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

Current type 2 diabetes guidelines: Individualized treatment and how to make the most of metformin

Evidence-based guidelines provide the premise for the delivery of quality care to preserve health and prevent disabilities and premature death. The systematic gathering of observational, mechanistic and experimental data contributes to the hierarchy of evidence used to guide clinical practice. In the field of diabetes, metformin was discovered more than 100 years ago, and with 60 years of clinical use, it has stood the test of time regarding its value in the prevention and management of type 2 diabetes. Although some guidelines have challenged the role of metformin as the first-line glucose-lowering drug, it is important to point out that the cardiovascular-renal protective effects of sodium-glucose co-transporter-2 inhibitors and glucagon-like peptide-1 receptor agonists were gathered from patients with type 2 diabetes, the majority of whom were treated with metformin. Most national, regional and international guidelines recommend metformin as a foundation therapy with emphasis on avoidance of therapeutic inertia and early attainment of multiple treatment goals. Moreover, real-world evidence has confirmed the glucose-lowering and cardiovascular-renal benefits of metformin accompanied by an extremely low risk of lactic acidosis. In patients with type 2 diabetes and advanced chronic kidney disease (estimated glomerular filtration rate 15-30 mL/min/1.73m2), metformin discontinuation was associated with an increased risk of cardiovascular-renal events compared with metformin persistence. Meanwhile, it is understood that microbiota, nutrients and metformin can interact through the gut-brain-kidney axis to modulate homeostasis of bioactive molecules, systemic inflammation and energy metabolism. While these biological changes contribute to the multisystem effects of metformin, they may also explain the gastrointestinal side effects and vitamin B12 deficiency associated with metformin intolerance. By understanding the interactions between metformin, foods and microbiota, healthcare professionals are in a better position to optimize the use of metformin and mitigate potential side effects. The United Kingdom Prospective Diabetes Study and the Da Qing Diabetes Prevention Program commenced 40 years ago provided the first evidence that type 2 diabetes is preventable and treatable. To drive real-world impact from this evidence, payors, practitioners and planners need to co-design and implement an integrated, data-driven, metformin-based programme to detect people with undiagnosed diabetes and prediabetes (intermediate hyperglycaemia), notably impaired glucose tolerance, for early intervention. The systematic data collection will create real-world evidence to bring out the best of metformin and make healthcare sustainable, affordable and accessible.

Metformin use correlated with lower risk of cardiometabolic diseases and related mortality among US cancer survivors: evidence from a nationally representative cohort study

BACKGROUND

In the USA, the prolonged effective survival of cancer population has brought significant attention to the rising risk of cardiometabolic morbidity and mortality in this population. This heightened risk underscores the urgent need for research into effective pharmacological interventions for cancer survivors. Notably, metformin, a well-known metabolic regulator with pleiotropic effects, has shown protective effects against cardiometabolic disorders in diabetic individuals. Despite these promising indications, evidence supporting its efficacy in improving cardiometabolic outcomes in cancer survivors remains scarce.

METHODS

A prospective cohort was established using a nationally representative sample of cancer survivors enrolled in the US National Health and Nutrition Examination Survey (NHANES), spanning 2003 to 2018. Outcomes were derived from patient interviews, physical examinations, and public-access linked mortality archives up to 2019. The Oxidative Balance Score was utilized to assess participants' levels of oxidative stress. To evaluate the correlations between metformin use and the risk of cardiometabolic diseases and related mortality, survival analysis of cardiometabolic mortality was performed by Cox proportional hazards model, and cross-sectional analysis of cardiometabolic diseases outcomes was performed using logistic regression models. Interaction analyses were conducted to explore the specific pharmacological mechanism of metformin.

