post-treatment, and post HI for glucose and lipid measurements, and brains were analyzed for infarct size, glial activation, neuronal cell death, and metformin-mediated adenosine monophosphate-activated protein kinase (AMPK) signaling at 48 h post HI.

RESULTS

Pretreatment with metformin maintained euglycemia for 4 weeks but did not change body weight or lipid profile. Metformin treatment significantly enhanced the microglial Bfl-1 mRNA expression and showed a non-significant increase in GFAP mRNA, however, GFAP protein levels were reduced. Metformin treatment slightly increased neuronal NeuN and MAP-2 protein levels and significantly reduced overall mortality post HI but did not elicit any significant change in infarct size.

CONCLUSION

The study suggests that the prolonged effect of metformin-induced euglycemia promoted the microglial activation, reduced neuronal cell death, and improved the overall survival following stroke, without any change in infarct size.

The 2021-2022 position of Brazilian Diabetes Society on diabetic kidney disease (DKD) management: an evidence-based guideline to clinical practice. Screening and treatment of hyperglycemia, arterial hypertension, and dyslipidemia in the patient with DKD

BACKGROUND

Diabetic kidney disease is the leading cause of end-stage renal disease and is associated with increased morbidity and mortality. This review is an authorized literal translation of part of the Brazilian Diabetes Society (SBD) Guidelines 2021-2022. This evidence-based guideline provides guidance on the correct management of Diabetic Kidney Disease (DKD) in clinical practice.

METHODS

The methodology was published elsewhere in previous SBD guidelines and was approved by the internal institutional Steering Committee for publication. Briefly, the Brazilian Diabetes Society indicated 14 experts to constitute the Central Committee, designed to regulate methodology, review the manuscripts, and make judgments on degrees of recommendations and levels of evidence. SBD Renal Disease Department drafted the manuscript selecting key clinical questions to make a narrative review using MEDLINE via PubMed, with the best evidence available including high-quality clinical trials, metanalysis, and large observational studies related to DKD diagnosis and treatment, by using the MeSH terms [diabetes], [type 2 diabetes], [type 1 diabetes] and [chronic kidney disease].

RESULTS

The extensive review of the literature made by the 14 members of the Central Committee defined 24 recommendations. Three levels of evidence were considered: A. Data from more than 1 randomized clinical trial or 1 metanalysis of randomized clinical trials with low heterogeneity (I² < 40%). B. Data from metanalysis, including large observational studies, a single randomized clinical trial, or a pre-specified subgroup analysis. C: Data from small or non-randomized studies, exploratory analyses, or consensus of expert opinion. The degree of recommendation was obtained based on a poll sent to the panelists, using the following criteria: Grade I: when more than 90% of agreement; Grade IIa 75-89% of agreement; IIb 50-74% of agreement, and III, when most of the panelist recommends against a defined treatment.

CONCLUSIONS

To prevent or at least postpone the advanced stages of DKD with the associated cardiovascular complications, intensive glycemic and blood pressure control are required, as well as the use of renin-angiotensin-aldosterone system blocker agents such as ARB, ACEI, and MRA. Recently, SGLT2 inhibitors and GLP1 receptor agonists have been added to the therapeutic arsenal, with well-proven benefits regarding kidney protection and patients' survival.

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.

A Clinical Perspective of the Multifaceted Mechanism of Metformin in Diabetes, Infections, Cognitive Dysfunction, and Cancer

In type 2 diabetes, ecological and lifecourse factors may interact with the host microbiota to influence expression of his/her genomes causing perturbation of interconnecting biological pathways with diverse clinical course. Metformin is a plant-based or plant-derived medicinal product used for the treatment of type 2 diabetes for over 60 years and is an essential drug listed by the World Health Organization. By reducing mitochondrial oxidative phosphorylation and adenosine triphosphate (ATP) production, metformin increased AMP (adenosine monophosphate)-activated protein kinase (AMPK) activity and altered cellular redox state with reduced glucagon activity, endogenous glucose production, lipogenesis, and protein synthesis. Metformin modulated immune response by directly reducing neutrophil to lymphocyte ratio and improving the phagocytic function of immune cells. By increasing the relative abundance of mucin-producing and short-chain-fatty-acid-producing gut microbes, metformin further improved the host inflammatory and metabolic milieu. Experimentally, metformin promoted apoptosis and reduced proliferation of cancer cells by reducing their oxygen consumption and modulating the microenvironment. Both clinical and mechanistic studies support the pluripotent effects of metformin on reducing cardiovascular–renal events, infection, cancer, cognitive dysfunction, and all-cause death in type 2 diabetes, making this low-cost medication a fundamental therapy for individualization of other glucose-lowering drugs in type 2 diabetes. Further research into the effects of metformin on cognitive function, infection and cancer, especially in people without diabetes, will provide new insights into the therapeutic value of metformin in our pursuit of prevention and treatment of ageing-related as well as acute and chronic diseases beyond diabetes.

