Metformin: New Preparations and Nonglycemic Benefits

The role and mechanism of VDAC1 in type 2 diabetes: An underestimated target of environmental pollutants

Type 2 diabetes (T2D) is a chronic metabolic disease that accounts for more than 90% of diabetic patients. Its main feature is hyperglycemia due to insulin resistance or insulin deficiency. With changes in diet and lifestyle habits, the incidence of T2D in adolescents has burst in recent decades. The deterioration in the exposure to the environmental pollutants further aggravates the prevalence of T2D, and consequently, it imposes a significant economic burden. Therefore, early prevention and symptomatic treatment are essential to prevent diabetic complications. Mitochondrial number and electron transport chain activity are decreased in the patients with T2D. Voltage-Dependent Anion Channel 1 (VDAC1), as a crucial channel protein on the outer membrane of mitochondria, regulates signal transduction between mitochondria and other cellular components, participating in various biological processes. When VDAC1 exists in oligomeric form, it additionally facilitates the entry and exit of macromolecules into and from mitochondria, modulating insulin secretion. We summarize and highlight the interplay between VDAC1 and T2D, especially in the environmental pollutants-related T2D, shed light on the potential therapeutic implications of targeting VDAC1 monomers and oligomers, providing a new possible target for the treatment of T2D.

Protein Tyrosine Phosphatase 1B (PTP1B): A Comprehensive Review of Its Role in Pathogenesis of Human Diseases

Overexpression of protein tyrosine phosphatase 1B (PTP1B) disrupts signaling pathways and results in numerous human diseases. In particular, its involvement has been well documented in the pathogenesis of metabolic disorders (diabetes mellitus type I and type II, fatty liver disease, and obesity); neurodegenerative diseases (Alzheimer's disease, Parkinson's disease); major depressive disorder; calcific aortic valve disease; as well as several cancer types. Given this multitude of therapeutic applications, shortly after identification of PTP1B and its role, the pursuit to introduce safe and selective enzyme inhibitors began. Regrettably, efforts undertaken so far have proved unsuccessful, since all proposed PTP1B inhibitors failed, or are yet to complete, clinical trials. Intending to aid introduction of the new generation of PTP1B inhibitors, this work collects and organizes the current state of the art. In particular, this review intends to elucidate intricate relations between numerous diseases associated with the overexpression of PTP1B, as we believe that it is of the utmost significance to establish and follow a brand-new holistic approach in the treatment of interconnected conditions. With this in mind, this comprehensive review aims to validate the PTP1B enzyme as a promising molecular target, and to reinforce future research in this direction.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Advancements in pharmacotherapy options for treating diabetes ‎in children and adolescents

INTRODUCTION

This study compares diabetes management between pediatric and adult patients and identifies treatment challenges and gaps.

AREAS COVERED

We searched PubMed and Clinicaltrails.gov databases for studies published from 2001 to 2023 on diabetes management in different age groups.

EXPERT OPINION

Research shows children have lower insulin sensitivity, clearance, and β cell function than adults. The US FDA only allows insulin, metformin, and liraglutide as antidiabetic medication options for children. However, some off-label drugs, like meglitinides, sulfonylureas, and alogliptin, have demonstrated positive results in treating certain types of diabetes caused by gene mutations. It's crucial to adopt personalized and precise approaches to managing diabetes in pediatrics, which vary from those used for adult patients. New studies support the classification of type 2 diabetes into several subtypes based on age, BMI, glycemia, homeostasis model estimates, varying insulin resistance, ‎different rates of complications‎, and islet ‎autoantibodies. With this insight, prevention, treatment, and precision medicine of diabetes might be changed. More research is necessary to assess the safety and efficacy of different antidiabetic drugs and improve diabetes treatment for children and adolescents.

Aerobic exercise and metformin on intermuscular adipose tissue (IMAT): insights from multimodal MRI and histological changes in prediabetic rats

BACKGROUND

Physical exercise is the first-line intervention for prediabetes, and metformin is the most widely used oral insulin-sensitizing agent. Moreover, intermuscular adipose tissue (IMAT) directly affects insulin resistance by helping maintain glucose homeostasis. Here, we evaluated the effects of moderate aerobic exercise and/or metformin on histological IMAT parameters in non-streptozotocin-induced prediabetes.

METHODS

Male Wistar rats with prediabetes fed a high-fat diet and high-sugar drinks were randomly assigned to high-fat diet (PRE), metformin (MET), moderate aerobic exercise (EXE), combined therapy (EMC), or EMC + compound-c (EMA) groups for 4 weeks. Multimodal magnetic resonance imaging (MRI) was then performed, and tissue-specific inflammation and energy and lipid metabolism were evaluated in IMAT.

RESULTS

The EXE group had lower inflammatory factor levels, lipid metabolism, and mitochondrial oxidative stress, and shorter IMAT adipocyte diameters than the MET group. The MET group exhibited lower IL-1β and Plin5 expression than the PRE group. Furthermore, the IMAT of the EMC group had lower TNF-α and phosphorylated NF-κB levels and higher GLUT1 and GLUT4 expression than the PRE group. Multimodal MRI revealed significant changes in transverse-relaxation time 2, apparent diffusion coefficient, and fractional anisotropy values in the IMAT and muscles, as well as lower IMAT% values in the EXE and EMC groups than in the MET and PRE groups.