RESULTS

Among 3995 cancer survivors (weighted population, 21,671,061, weighted mean [SE] age, 62.62 [0.33] years; 2119 [53.04%] females; 2727 [68.26%] Non-Hispanic White individuals), 448 reported metformin usage. During the follow-up period of up to 17 years (median, 6.42 years), there were 1233 recorded deaths, including 481 deaths from cardiometabolic causes. Multivariable models indicated that metformin use was associated with a lower risk of all-cause (hazard ratio [HR], 0.62; 95% confidence interval [CI], 0.47-0.81) and cardiometabolic (HR, 0.65; 95% CI, 0.44-0.97) mortality compared with metformin nonusers. Metformin use was also correlated with a lower risk of total cardiovascular disease (odds ratio [OR], 0.41; 95% CI, 0.28-0.59), stroke (OR, 0.44; 95% CI, 0.26-0.74), hypertension (OR, 0.27; 95% CI, 0.14-0.52), and coronary heart disease (OR, 0.41; 95% CI, 0.21-0.78). The observed inverse associations were consistent across subgroup analyses in four specific cancer populations identified as cardiometabolic high-risk groups. Interaction analyses suggested that metformin use as compared to non-use may counter-balance oxidative stress.

CONCLUSIONS

In this cohort study involving a nationally representative population of US cancer survivors, metformin use was significantly correlated with a lower risk of cardiometabolic diseases, all-cause mortality, and cardiometabolic mortality.

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.

Metformin and the risks of cellulitis, foot infections, and amputation in patients with type 2 diabetes

BACKGROUND

Patients with diabetes tend to have cellulitis, foot infections, and amputation. We conducted this research to compare the risks of cellulitis, foot infections, and amputation between metformin no-use and use in persons with type 2 diabetes.

METHODS

Using propensity score matching, we identified 23 234 pairs of metformin nonusers and users from the National Health Insurance Research Database of Taiwan, since January 1, 2000, to December 31, 2017. Cox proportional hazards models were adopted to examine the risks of incident cellulitis, recurrent cellulitis, foot infections, and amputation between metformin use and no-use.

RESULTS

The mean follow-up period of metformin use and no-use was 6.31 (3.93) and 5.54 (3.97) years, respectively. Compared with metformin no-use, the adjusted hazard ratio and 95% confidence interval for metformin use in cellulitis development, recurrent cellulitis, foot infections, and amputation were 1.08 (1.04-1.12), 1.33 (1.14-1.55), 1.91 (1.75-2.09), and 1.88 (1.35-2.62), respectively. The longer cumulative duration of metformin usage had association with higher risks of these outcomes than metformin no-use.

CONCLUSION

This population-based cohort study revealed that metformin use had association with significantly higher risks of incident cellulitis, recurrent cellulitis, foot infections, and amputation than metformin no-use in patients with type 2 diabetes.

Separable Microneedle for Integrated Hyperglycemia Sensing and Photothermal Responsive Metformin Release

Microdevices that offer hyperglycemia monitoring and controllable drug delivery are urgently needed for daily diabetes management. Herein, a theranostic separable double-layer microneedle (DLMN) patch consisting of a swellable GelMA supporting base layer for glycemia sensing and a phase-change material (PCM) arrowhead layer for hyperglycemia regulation has been fabricated. The Cu-TCPP(Fe)/glucose oxidase composite and 3,3',5,5'-tetramethylbenzidine coembedded in the supporting base layer permit a visible color shift at the base surface in the presence of glucose via a cascade reaction, allowing for the in situ detection of glucose in interstitial fluid. The PCM arrowhead layer is encapsulated with water monodispersity melanin nanoparticles from Sepia officinalis and metformin that is imparted with a near-infrared ray photothermal response feature, which is beneficial to the controllable release of metformin for suppression of hyperglycemia. By applying the DLMN patch to the streptozotocin-induced type 2 diabetic Sprague-Dawley rat model, the results demonstrated that it can effectively extract dermal interstitial fluid, read out glucose levels, and regulate hyperglycemia. This DLMN-integrated portable colorimetric sensor and self-regulated glucose level hold great promise for daily diabetes management.

TorS - Reframing a rational for type 2 diabetes treatment

The mammalian target of rapamycin complex 1 syndrome (Tors), paradigm implies an exhaustive cohesive disease entity driven by a hyperactive mTORC1, and which includes obesity, type 2 diabetic hyperglycemia, diabetic dyslipidemia, diabetic cardiomyopathy, diabetic nephropathy, diabetic peripheral neuropathy, hypertension, atherosclerotic cardiovascular disease, non-alcoholic fatty liver disease, some cancers, neurodegeneration, polycystic ovary syndrome, psoriasis and other. The TorS paradigm may account for the efficacy of standard-of-care treatments of type 2 diabetes (T2D) in alleviating the glycaemic and non-glycaemic diseases of TorS in T2D and non-T2D patients. The TorS paradigm may generate novel treatments for TorS diseases.