PGC-1α inhibits the NLRP3 inflammasome via preserving mitochondrial viability to protect kidney fibrosis

The NLRP3 inflammasome is activated by mitochondrial damage and contributes to kidney fibrosis. However, it is unknown whether PGC-1α, a key mitochondrial biogenesis regulator, modulates NLRP3 inflammasome in kidney injury. Primary renal tubular epithelial cells (RTECs) were isolated from C57BL/6 mice. The NLRP3 inflammasome, mitochondrial dynamics and morphology, oxidative stress, and cell injury markers were examined in RTECs treated by TGF-β1 with or without Ppargc1a plasmid, PGC-1α activator (metformin), and siPGC-1α. In vivo, adenine-fed and unilateral ureteral obstruction (UUO) mice were treated with metformin. In vitro, TGF-β1 treatment to RTECs suppressed the expressions of PGC-1α and mitochondrial dynamic-related genes. The NLRP3 inflammasome was also activated and the expression of fibrotic and cell injury markers was increased. PGC-1α induction with the plasmid and metformin improved mitochondrial dynamics and morphology and attenuated the NLRP3 inflammasome and cell injury. The opposite changes were observed by siPGC-1α. The oxidative stress levels, which are inducers of the NLRP3 inflammasome, were increased and the expression of TNFAIP3, a negative regulator of NLRP3 inflammasome regulated by PGC-1α, was decreased by TGF-β1 and siPGC-1α. However, PGC-1α restoration reversed these alterations. In vivo, adenine-fed and UUO mice models showed suppression of PGC-1α and TNFAIP3 and dysregulated mitochondrial dynamics. Moreover, the activation of oxidative stress and NLRP3 inflammasome, and kidney fibrosis were increased in these mice. However, these changes were significantly reversed by metformin. This study demonstrated that kidney injury was ameliorated by PGC-1α-induced inactivation of the NLRP3 inflammasome via modulation of mitochondrial viability and dynamics.

Metformin use and cardiovascular outcomes in patients with diabetes and chronic kidney disease: a nationwide cohort study

BACKGROUND

Metformin has recently been shown not to increase the risk of lactic acidosis in patients with chronic kidney disease (CKD). Thus, the criteria for metformin use in this population has expanded. However, the relationship between metformin use and clinical outcomes in CKD remains controversial.

METHODS

This study considered data from 97,713 diabetes patients with an estimated glomerular filtration rate of <60 mL/min/1.73 m2. The primary outcome was major adverse cardiac and cerebrovascular events (MACCE), and the secondary outcomes were all-cause mortality and incident end-stage renal disease (ESRD).

RESULTS

Metformin users had a significantly higher risk of MACCE than non-users (hazard ratio [HR], 1.20; 95% confidence interval [CI], 1.14-1.26; p < 0.001). However, metformin users had a lower risk of all-cause mortality (HR, 0.78; 95% CI, 0.74-0.81; p < 0.001) and ESRD (HR, 0.44; 95% CI, 0.42-0.47; p < 0.001) during follow-up than non-users did. The relationships between metformin use and clinical outcomes remained consistent in propensity score matching analyses and subgroup analyses of patients with adequate adherence to anti-diabetes medication.

CONCLUSION

Treatment with metformin was associated with an increased risk of MACCE in patients with diabetes and CKD. However, metformin users had a lower risk of all-cause mortality and ESRD during follow-up than non-users did. Therefore, metformin needs to be carefully used in patients with CKD.