CONCLUSION

Moderate aerobic exercise training can effectively improve IMAT function and structure via the AMP-activated protein kinase pathway in prediabetes. Combining metformin with moderate aerobic exercise might elicit modest synergy, and metformin does not counterbalance the beneficial effects of exercise.

Insights Into Metformin XR Pharmacotherapy Knowledge Among Community Pharmacists: A Cross-Sectional Study

Background

There is a little knowledge on the extent to which healthcare providers understand and accept the professional recommendations and appropriate dosing strategy regarding metformin XR.

Objectives

To evaluate UAE community pharmacists' knowledge, attitude, and practices (KAP) concerning metformin XR.

Methods

This is a cross-sectional research study conducted amongst licensed community pharmacists. The survey took place via a questionnaire and physical interviews were held. The survey used in this study included questions on demographics and questions on the participants' attitudes, knowledge and practices concerning metformin XR. The factors influencing KAP regarding metformin XR were examined via simple logistic regression analysis.

Results

Threehundred fifty-three (n = 353) participants were recruited in the study. Independent pharmacies constituted 57.5% of this study sample and 42.5% were chain pharmacies. The average knowledge score about metformin XR tablets was 42.5% with a confidence interval (CI) of 95% [37.3%, 47.4]. Better knowledge scores on metformin XR tablets was observed in respondents aged ⩾40 years (OR 2.97, 95% CI 1.63-5.4), having greater than 10 years in terms of experience (OR 2.28; 95% CI 1.25-4.16) and pharmacist graduated from Regional or international universities (OR 2.08; 95% CI 1.34-3.24). About 78% (n = 275) of the participants believed that metformin XR tablets have better efficacy and 63.2% (n = 233) indicated that metformin IR was associated with greater adverse effects.

Conclusion

This study demonstrated a distinct gap in knowledge, attitude and practice pertaining to metformin XR among community pharmacists in the UAE. The community pharmacists need to enhance their practice by receiving accurate and reliable data to support their decision-making on the prescribing of metformin XR. The implementation of novel guidelines and evidence dissemination strategies may help bridge this gap.

The association between circulatory, local pancreatic PCSK9 and type 2 diabetes mellitus: The effects of antidiabetic drugs on PCSK9

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a potent modulator of cholesterol metabolism and plays a crucial role in the normal functioning of pancreatic islets and the progression of diabetes. Islet autocrine PCSK9 deficiency can lead to the enrichment of low-density lipoprotein (LDL) receptor (LDLR) and excessive LDL cholesterol (LDL-C) uptake, subsequently impairing the insulin secretion in β-cells. Circulatory PCSK9 levels are primarily attributed to hepatocyte secretion. Notably, anti-PCSK9 strategies proposed for individuals with hypercholesterolemia chiefly target liver-derived PCSK9; however, these anti-PCSK9 strategies have been associated with the risk of new-onset diabetes mellitus (NODM). In the current review, we highlight a new direction in PCSK9 inhibition therapy strategies: screening candidates for anti-PCSK9 from the drugs used in type 2 diabetes mellitus (T2DM) treatment. We explored the association between circulating, local pancreatic PCSK9 and T2DM, as well as the relationship between PCSK9 monoclonal antibodies and NODM. We discussed the emergence of artificial and natural drugs in recent years, exhibiting dual benefits of antidiabetic activity and PCSK9 reduction, confirming that the diverse effects of these drugs may potentially impact the progression of diabetes and associated disorders, thereby introducing novel avenues and methodologies to enhance disease prognosis.

Current Treatments for Diabetic Macular Edema

Diabetic retinopathy is a major retinal disorder and a leading cause of blindness. Diabetic macular edema (DME) is an ocular complication in patients with diabetes, and it can impair vision significantly. DME is a disorder of the neurovascular system, and it causes obstructions of the retinal capillaries, damage of the blood vessels, and hyperpermeability due to the expression and action of vascular endothelial growth factor (VEGF). These changes result in hemorrhages and leakages of the serous components of blood that result in failures of the neurovascular units (NVUs). Persistent edema of the retina around the macula causes damage to the neural cells that constitute the NVUs resulting in diabetic neuropathy of the retina and a reduction in vision quality. The macular edema and NVU disorders can be monitored by optical coherence tomography (OCT). Neuronal cell death and axonal degeneration are irreversible, and their development can result in permanent visual loss. Treating the edema before these changes are detected in the OCT images is necessary for neuroprotection and maintenance of good vision. This review describes the effective treatments for the macular edema that are therefore neuroprotective.

Nephroprotective Properties of Antidiabetic Drugs

Chronic kidney disease (CKD) is associated with increased morbidity and mortality, especially from cardiovascular (CV) causes, and especially in people with diabetes mellitus (DM). Already the presence of DM increases CV risk and potentiates the risk of CKD. Therefore, besides glycemic control, prevention and treatment of CKD to slow its progression are of clinical importance. A significant nephroprotective effect of novel antidiabetic drugs, namely sodium-glucose cotransporter 2 inhibitors (SGLT2-I) and glucagon-like peptide 1 receptor agonists (GLP1-RA), has been shown on top of their glucose-lowering effects and was confirmed in cardiovascular outcome trials. GLP1-RA mainly reduced the risk of macroalbuminuria, whereas SGLT2-I were also associated with a lower risk of declining glomerular filtration rate (GFR) over time. The nephroprotective effects of SGLT2-I are also evident in people without DM. According to current guidelines, SGLT2-I and/or GLP1-RA are recommended for people with DM who have chronic kidney disease and/or increased cardiovascular risk. However, other antidiabetic drugs offer nephroprotective properties, which will also be discussed in this review.