Canagliflozin + metformin ER for the treatment of type 2 diabetes: the evidence to date

INTRODUCTION

Patients with type 2 diabetes (T2D) usually show progressive deterioration in glycemic control and sequential additions of therapy are generally needed. Many new options for glucose lowering therapy have been introduced recently and it is becoming common practice to use fixed-dose combinations (FDCs) of glucose lowering agents from different classes. This article reviews the FDC of canagliflozin with metformin extended release.

AREAS COVERED

A literature search was performed to identify publications describing the efficacy and safety of canagliflozin and metformin when used separately and in combinations.

EXPERT OPINION

Canagliflozin is a sodium-glucose cotransporter-2 (SGLT2) inhibitor which has shown benefits in reducing progression of renal disease and heart failure in patients with T2D. There was an increased incidence of amputation with canagliflozin in one study, but canagliflozin results in weight loss and reduction of blood pressure which contribute to the overall benefit. Metformin has been the first line oral hypoglycemic agent for many years and is thought to have many advantages, but it should be avoided in patients with severely decreased renal function because of the risk of lactic acidosis. The combination in a single tablet given once daily should help to simplify therapy and improve medication adherence in T2D.

Unusual Extreme Leukocytosis in Metformin Overdose

We present the challenging differential diagnosis of an extreme leukocytosis noted at hospital admission of a patient with severe lactic acidosis and acute kidney injury secondary to metformin overdose. Laboratory and imaging work-up ruled out an infectious or malignant cause for severely increased leukocytes count; thus, it was established that the process of leukocyte demargination was the main cause of increased count of leukocytes. Discussion of available literature data is also presented. Our case report highlights the importance for clinicians to be aware of this possible spurious increase of leukocytes in acute non-infectious stressful conditions in order to avoid unnecessary antibiotics.

Cardiorenal diseases in type 2 diabetes mellitus: clinical trials and real-world practice

Patients with type 2 diabetes mellitus (T2DM) can have multiple comorbidities and premature mortality due to atherosclerotic cardiovascular disease, hospitalization with heart failure and/or chronic kidney disease. Traditional drugs that lower glucose, such as metformin, or that treat high blood pressure and blood levels of lipids, such as renin-angiotensin-system inhibitors and statins, have organ-protective effects in patients with T2DM. Amongst patients with T2DM treated with these traditional drugs, randomized clinical trials have confirmed the additional cardiorenal benefits of sodium-glucose co-transporter 2 inhibitors (SGLT2i), glucagon-like peptide 1 receptor agonists (GLP1RA) and nonsteroidal mineralocorticoid receptor antagonists. The cardiorenal benefits of SGLT2i extended to patients with heart failure and/or chronic kidney disease without T2DM, whereas incretin-based therapy (such as GLP1RA) reduced cardiovascular events in patients with obesity and T2DM. However, considerable care gaps exist owing to insufficient detection, therapeutic inertia and poor adherence to these life-saving medications. In this Review, we discuss the complex interconnections of cardiorenal-metabolic diseases and strategies to implement evidence-based practice. Furthermore, we consider the need to conduct clinical trials combined with registers in specific patient segments to evaluate existing and emerging therapies to address unmet needs in T2DM.