Targeting Cardiovascular Risk Factors Through Dietary Adaptations and Caloric Restriction Mimetics

The average human life expectancy continues to rise globally and so does the prevalence and absolute burden of cardiovascular disease. Dietary restriction promotes longevity and improves various cardiovascular risk factors, including hypertension, obesity, diabetes mellitus, and metabolic syndrome. However, low adherence to caloric restriction renders this stringent dietary intervention challenging to adopt as a standard practice for cardiovascular disease prevention. Hence, alternative eating patterns and strategies that recapitulate the salutary benefits of caloric restriction are under intense investigation. Here, we first provide an overview of alternative interventions, including intermittent fasting, alternate-day fasting and the Mediterranean diet, along with their cardiometabolic effects in animal models and humans. We then present emerging pharmacological alternatives, including spermidine, NAD+ precursors, resveratrol, and metformin, as promising caloric restriction mimetics, and briefly touch on the mechanisms underpinning their cardiometabolic and health-promoting effects. We conclude that implementation of feasible dietary approaches holds the promise to attenuate the burden of cardiovascular disease and facilitate healthy aging in humans.

Safety and effectiveness of metformin in patients with reduced renal function: A systematic review

AIM

To examine clinical and safety outcomes associated with metformin use in patients with impaired renal function.

MATERIALS AND METHODS

We searched PubMed and Embase databases from inception to August 2020, supplementing our search with a review of investigator files and reference lists of included studies. Any study reporting original data on metformin and patient-centred outcomes in patients with impaired renal function, defined as an estimated glomerular filtration rate (eGFR) of less than 60 mL/min/1.73m² , was included. Post hoc meta-analysis was performed for the outcomes of mortality, cardiovascular events and acidosis.

RESULTS

Nine small prospective studies enrolling patients with significantly impaired renal function identified only one case of clinically apparent lactic acidosis. Among 13 larger retrospective studies, seven examined the risk of mortality across patient subgroups; meta-analysis showed reductions in overall mortality at an eGFR of 45 mL/min/1.73m² or higher but not at an eGFR of less than 45 mL/min/1.73m² . Eight retrospective studies evaluated acidosis as an outcome; meta-analysis showed no increase in risk of acidosis except at an eGFR of less than 30 mL/min/1.73m² , in which group the HR was 1.97 (95% CI 1.03-3.77).

CONCLUSIONS

The literature shows metformin to be associated with reduced mortality and no increased risk of acidosis at an eGFR of 45 mL/min/1.73m² or higher. Metformin appears to be associated with fewer benefits and possible increases in the risk of acidosis at an eGFR of less than 30 mL/min/1.73m² . Consistent with US Food and Drug Administration guidelines, metformin should not be used at an eGFR less than 30 mL/min/1.73m² , and further research on its risk-benefit profile at eGFR values approaching 30 mL/min/1.73m² is warranted.

Metformin Therapy in Autosomal Dominant Polycystic Kidney Disease: A Feasibility Study

RATIONALE & OBJECTIVE

Autosomal dominant polycystic kidney disease (ADPKD) is a common inherited disorder that leads to kidney failure and has few treatment options. Metformin is well tolerated and safe in other patient populations. The primary objective of this clinical trial was to determine the safety and tolerability of metformin in patients with ADPKD and without diabetes mellitus.

STUDY DESIGN

Prospective, randomized, controlled, double-blind clinical trial.

SETTING & PARTICIPANTS

N=51 adults 30-60 years of age with ADPKD, without diabetes, and an estimated glomerular filtration rate (eGFR) 50-80 mL/min/1.73 m².

INTERVENTION

Metformin (maximum dose 2,000 mg/day) or placebo for 12 months.

OUTCOMES

Co-primary endpoints were the percentage of participants in each group prescribed at the end of the 12-month period: (a) the full randomized dose, and (b) at least 50% of the randomized dose. Secondary and exploratory outcomes were the effect of metformin compared to placebo on (a) percent change in TKV referenced to height (htTKV in mL/m) and (b) change in eGFR over a 12-month period.