Integrative analyses of biomarkers and pathways for metformin reversing cisplatin resistance in head and neck squamous cell carcinoma cells

OBJECTIVES

In this study, transcriptome sequencing were performed to elucidate the molecular mechanism by which metformin inhibits head and neck squamous cell carcinoma (HNSCC) cells progression and sensitizes HNSCC cells to chemotherapy. We aimed to propose a novel chemotherapeutic approach with high efficacy and few side effects and provide a new strategy for HNSCC treatment.

DESIGN

The effects of metformin on the biological behaviors of HNSCC cells were validated by CCK8 cell proliferation assays, would healing assays and flow cytometric apoptosis assays. The appropriate metformin concentrations for the experimental pretreatment of HNSCC cells were selected based on experimental results, and the treated cells were subjected to transcriptome sequencing. After bioinformatics analysis and intersection with a post-chemotherapy resistance dataset from the GEO database numbered GSE102787, the genes were identified and used to predict potential metformin targets after functional enrichment analysis.

RESULTS

Metformin significantly inhibited the proliferation and migration and induced the apoptosis of Cal27 and FaDu cells. A total of 284 genes that are potentially targeted by metformin during HNSCC cell sensitization were identified by bioinformatics, and ten hub genes with high connectivity were selected. In particular, Fen1 overexpression was associated with poor prognosis in HNSCC patients.

CONCLUSIONS

Our study demonstrates that Fen1 is overexpressed in HNSCC tissues compared with normal tissues and that Fen1 overexpression is a poor prognostic factor in HNSCC patients. Metformin enhances the ability of cisplatin to inhibit HNSCC progression. Further studies are needed to explore the therapeutic value of Fen1 in HNSCC.

The Role of Gut Microbiota in High-Fat-Diet-Induced Diabetes: Lessons from Animal Models and Humans

The number of diabetes mellitus patients is increasing rapidly worldwide. Diet and nutrition are strongly believed to play a significant role in the development of diabetes mellitus. However, the specific dietary factors and detailed mechanisms of its development have not been clearly elucidated. Increasing evidence indicates the intestinal microbiota is becoming abundantly apparent in the progression and prevention of insulin resistance in diabetes. Differences in gut microbiota composition, particularly butyrate-producing bacteria, have been observed in preclinical animal models as well as human patients compared to healthy controls. Gut microbiota dysbiosis may disrupt intestinal barrier functions and alter host metabolic pathways, directly or indirectly relating to insulin resistance. In this article, we focus on dietary fat, diabetes, and gut microbiome characterization. The promising probiotic and prebiotic approaches to diabetes, by favorably modifying the composition of the gut microbial community, warrant further investigation through well-designed human clinical studies.

GBM Cells Exhibit Susceptibility to Metformin Treatment According to TLR4 Pathway Activation and Metabolic and Antioxidant Status

Glioblastoma (GBM) is an aggressive brain cancer associated with poor overall survival. The metabolic status and tumor microenvironment of GBM cells have been targeted to improve therapeutic strategies. TLR4 is an important innate immune receptor capable of recognizing pathogens and danger-associated molecules. We have previously demonstrated the presence of TLR4 in GBM tumors and the decreased viability of the GBM tumor cell line after lipopolysaccharide (LPS) (TLR4 agonist) stimulation. In the present study, metformin (MET) treatment, used in combination with temozolomide (TMZ) in two GBM cell lines (U87MG and A172) and stimulated with LPS was analyzed. MET is a drug widely used for the treatment of diabetes and has been repurposed for cancer treatment owing to its anti-proliferative and anti-inflammatory actions. The aim of the study was to investigate MET and LPS treatment in two GBM cell lines with different metabolic statuses. MET treatment led to mitochondrial respiration blunting and oxidative stress with superoxide production in both cell lines, more markedly in U87MG cells. Decreased cell viability after MET + TMZ and MET + LPS + TMZ treatment was observed in both cell lines. U87MG cells exhibited apoptosis after MET + LPS + TMZ treatment, promoting increased ER stress, unfolded protein response, and BLC2 downregulation. LPS stimulation of U87MG cells led to upregulation of SOD2 and genes related to the TLR4 signaling pathway, including IL1B and CXCL8. A172 cells attained upregulated antioxidant gene expression, particularly SOD1, TXN and PRDX1-5, while MET treatment led to cell-cycle arrest. In silico analysis of the TCGA-GBM-RNASeq dataset indicated that the glycolytic plurimetabolic (GPM)-GBM subtype had a transcriptomic profile which overlapped with U87MG cells, suggesting GBM cases exhibiting this metabolic background with an activated inflammatory TLR4 pathway may respond to MET treatment. For cases with upregulated CXCL8, coding for IL8 (a pro-angiogenic factor), combination treatment with an IL8 inhibitor may improve tumor growth control. The A172 cell line corresponded to the mitochondrial (MTC)-GBM subtype, where MET plus an antioxidant inhibitor, such as anti-SOD1, may be indicated as a combinatory therapy.