Modulating Glycolysis to Improve Cancer Therapy

Cancer cells undergo metabolic reprogramming and switch to a 'glycolysis-dominant' metabolic profile to promote their survival and meet their requirements for energy and macromolecules. This phenomenon, also known as the 'Warburg effect,' provides a survival advantage to the cancer cells and make the tumor environment more pro-cancerous. Additionally, the increased glycolytic dependence also promotes chemo/radio resistance. A similar switch to a glycolytic metabolic profile is also shown by the immune cells in the tumor microenvironment, inducing a competition between the cancer cells and the tumor-infiltrating cells over nutrients. Several recent studies have shown that targeting the enhanced glycolysis in cancer cells is a promising strategy to make them more susceptible to treatment with other conventional treatment modalities, including chemotherapy, radiotherapy, hormonal therapy, immunotherapy, and photodynamic therapy. Although several targeting strategies have been developed and several of them are in different stages of pre-clinical and clinical evaluation, there is still a lack of effective strategies to specifically target cancer cell glycolysis to improve treatment efficacy. Herein, we have reviewed our current understanding of the role of metabolic reprogramming in cancer cells and how targeting this phenomenon could be a potential strategy to improve the efficacy of conventional cancer therapy.

Elemental, fatty acid, and protein composition of appendicoliths

Appendicoliths are commonly found obstructing the lumen of the appendix at the time of appendectomy. To identify factors that might contribute to their formation we investigated the composition of appendicoliths using laser ablation inductively coupled plasma mass spectroscopy, gas chromatography, polarized light microscopy, X-ray crystallography and protein mass spectroscopy. Forty-eight elements, 32 fatty acids and 109 human proteins were identified within the appendicoliths. The most common elements found in appendicoliths are calcium and phosphorus, 11.0 ± 6.0 and 8.2 ± 4.2% weight, respectively. Palmitic acid (29.7%) and stearate (21.3%) are the most common fatty acids. Some stearate is found in crystalline form-identifiable by polarized light microscopy and confirmable by X-ray crystallography. Appendicoliths have an increased ratio of omega-6 to omega-3 fatty acids (ratio 22:1). Analysis of 16 proteins common to the appendicoliths analyzed showed antioxidant activity and neutrophil functions (e.g. activation and degranulation) to be the most highly enriched pathways. Considered together, these preliminary findings suggest oxidative stress may have a role in appendicolith formation. Further research is needed to determine how dietary factors such as omega-6 fatty acids and food additives, redox-active metals and the intestinal microbiome interact with genetic factors to predispose to appendicolith formation.

Countermeasure development against space radiation-induced gastrointestinal carcinogenesis: Current and future perspectives

A significantly higher probability of space radiation-induced gastrointestinal (GI) cancer incidence and mortality after a Mars mission has been projected using biophysical and statistical modeling approaches, and may exceed the current NASA mandated limit of less than 3% REID (risk of exposure-induced death). Since spacecraft shielding is not fully effective against heavy-ion space radiation, there is an unmet need to develop an effective medical countermeasure (MCM) strategy against heavy-ion space radiation-induced GI carcinogenesis to safeguard astronauts. In the past, we have successfully applied a GI cancer mouse model approach to understand space radiation-induced GI cancer risk and associated molecular signaling events. We have also tested several potential MCMs to safeguard astronauts during and after a prolonged space mission. In this review, we provide an updated summary of MCM testing using the GI cancer mouse model approach, lessons learned, and a perspective on the senescence signaling targeting approach for desirable protection against space radiation-induced GI carcinogenesis. Furthermore, we also discuss some of the advanced senotherapeutic candidates/combinations as a potential MCM for space radiation-induced GI carcinogenesis.

Glycolysis in tumor microenvironment as a target to improve cancer immunotherapy

Cancer cells and immune cells all undergo remarkably metabolic reprogramming during the oncogenesis and tumor immunogenic killing processes. The increased dependency on glycolysis is the most typical trait, profoundly involved in the tumor immune microenvironment and cancer immunity regulation. However, how to best utilize glycolytic targets to boost anti-tumor immunity and improve immunotherapies are not fully illustrated. In this review, we describe the glycolytic remodeling of various immune cells within the tumor microenvironment (TME) and the deleterious effects of limited nutrients and acidification derived from enhanced tumor glycolysis on immunological anti-tumor capacity. Moreover, we elucidate the underlying regulatory mechanisms of glycolytic reprogramming, including the crosstalk between metabolic pathways and immune checkpoint signaling. Importantly, we summarize the potential glycolysis-related targets that are expected to improve immunotherapy benefits. Our understanding of metabolic effects on anti-tumor immunity will be instrumental for future therapeutic regimen development.

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.