RESULTS

Mean age was 48 ± 8 years and eGFR was 70 ± 14 mL/min/1.73m². The metformin group had no cases of lactic acidosis and there was one episode of mild hypoglycemia in each group. Participants in the metformin group reported more adverse symptoms, mostly related to gastrointestinal symptoms. 11 of 22 (50%) of metformin-treated participants completed the treatment phase on the full dose compared to 23 of 23 (100%) in the placebo group. 82% of participants on metformin tolerated at least 50% of the dose, compared to 100% in the placebo group. In exploratory analyses, changes in height-adjusted total kidney volume or eGFR were not significantly different between groups.

LIMITATIONS

Short study duration.

CONCLUSIONS

50% or more of the maximal metformin dose was safe and well tolerated over 12 months in patients with ADPKD. Safety of other preparations of metformin as well as its efficacy should be tested in future clinical trials.

Efficacy of metformin monotherapy in US veterans with type 2 diabetes and preexisting chronic kidney disease stage 3

AIM

To evaluate the glycaemic efficacy of metformin in people with type 2 diabetes (T2D) and stage 3 chronic kidney disease (CKD3).

PARTICIPANTS AND METHODS

This was a retrospective study including 145980 US veterans with T2D and an estimated glomerular filtration rate (eGFR) ≥30 mL/min/1.73 m² who initiated metformin monotherapy between November 1999 and July 2017. Propensity-score-matched cohorts were generated based on baseline variables associated with CKD3 (eGFR 30-59 mL/min/1.73 m² ) to evaluate the independent association between CKD3 and metformin discontinuation, the addition of a second hypoglycaemic agent, and changes in glycated haemoglobin (HbA1c) from baseline in those with and without CKD3. Associations were examined using the Kaplan-Meier method and multivariable regression models, adjusted for baseline and 12-month average metformin dose.

RESULTS

The mean age of the entire cohort was 60.7 years, and 95% of the cohort were men, 21% were African American and 9% had CKD3. In the adjusted analyses, patients with CKD3 had a higher risk of metformin discontinuation or addition of a second hypoglycaemic agent, as compared with patients without CKD (hazard ratio [HR] 1.22, 95% confidence interval [CI] 1.19-1.26, and HR 1.26, 95% CI 1.13-1.40, respectively). Among metformin monotherapy users, there were no differences in the average HbA1c reduction from baseline to 12 or 24 months between patients with and without CKD3.

CONCLUSIONS

Individuals with CKD3 and T2D were at increased risk of metformin monotherapy failure. However, the HbA1c-lowering efficacy of metformin was similar in patients with and without CKD3, highlighting that metformin is a valuable treatment option for newly treated individuals with T2D and CKD3.

[Treatment of diabetes mellitus in perioperative medicine-an update]

Patients with diabetes who undergo a surgical intervention have an increased risk of metabolic derailment, anesthesiological complications, postoperative infections and cardiovascular events. The treatment of diabetes mellitus is subject to a continuous further development due to pharmaceutical and technical innovations. This article presents the implications of the current concepts of diabetes treatment for perioperative medicine, particularly the changes due to new oral antidiabetic agents and insulin pump treatment. Some of the currently available guidelines are discussed with respect to the care of diabetes patients in childhood and adulthood in connection with an operation. Finally, possible perspectives in the field of monitoring and treatment of diabetes patients are discussed.

Glucose-lowering pharmacotherapies in Chinese adults with type 2 diabetes and cardiovascular disease or chronic kidney disease. An expert consensus reported by the Chinese Diabetes Society and the Chinese Society of Endocrinology

Patients with type 2 diabetes mellitus (T2DM) are at risk of developing atherosclerotic cardiovascular disease (ASCVD) and chronic kidney disease (CKD), which are important causes of disabling and death in patients with T2DM. For the prevention and management of ASCVD or CKD, cardiovascular risk factors should be systematically evaluated, and ASCVD and CKD should be screened in patients with T2DM. In this consensus, we recommended that metformin should be used as the first-line therapy for patients with T2DM and ASCVD or very high cardiovascular risk, heart failure (HF) or CKD, and should be retained in the treatment regimen unless contraindicated or not tolerated. In patients with T2DM and established ASCVD or very high cardiovascular risk, addition of a glucagon-like peptide 1 receptor agonist (GLP-1RA) or sodium-glucose cotransporter type 2 (SGLT2) inhibitor with proven cardiovascular benefits should be considered independent of individualised glycated haemoglobin (HbA_1C ) targets. In patients with T2DM and HF, an SGLT2 inhibitor should be preferably added regardless of HbA_1C levels. In patients with T2DM and CKD, SGLT2 inhibitors should be preferred for the combination therapy independent of individualised HbA_1C targets, and GLP-1RAs with proven renal benefits would be alternative if SGLT2 inhibitors are contraindicated. Moreover, the prevention of hypoglycaemia and management of multiple risk factors by comprehensive regimen, including lifestyle intervention, antihypertensive therapies, lipid-lowering treatment and antiplatelet therapies, should be kept in mind in treating patients with T2DM and ASCVD, HF or CKD.