Biomechanical forces and signals operating in the ovary during folliculogenesis and their dysregulation: implications for fertility

BACKGROUND

Folliculogenesis occurs in the highly dynamic environment of the ovary. Follicle cyclic recruitment, neo-angiogenesis, spatial displacement, follicle atresia and ovulation stand out as major events resulting from the interplay between mechanical forces and molecular signals. Morphological and functional changes to the growing follicle and to the surrounding tissue are required to produce oocytes capable of supporting preimplantation development to the blastocyst stage.

OBJECTIVE AND RATIONALE

This review will summarize the ovarian morphological and functional context that contributes to follicle recruitment, growth and ovulation, as well as to the acquisition of oocyte developmental competence. We will describe the changes occurring during folliculogenesis to the ovarian extracellular matrix (ECM) and to the vasculature, their influence on the mechanical properties of the ovarian tissue, and, in turn, their influence on the regulation of signal transduction. Also, we will outline how their dysregulation might be associated with pathologies such as polycystic ovary syndrome (PCOS), endometriosis or premature ovarian insufficiency (POI). Finally, for each of these three pathologies, we will highlight therapeutic strategies attempting to correct the altered biomechanical context in order to restore fertility.

SEARCH METHODS

For each area discussed, a systematic bibliographical search was performed, without temporal limits, using PubMed Central, Web of Science and Scopus search engines employing the keywords extracellular matrix, mechanobiology, biomechanics, vasculature, angiogenesis or signalling pathway in combination with: ovary, oogenesis, oocyte, folliculogenesis, ovarian follicle, theca, granulosa, cumulus, follicular fluid, corpus luteum, meiosis, oocyte developmental competence, preimplantation, polycystic ovary syndrome, premature ovarian insufficiency or endometriosis.

OUTCOMES

Through search engines queries, we yielded a total of 37 368 papers that were further selected based on our focus on mammals and, specifically, on rodents, bovine, equine, ovine, primates and human, and also were trimmed around each specific topic of the review. After the elimination of duplicates, this selection process resulted in 628 papers, of which 287 were cited in the manuscript. Among these, 89.2% were published in the past 22 years, while the remaining 8.0%, 2.4% or 0.3% were published during the 1990s, 1980s or before, respectively. During folliculogenesis, changes occur to the ovarian ECM composition and organization that, together with vasculature modelling around the growing follicle, are aimed to sustain its recruitment and growth, and the maturation of the enclosed oocyte. These events define the scenario in which mechanical forces are key to the regulation of cascades of molecular signals. Alterations to this context determine impaired folliculogenesis and decreased oocyte developmental potential, as observed in pathological conditions which are causes of infertility, such as PCOS, endometriosis or POI.

WIDER IMPLICATIONS

The knowledge of these mechanisms and the rules that govern them lay a sound basis to explain how follicles recruitment and growth are modulated, and stimulate insights to develop, in clinical practice, strategies to improve follicular recruitment and oocyte competence, particularly for pathologies like PCOS, endometriosis and POI.

Metformin: A Promising Antidiabetic Medication for Cancer Treatment

Metformin is a widely used drug in patients with type 2 diabetes mellitus. Metformin inhibits hepatic gluconeogenesis and increases glucose utilization in peripheral tissues. In recent years, several studies have shown that metformin is a potential therapeutic agent against cancer, alone or combined with other anticancer treatments. Metformin mainly activates the AMPK complex and regulates intracellular energy status, inhibiting the mitochondrial respiratory chain complex I and reducing the production of reactive oxygen species. Other anticancer targets of metformin are specific transcription factors inhibiting cell proliferation, promoting apoptosis and reducing drug resistance. In addition, metformin modulates tumor cells' response to anticancer treatments, favoring the activity of T cells. In diabetic patients, metformin reduces the occurrence of cancer and improves the prognosis and efficacy of anticancer treatments. In this review, we provided a comprehensive perspective of metformin as an anticancer drug.

Preparing for Colonoscopy in People with Diabetes: A Review with Suggestions for Clinical Practice

People with diabetes have an increased risk of adverse events during the peri-colonoscopy period, including hypoglycemia, lactic acidosis, diabetic ketoacidosis and acute kidney injury. This is secondary to inadequate dietary modification, the bowel preparation and antihyperglycemic agent modification. With the availability of many new diabetes agents, endoscopists need updated guidance. This review of current literature provides a practical approach to antihyperglycemic agent modification in the context of colonoscopy preparation, as well as guidelines on dietary changes, the bowel preparation itself and glucose monitoring.

Design and optimization of metformin-loaded solid lipid nanoparticles for neuroprotective effects in a rat model of diffuse traumatic brain injury: A biochemical, behavioral, and histological study

BACKGROUND AND PURPOSE

Following traumatic brain injury, inflammation, mitochondrial dysfunction, oxidative stress, ischemia, and energy crisis can cause mortality or long-term morbidity. As an activator of AMP-activated protein kinase, metformin reduces the secondary injuries of traumatic brain injury by compensating for the lack of energy in damaged cells. But the blood-brain barrier prevents a hydrophilic drug such as metformin from penetrating the brain tissue. Solid lipid nanoparticles with their lipid nature can cross the blood-brain barrier and solve this challenge. so This study aimed to investigate the effect of metformin-loaded lipid nanoparticles (NanoMet) for drug delivery to the brain and reduce complications from traumatic brain injury.