Cardiovascular and renal safety of metformin in patients with diabetes and moderate or severe chronic kidney disease: Observations from the EXSCEL and SAVOR-TIMI 53 cardiovascular outcomes trials

AIM

To provide evidence on the cardiovascular and renal safety of metformin in chronic kidney disease (CKD) stages 3 to 4.

MATERIALS AND METHODS

This post hoc analysis compared participants with an estimated glomerular filtration rate (eGFR) of 15 to 59 mL/min/1.73m² in the Exenatide Study of Cardiovascular Event Lowering (EXSCEL) and the Saxagliptin and Cardiovascular Outcomes in Patients With Type 2 Diabetes Mellitus (SAVOR-TIMI 53) trials taking metformin, with those not exposed to metformin during these trials, using a propensity-matching approach. Adjusted Cox proportional hazards models were used to assess risk of major adverse cardiovascular events (MACE) and all-cause mortality (ACM). Metformin effect on eGFR slope was calculated using a mixed-model repeated measures analysis, and the number of lactic acidosis events was tabulated.

RESULTS

No strong trend for lower metformin doses with lower eGFR values was observed in either the EXSCEL or SAVOR-TIMI 53 trials. In the 1745 metformin-using participants matched to non-metformin users, metformin had neutral effects on MACE (hazard ratio [HR] 0.91, 95% confidence interval [CI] 0.76-1.08; P = 0.28) and ACM (HR 0.86, 95% CI 0.70-1.07; P = 0.18), with no interaction by CKD stage, or with use of exenatide or saxagliptin. An improvement in eGFR slope was observed with metformin in the CKD stage 3B cohort in SAVOR-TIMI 53, but not in other groups.

CONCLUSIONS

This analysis of participants with CKD stages 3 to 4 from two cardiovascular outcomes trials supports the cardiorenal safety of metformin, but does not suggest a consistent benefit on MACE, ACM, or eGFR slope across this population.

Mechanism and application of metformin in kidney diseases: An update

Metformin is an oral antihyperglycemic drug widely used to treat type 2 diabetes mellitus (T2DM), acting via indirect activation of 5' Adenosine monophosphate-activated Protein Kinase (AMPK). Beyond the anti-diabetic effect, accumulative pieces of evidence have revealed that metformin also everts a beneficial effect in diverse kidney diseases. In various acute kidney diseases (AKI) animal models, metformin protects renal tubular cells from inflammation, apoptosis, reactive oxygen stress (ROS), endoplasmic reticulum (ER) stress, epithelial-mesenchymal transition (EMT) via AMPK activation. In diabetic kidney disease (DKD), metformin also alleviates podocyte loss, mesangial cells apoptosis, and tubular cells senescence through AMPK-mediated signaling pathways. Besides, metformin inhibits cystic fibrosis transmembrane conductance regulator (CFTR)-mediated fluids secretion and the mammalian target of rapamycin (mTOR)-involved cyst formation negatively regulated by AMPK in autosomal dominant polycystic kidney disease (APDKD). Furthermore, metformin also contributes to the alleviation of urolithiasis and renal cell carcinoma (RCC). As the common pathway for chronic kidney disease (CKD) progressing towards end-stage renal disease (ESRD), renal fibrosis is ameliorated by metformin, to a great extent dependent on AMPK activation. However, clinical data are not always consistent with preclinical data, some clinical investigations showed the unmeaningful even detrimental effect of metformin on T2DM patients with kidney diseases. Most importantly, metformin-associated lactic acidosis (MALA) is a vital issue restricting the application of metformin. Thus, we conclude the application of metformin in kidney diseases and uncover the underlying molecular mechanisms in this review.

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.

Metformin use in patients with type 2 diabetes mellitus and chronic kidney disease: An evidence-based review

INTRODUCTION

Practice guidelines advise caution on the use of metformin in patients with type 2 diabetes mellitus with chronic kidney disease (CKD). This review aims to examine the evidence for the benefits and risks of metformin use in patients with T2DM and CKD.

METHODS

The Cochrane Database of Systematic Reviews, the Cochrane Central Register of Controlled Trials and PubMed were searched; the references of selected papers were hand searched. Systematic reviews, randomised controlled trials, cohort studies, case series and case-control studies were included. The full text of selected articles was reviewed. The outcomes studied were all-cause mortality, cardiovascular complications, lactic acidosis and worsening of renal function. Recommendations were graded according to the Scottish Intercollegiate Guidelines Network system.

RESULTS

A total of 139 unique articles were identified, 14 of which met the inclusion criteria and were selected for full-text review. Four cohort studies reported an association between metformin use and improved all-cause mortality in CKD stage 4 and better. Two cohort studies reported improved cardiovascular outcomes with metformin use. Four cohort studies, 1 case series and 1 case-control study reported no significant association between metformin use and an increased risk of lactic acidosis in CKD. There is a moderate level of evidence to support reduced mortality, improved cardiovascular outcomes and a low risk of lactic acidosis with metformin use in patients with T2DM and with CKD stage 4 and above.

CONCLUSION

Existing recommendations to restrict metformin use in diabetes patients with CKD need to be reviewed in light of emerging evidence supporting its overall benefits in these patients.

Metformin prevents brain injury after cardiopulmonary resuscitation by inhibiting the endoplasmic reticulum stress response and activating AMPK-mediated autophagy

BACKGROUND AND AIMS

The neurological damage caused by cardiac arrest (CA) can seriously affect quality of life. We investigated the effect of metformin pretreatment on brain injury and survival in a rat CA/cardiopulmonary resuscitation (CPR) model.

METHODS AND RESULTS

After 14 days of pretreatment with metformin, rats underwent 9 minutes of asphyxia CA/CPR. Survival was evaluated 7 days after restoration of spontaneous circulation; neurological deficit scale (NDS) score was evaluated at days 1, 3, and 7. Proteins related to the endoplasmic reticulum (ER) stress response and autophagy were measured using immunoblotting. Seven-day survival was significantly improved and NDS score was significantly improved in rats pretreated with metformin. Metformin enhanced AMPK-induced autophagy activation. AMPK and autophagy inhibitors removed the metformin neuroprotective effect. Although metformin inhibited the ER stress response, its inhibitory effect was weaker than 4-PBA.

CONCLUSION

In a CA/CPR rat model, 14-day pretreatment with metformin has a neuroprotective effect. This effect is closely related to the activation of AMPK-induced autophagy and inhibition of the ER stress response. Long-term use of metformin can reduce brain damage following CA/CPR.

Monitoring and management of hyperglycemia in patients with advanced diabetic kidney disease

Diabetes mellitus is the leading cause of end-stage renal disease, and uncontrolled hyperglycemia is directly related to the increased mortality in this setting. As kidney function decreases, it becomes more challenging to control blood glucose since the risk of hypoglycemia increases. Decreased appetite, changes in glycaemia homeostasis, along with reduced renal excretion of anti-hyperglycemic drugs tend to facilitate the occurrence of hypoglycemia, despite the paradoxical occurrence of insulin resistance in advanced kidney disease. Thus, in patients using insulin and/or oral anti-hyperglycemic agents, dynamic adjustments with drug dose reduction or drug switching are often necessary. Furthermore, in addition to consider these pharmacokinetics alterations, it is of utmost importance to choose drugs with proven cardio-renal benefits in this setting, such as sodium-glucose co-transporter 2 inhibitors and glucagon-like peptide 1 receptor agonists. In this review, we summarize the indications and contraindications, titration of doses and side effects of the available anti-hyperglycemic agents in the presence of advanced diabetic kidney disease (DKD) and dialysis, highlighting the risks and benefits of the different agents. Additionally, basic renal function assessment and monitoring of glycemic control in DKD will be evaluated in order to guide the use of drugs and define the glycemic targets to be achieved.