METHOD

Different formulations of NanoMet were designed by Box-Behnken, and after formulation, particle size, zeta potential, and entrapment efficiency were investigated. For in vivo study, Male rats were divided into eight groups, and except for the intact and sham groups, the other groups underwent brain trauma by the Marmarou method. After the intervention, the Veterinary Coma Scale, Vestibular Motor function, blood-brain barrier integrity, cerebral edema, level of inflammatory cytokines, and histopathology of brain tissue were assessed.

RESULTS

The optimal formula had a size of 282.2 ± 9.05 nm, a zeta potential of -1.65 ± 0.33 mV, and entrapment efficiency of 60.61 ± 6.09% which released the drug in 1400 min. Concentrations of 5 and 10 mg/kg of this formula improved the consequences of trauma.

CONCLUSION

This study showed that nanoparticles could help target drug delivery to the brain and apply the desired result.

Pharmacotherapy of type 2 diabetes: An update and future directions

Type 2 diabetes (T2D) is a widely prevalent disease with substantial economic and social impact for which multiple conventional and novel pharmacotherapies are currently available; however, the landscape of T2D treatment is constantly changing as new therapies emerge and the understanding of currently available agents deepens. This review aims to provide an updated summary of the pharmacotherapeutic approach to T2D. Each class of agents is presented by mechanism of action, details of administration, side effect profile, cost, and use in certain populations including heart failure, non-alcoholic fatty liver disease, obesity, chronic kidney disease, and older individuals. We also review targets of novel therapeutic T2D agent development. Finally, we outline an up-to-date treatment approach that starts with identification of an individualized goal for glycemic control then selection, initiation, and further intensification of a personalized therapeutic plan for T2D.

Metformin therapy as a strategy to compensate anti-VEGF resistance in patients with diabetic macular edema

Diabetic macular edema (DME) is the complication of diabetic retinopathy, the leading cause of vision loss among diabetic patients. Metformin is the main antidiabetic treatment. It is preferable for its great anti-angiogenic and anti-inflammatory effects. Anti-vascular endothelial growth factor (VEGF) therapy is the preferable treatment for DME despite its lack of convincing results in some patients. To assess whether the combination of metformin and anti-VEGF drugs may decrease the risk of anti-VEGF resistance among DME patients. We included DME patients with a central retinal thickness (CRT) ≥ 250 μm who consecutively underwent at least 3 anti-VEGF therapies from January 1, 2020, to December 30, 2021. Anti-VEGF resistance was defined as persistent macular edema with decreased CRT ≤ 25% after 3 anti-VEGF injections. 109 patients were considered for this research, of whom 65 (59.6%) were resistant to anti-VEGF therapy. The mean CRT of the non-metformin group decreased from 344.88 ± 129.48 to 318.29 ± 123.23 (20.85%) and from 415.64 ± 144.26 to 277.11 ± 99.25 (31.51%) (P = .031) in the metformin group. Moreover, the metformin group had fewer resistant patients than the non-metformin, 24 (45.3%) versus 41 (73.2%). Furthermore, a considerable gain in visual acuity was observed in both groups, with a BCVA gain of 40.41% in the metformin group and 39.9% in the non-metformin group. Metformin may be combined with an anti-VEGF drug to minimize the risk of anti-VEGF resistance among DME patients. Moreover, it can serve to design effective therapeutic deliveries.

A Randomized Study on the Effect of Metformin Combined with Intensive-Exercise Diet Therapy on Glucose and Lipid Metabolism and Islet Function in Patients with Renal Cell Carcinoma and Diabetes

Objective. To evaluate the effect of metformin combined with intensive-exercise diet therapy on glucose and lipid metabolism and islet function in diabetes patients with localized renal cell carcinoma after laparoscopic resection. Methods. A total of 120 renal cancer patients with diabetes mellitus treated in the oncology department of our hospital from January 2018 to December 2020 were recruited and assigned via random number table method at a ratio of 1 : 1 to receive either metformin (control group) or metformin plus intensive exercise diet therapy (study group) after laparoscopic nephrectomy. Outcome measures included glucose and lipid metabolism, pancreatic islet function, lifestyle, clinical efficacy, and adverse reactions. Results. After the intervention, the fasting blood glucose (FBG), 2 h postprandial blood glucose (PBG), glycosylated hemoglobin (HbA1c), triglyceride (TG), total cholesterol (TC), and low-density lipoprotein cholesterol (LDL-C) of the two groups of patients decreased significantly, and the study group had significantly lower results. After treatment, the two groups had elevated levels of high-density lipoprotein cholesterol (HDL-C), fasting serum insulin (FINS), and homeostasis model assessment of β-cell function (HOMA-β), and higher results were obtained in the study group ( $P<0.05$ ). After the intervention, the study group showed higher results of health promoting lifestyle profile-II (HPLP-II) and a 12-month progression-free survival rate than the control group. There were no significant differences in the incidence of adverse reactions between the two groups. Conclusion. Metformin combined with intensive-exercise diet therapy significantly improves the glucose and lipid metabolism and islet function of renal cancer patients with diabetes and effectively enhances the 12-month progression-free survival. Further trials are, however, required prior to clinical application.