SGLT-2 inhibitors may be targeting higher risk patients with diabetes possibly justifying higher cost: Single center repeated cross-sectional analysis

INTRODUCTION

We studied the use of all hypoglycemic agents in periods before and after introduction of SGLT-2 inhibitors in the USA by repeated cross sectional analysis to initially assess improvement in HbA1c control among patients with type 2 diabetes and hypertension. We sought to identify changes in glucose management related to the availability of the SGLT-2 inhibiting agents. We hypothesized that patients transitioned to SGLT-2 inhibitor-based therapy represented a higher risk group that derived benefits in terms of Hba1c control.

METHODS

Deidentified records of patients seen at least twice during the relevant time periods at Joslin Clinic between January 1, 2010 and December 31, 2012 and/or between January 1, 2014 and December 31, 2016 were examined. Records required all of the following: demographic information of gender, age, height, weight, BMI, HbA1c, eGFR, blood pressure, smoking status and completed medication lists.

RESULTS

10,191 patients met criteria for analysis, 7769 seen in period 1 and 6576 in period 2. 4625 patients were seen in both periods. The group of patients defined by SGLT-2 use had significantly higher BMI and HbA1c. Notable shifts in medication use were observed as SGLT-2 use increased from none to 14%. Increased use (all p < 0.001) of GLP-1 agents (16.0 to 23.8%), insulin (56.1 to 60.5%) and statins (78.4 to 81.5%) and statistically significant decreases (all p < 0.001) in use of biguanides (69.5 to 66.3%) and sulfonylurea compounds (44.7 to 39.4%), thiazolidinediones (13.6 to 3.4%) and diuretics (32.4 to 28.9%) were observed. Statistically significant decreases (all p < 0.001) of HbA1c (7.9 to 7.8%), BMI (32.5 to 32.1), eGFR (80.6 to 77.5 ml/min) and increased systolic blood pressure (130 to 132 mm Hg) were documented.

CONCLUSIONS

In the absence of glycemia treatment resistance or clinical heart failure SGLT-2 inhibitor use may not be cost effective. Enthusiasm for use of SGLT-2 inhibition should be based upon long-term cardiorenal protection rather than short-term glycemia control given limited impact upon HbA1c levels in our tertiary care type 2 diabetes population.

Expert Consensus on Telemedicine Management of Diabetes (2020 Edition)

Diabetes is a chronic disease that is very suitable for telemedicine management. Owing to the coronavirus disease 2019 (COVID-19) pandemic, telemedicine management of diabetes is particularly important. This consensus proposes 38 recommendations for key issues in telemedicine management of diabetes and provides preliminary specifications for diabetes management. It is recommended to use the most current information and communication technologies for telemanagement of patients' diet, exercise, behavior, and drug therapy. A strategy for drug therapy that is more suitable for telemedicine management of diabetes than previous ones is established. During online follow-up visits, major changes of antihyperglycemic agents must be avoided, and treatment modification should be done in a stepwise manner. Greater attention should be paid to the occurrence and prevention of hypoglycemia, in addition to educating patients about the side effects of the drugs used and encouraging them to actively report adverse drug reactions. Conditions are clarified under which online follow-up visits must be terminated and in-person visits or emergency visits must be initiated. Telemedicine can improve the management level and control rate of diabetes. The present consensus for the standardized diagnosis and treatment of diabetes can reduce the potential risks of telemedicine management, yield great benefits to patients, and reduce chronic complications and comorbidities.

Metformin, chronic nephropathy and lactic acidosis: a multi-faceted issue for the nephrologist

Metformin is currently considered a first-line therapy in type 2 diabetic patients. After issuing warnings for decades about the risks of lactic acidosis in patients with chronic nephropathy, metformin is now being re-evaluated. The most recent evidence from the literature has demonstrated both a low, acceptable risk of lactic acidosis and a series of favorable effects, which go beyond its hypoglycemic activity. Patients treated with metformin show a significant mortality reduction and lower progression towards end-stage renal disease in comparison with those treated with other hypoglycemic drugs. Concerning lactic acidosis, in the last few years it has been shown how lactic acidosis almost always developed when patients kept taking the drug in the face of a concomitant disease or situation such as sepsis, fever, diarrhea, vomiting, which reduced metformin renal clearance. Actually, clearance of metformin is mainly renal, both by glomerular filtration and tubular secretion (apparent clearance 933–1317 ml/min, half-life < 3 h). As regards treatment, in cases of lactic acidosis complicated by acute kidney injury, continuous renal replacement therapy (CRRT) plays a crucial role. Besides the elimination of metformin, CRRT  improves survival by correcting acidosis, electrolyte alterations, and maintaining fluid balance. Lactic acidosis almost always develops because of preventable drug accumulation. Therefore, prevention is a key factor. Patients should be aware that discontinuation for a limited time does not affect their health, even when it may be inappropriate, but it may avoid a serious, potentially fatal adverse event.

Where Does Metformin Stand in Modern Day Management of Type 2 Diabetes?

Metformin is the most commonly used glucose-lowering therapy (GLT) worldwide and remains the first-line therapy for newly diagnosed individuals with type 2 diabetes (T2D) in management algorithms and guidelines after the UK Prospective Diabetes Study (UKPDS) showed cardiovascular mortality benefits in the overweight population using metformin. However, the improved Major Adverse Cardiovascular Events (MACE) realised in some of the recent large cardiovascular outcomes trials (CVOTs) using sodium-glucose co-transporter 2 inhibitors (SGLT2i) and glucagon-like peptide-1 receptor agonists (GLP-1RA) have challenged metformin's position as a first-line agent in the management of T2D. Many experts now advocate revising the existing treatment algorithms to target atherosclerotic cardiovascular disease (ASCVD) and improving glycaemic control as a secondary aim. In this review article, we will revisit the major cardiovascular outcome data for metformin and include a critique of the UKPDS data. We then review additional factors that might be pertinent to metformin's status as a first-line agent and finally answer key questions when considering metformin's role in the modern-day management of T2D.

Gastrointestinal Mechanisms Underlying the Cardiovascular Effect of Metformin

Metformin, the most widely prescribed drug therapy for type 2 diabetes, has pleiotropic benefits, in addition to its capacity to lower elevated blood glucose levels, including mitigation of cardiovascular risk. The mechanisms underlying the latter remain unclear. Mechanistic studies have, hitherto, focused on the direct effects of metformin on the heart and vasculature. It is now appreciated that effects in the gastrointestinal tract are important to glucose-lowering by metformin. Gastrointestinal actions of metformin also have major implications for cardiovascular function. This review summarizes the gastrointestinal mechanisms underlying the action of metformin and their potential relevance to cardiovascular benefits.

Metformin Use and Risk of All-Cause Mortality and Cardiovascular Events in Patients With Chronic Kidney Disease-A Systematic Review and Meta-Analysis

Background

To evaluate whether metformin use assuredly alters overall all-cause death in patients with type 2 diabetes mellitus (T2DM) and chronic kidney disease (CKD).

Methods

Pubmed, Web of Science, Embase, and Cochrane Central Register of Controlled Trials were systematically searched from inception to Feb. 29, 2020 with no language restriction. All related articles comparing all-cause death of T2DM and CKD patients after metformin use (monotherapy or combination) versus non-metformin treatment were identified. Pooled risk ratios (RR) and 95% confidence intervals (CI) were computed using random-effects models regardless of the heterogeneity quantified by Cochrane χ2 and I2 statistics.

Results

Totally 13 studies (9 cohort studies [CSs], 3 subanalyses or post-hoc analyses of randomized controlled trials [RCTs], and 1 nested case-control article) involving 303,540 patients were included. Metformin-based treatments relative to any other measure displayed significantly lower risks of all-cause mortality (Pooled RRs 0.71, 95%CI 0.61 to 0.84; I2 = 79.0%) and cardiovascular events (Pooled RRs 0.76, 95%CI 0.60 to 0.97; I2 = 87.0%) in CKD patients at stage G1-3, with substantial heterogeneity. Metformin use was not significantly related with these end points in advanced CKD patients.

Conclusions

Metformin use is connected with significantly less risks of all-cause mortality and cardiovascular events in patients with T2DM and mild/moderate CKD. However, RCTs with large sample sizes are warranted in the future to assess whether these key benefits extend to later stages of CKD by dose adjustment.