Short-Term Metformin Treatment Enriches Bacteroides dorei in an Obese Liver Steatosis Zucker Rat Model

Obesity is the leading cause of health-related diseases in the United States and World. Previously, we reported that obesity can change gut microbiota using the Zucker rat model. Metformin is an oral anti-hyperglycemic agent approved by the FDA to treat type 2 diabetes (T2D) in adults and children older than 10 years of age. The correlation of short-term metformin treatment and specific alterations to the gut microbiota in obese models is less known. Short-term metformin has been shown to reduce liver steatosis. Here we investigate the effects of short-term metformin treatment on population of gut microbiota profile in an obese rat model. Five week old obese (n = 12) female Zucker rats after 1 week of acclimation, received AIN-93 G diet for 8 weeks and then rats were randomly assigned into two groups (6 rats/group): (1) obese without metformin (ObC), or (2) obese with metformin (ObMet). Metformin was mixed with AIN-93G diet at 1,000 mg/kg of diet. Rats were weighed twice per week. All rats were sacrificed at the end of metformin treatment at 10 weeks and fecal samples were collected and kept at -80°C. Total microbial DNA was collected directly from the fecal samples used for shotgun-metagenomics sequencing and subsequently analyzed using MetaPlAn and HUMAnN. After stringent data filtering and quality control we found significant differences (p = 0.0007) in beta diversity (Aitchison distances) between the ObC vs. ObMet groups. Supervised and unsupervised analysis of the log-ratios Bacteroides dorei and B. massiliensis vs. all other Bacteroides spp., revealed that B. dorei and B. massiliensis were enriched in the ObMet group, while the remaining Bacteroides spp. where enriched in the ObC group (p = 0.002). The contributional diversity of pathways is also significantly associated by treatment group (p = 0.008). In summary, in the obese Zucker rat model, short-term metformin treatment changes the gut microbiota profile, particularly altering the composition Bacteroides spp. between ObC and ObMet.

Metformin alleviates chronic obstructive pulmonary disease and cigarette smoke extract-induced glucocorticoid resistance by activating the nuclear factor E2-related factor 2/heme oxygenase-1 signaling pathway

Chronic obstructive pulmonary disease (COPD) is an important healthcare problem worldwide. Often, glucocorticoid (GC) resistance develops during COPD treatment. As a classic hypoglycemic drug, metformin (MET) can be used as a treatment strategy for COPD due to its anti-inflammatory and antioxidant effects, but its specific mechanism of action is not known. We aimed to clarify the role of MET on COPD and cigarette smoke extract (CSE)-induced GC resistance. Through establishment of a COPD model in rats, we found that MET could improve lung function, reduce pathological injury, as well as reduce the level of inflammation and oxidative stress in COPD, and upregulate expression of nuclear factor E2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1), multidrug resistance protein 1 (MRP1), and histone deacetylase 2 (HDAC2). By establishing a model of GC resistance in human bronchial epithelial cells stimulated by CSE, we found that MET reduced secretion of interleukin-8, and could upregulate expression of Nrf2, HO-1, MRP1, and HDAC2. MET could also increase the inhibition of MRP1 efflux by MK571 significantly, and increase expression of HDAC2 mRNA and protein. In conclusion, MET may upregulate MRP1 expression by activating the Nrf2/HO-1 signaling pathway, and then regulate expression of HDAC2 protein to reduce GC resistance.

Brain Cancer Drug Discovery: Clinical Trials, Drug Classes, Targets, and Combinatorial Therapies

Brain cancer is a formidable challenge for drug development, and drugs derived from many cutting-edge technologies are being tested in clinical trials. We manually characterized 981 clinical trials on brain tumors that were registered in ClinicalTrials.gov from 2010 to 2020. We identified 582 unique therapeutic entities targeting 581 unique drug targets and 557 unique treatment combinations involving drugs. We performed the classification of both the drugs and drug targets based on pharmacological and structural classifications. Our analysis demonstrates a large diversity of agents and targets. Currently, we identified 32 different pharmacological directions for therapies that are based on 42 structural classes of agents. Our analysis shows that kinase inhibitors, chemotherapeutic agents, and cancer vaccines are the three most common classes of agents identified in trials. Agents in clinical trials demonstrated uneven distribution in combination approaches; chemotherapy agents, proteasome inhibitors, and immune modulators frequently appeared in combinations, whereas kinase inhibitors, modified immune effector cells did not as was shown by combination networks and descriptive statistics. This analysis provides an extensive overview of the drug discovery field in brain cancer, shifts that have been happening in recent years, and challenges that are likely to come. SIGNIFICANCE STATEMENT: This review provides comprehensive quantitative analysis and discussion of the brain cancer drug discovery field, including classification of drug, targets, and therapies.

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

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

Serum levels of inflammatory markers and HbA1c in patients with type 2 diabetes and apical periodontitis: Preliminary findings

This pilot study assessed the glycaemic control and the serum levels of inflammatory mediators in type 2 diabetes (T2DM) patients with apical periodontitis (AP). Thirty individuals were divided into four groups: Healthy (H); with AP (AP); with T2DM (T2DM); and with T2DM and AP (T2DM-AP). Demographic and pharmacological data were registered. The body mass index (BMI) and the levels of glycated haemoglobin (HbA1c) and IL-1β, IL-6, IL-10, CCL3 and CCL4 were evaluated. AP areas were determined radiographically. Mean age was 64 ± 12 years, with 63% females. Most T2DM patients were under treatment with metformin and antihypertensives. BMI and H1bAc were significantly higher in T2DM patients in relation to H and AP groups. The AP areas were larger in the T2DM-AP group, compared with the AP group. These preliminary findings suggest no influence of AP on glycaemic control or inflammatory levels amongst T2DM patients, although T2DM increased the AP severity.

Metformin attenuates the epithelial-mesenchymal transition of lens epithelial cells through the AMPK/TGF-β/Smad2/3 signalling pathway

Posterior capsule opacification (PCO) is a common ocular fibrosis disease related to the epithelial-mesenchymal transition (EMT) of human lens epithelial cells (HLECs). However, safe and effective drugs that prevent or treat PCO are lacking. Metformin (Mtf) has been used to treat fibrosis-related diseases affecting many organs and tissues, but its effect on ocular fibrosis-related diseases is unclear. We investigated whether Mtf can inhibit EMT and fibrosis in HLECs to prevent and treat PCO and elucidated the potential molecular mechanism. Here, we established an HLEC model of TGF-β-induced EMT and found that 400 μM Mtf inhibited vertical and lateral migration and EMT-related gene and protein expression in HLECs. Smad2/3 are downstream molecules of TGF-β that enter the nucleus to regulate EMT-related gene expression during the occurrence and development of PCO. We revealed that Mtf suppressed TGF-β-induced Smad2/3 phosphorylation and nuclear translocation. Mtf induces AMP-activated protein kinase (AMPK) phosphorylation. In this study, we found that Mtf induced the activation of AMPK phosphorylation in HLECs. To further explore the mechanism of Mtf, we pretreated HLECs with Compound C (an AMPK inhibitor) to repeat the above experiments and found that Compound C abolished the inhibitory effect of Mtf on HLEC EMT and the TGF-β/Smad2/3 signalling pathway. Thus, Mtf targets AMPK phosphorylation to inhibit the TGF-β/Smad2/3 signalling pathway and prevent HLEC EMT. Notably, we first illustrated the AMPK/TGF-β/Smad2/3 signalling pathway in HLECs, which may provide a new therapeutic strategy for PCO.

Clinical Characteristics and Prognostic Analysis of Patients With Pulmonary Tuberculosis and Type 2 Diabetes Comorbidity in China: A Retrospective Analysis

Background: Tuberculosis (TB) is one of the leading communicable diseases, with significant morbidity and mortality. Diabetes can increase the risk of developing TB and the related adverse outcomes. This study retrospectively analyzed the clinical characteristics and prognosis of patients with pulmonary TB and type 2 diabetes comorbidity.

Methods: About 282 cases with pulmonary TB and type 2 diabetes comorbidity were identified from West China Hospital between January 1, 2010, and December 31, 2016, and were followed up for at least 3 years. We further used Kaplan–Meier methods and COX regression analysis to identify the influence factors for all-cause death.

Results: Compared to the survival patients, patients who died were older, exhibited significantly lower albumin and hemoglobin levels, but higher Charlson Comorbidity Index (CCI) score at admission, and had a lower usage rate of metformin. The all-cause mortality rates at 1 and 5 years were 5.67 and 20.59%, separately. For 1-year all-cause death, higher albumin level (HR = 0.90, 95% CI: 0.81–0.99) was the independently protective factor, but older age (HR = 1.07, 95% CI: 1.01–1.13) and CCI score ≥3 (HR = 6.77, 95% CI: 1.40–32.69) were the independent risk factors. For long-term all-cause death, higher albumin level (HR = 0.94, 95% CI: 0.88–1.00), the use of metformin (HR = 0.21, 95% CI: 0.07–0.59), insulin (HR = 0.27, 95% CI: 0.10–0.74), or sulfonylureas (HR = 0.23, 95% CI: 0.07–0.74) were the independently protective factors, but older age (HR = 1.03, 95% CI: 1.00–1.07) and CCI score ≥3 (HR = 7.15, 95% CI: 2.56–19.92) were the independent risk factors.

Conclusions: The lower albumin level, older age, and CCI score ≥3 were predictors of all-cause death in patients with pulmonary TB and type 2 diabetes comorbidity. In the long run, patients who use metformin, insulin, or sulfonylureas as hypoglycemic agents may have a lower incidence of death.

Association of metformin use on metabolic acidosis in diabetic patients with chronic hepatitis B-related cirrhosis and renal impairment

BACKGROUND AND AIMS

Metformin is an oral anti-hyperglycemic recommended by the American Diabetes Association (ADA) as a preferred initial pharmacologic agent for type 2 diabetes. Metabolic acidosis is a rare yet severe side effect of it. We examined the association of metformin use and dosage on the risk of metabolic acidosis in diabetic patients with different degrees of chronic hepatitis B (CHB)-related cirrhosis and chronic kidney disease (CKD).

METHODS

Metabolic acidosis was defined by blood pH ≤7.35, together with lactate >5 mmol/L or arterial bicarbonate ≤18 mmol/L or venous bicarbonate ≤21 mmol/L, and/or diagnosis codes. Child-Pugh class and CKD stage were included in the model as time-dependent covariates. Age, gender, comorbidities, and use of relevant medications were adjusted as covariates. Maximum daily dose of metformin was classified into ≤1000 mg and >1000 mg.

RESULTS

We identified 4431 diabetic patients with CHB-related cirrhosis between 2000 and 2017 from a territory-wide database in Hong Kong. The risk of metabolic acidosis increased with Child-Pugh class B and C cirrhosis regardless of CKD stage (adjusted subdistribution hazard ratio [aSHR] ranged from 3.50 to 86.16). Metformin use was associated with a higher risk in patients with Child-Pugh class B or C cirrhosis and stage 3A CKD or above (aSHR ranged from 1.55 to 2.46). In stage 4/5 CKD, a daily dose of metformin ≤1000 mg was still associated with a higher risk of metabolic acidosis regardless of the severity of cirrhosis (aSHR ranged from 2.45 to 3.92).

CONCLUSION

In conclusion, patients with Child-Pugh class B cirrhosis or above were at a higher risk of metabolic acidosis. Metformin further increased the risk in patients with Child-Pugh class B cirrhosis or above and stage 3A CKD or above. Dose adjustment in stage 4/5 CKD did not reduce the risk of metabolic acidosis.

Metformin extended-release versus metformin immediate-release for adults with type 2 diabetes mellitus: A systematic review and meta-analysis of randomized controlled trials

AIM

To compare the efficacy and tolerability of metformin extended-release (MXR) and the conventional metformin immediate-release (MIR) formulations in adults with type 2 diabetes mellitus (T2DM) METHODS: PubMed, the Cochrane Library, ClinicalTrials.gov and other sources were searched until 19 March 2021 for randomized controlled trials (RCTs) that compared equal daily doses of MXR and MIR in adults with T2DM. Random-effects model meta-analysis was performed to obtain pooled mean difference (MD) of change from baseline for continuous outcomes and risk ratio (RR) for dichotomous outcomes. Primary outcomes considered were HbA1c and key gastrointestinal (GI) symptoms (abdominal discomfort or pain, diarrhea, dyspepsia, and nausea & vomiting).

RESULTS

Nine RCTs that randomized a total of 2609 adults revealed that MIR was statistically associated with better HbA1c lowering (MD 0.09% [95% confidence interval or CI, 0.01%, 0.17%]), MXR only reduced dyspepsia (RR 0.58 [95% CI, 0.34, 0.98]), and both formulations were associated with similar cumulative incidence of other key GI symptoms.

CONCLUSIONS

MXR was associated with statistically worse but likely clinically similar HbA1c lowering and minimal improvement of GI intolerance compared to MIR. Protocol Registration: PROSPERO (CRD42019148008).

Metformin Affects Cardiac Arachidonic Acid Metabolism and Cardiac Lipid Metabolite Storage in a Prediabetic Rat Model

Metformin can reduce cardiovascular risk independent of glycemic control. The mechanisms behind its non-glycemic benefits, which include decreased energy intake, lower blood pressure and improved lipid and fatty acid metabolism, are not fully understood. In our study, metformin treatment reduced myocardial accumulation of neutral lipids—triglycerides, cholesteryl esters and the lipotoxic intermediates—diacylglycerols and lysophosphatidylcholines in a prediabetic rat model (p < 0.001). We observed an association between decreased gene expression and SCD-1 activity (p < 0.05). In addition, metformin markedly improved phospholipid fatty acid composition in the myocardium, represented by decreased SFA profiles and increased n3-PUFA profiles. Known for its cardioprotective and anti-inflammatory properties, metformin also had positive effects on arachidonic acid metabolism and CYP-derived arachidonic acid metabolites. We also found an association between increased gene expression of the cardiac isoform CYP2c with increased 14,15-EET (p < 0.05) and markedly reduced 20-HETE (p < 0.001) in the myocardium. Based on these results, we conclude that metformin treatment reduces the lipogenic enzyme SCD-1 and the accumulation of the lipotoxic intermediates diacylglycerols and lysophosphatidylcholine. Increased CYP2c gene expression and beneficial effects on CYP-derived arachidonic acid metabolites in the myocardium can also be involved in cardioprotective effect of metformin.

Knowledge, Attitude, and Practice of Metformin Extended-Release Tablets Among Clinicians in China: A Cross-Sectional Survey

Background: Metformin extended-release (XR) is a once-daily alternative conventional immediate-release (IR) tablet for adults with type 2 diabetes.

Aim: This study aimed to investigate the knowledge, attitude, and practice of the use of metformin XR tablets among clinicians.

Methods: We conducted a cross-sectional online survey among endocrinologists, general practitioners, and internists, who are taking routine care of adults with type 2 diabetes in health institutes at all levels in Sichuan Province, China. We designed an online questionnaire including the demographic information, knowledge, attitude, and practice about metformin XR tablets.

Results: We included 158 clinicians, 67.7% of whom were females and 63.9% were from tertiary hospitals. The median age was 39.6 years (ranging between 22 and 62 years). Only 8.2% of the clinicians correctly answered the knowledge questions, 82.3% and 62.0% of the responders assumed that metformin XR had superior efficacy and tolerability to the metformin IR, respectively. Only 46.8% of the clinicians prescribed the metformin XR based on the patient’s preference for once daily frequency.

Conclusion: The knowledge, attitude, and practice of metformin XR among Chinese clinicians need improving. Clinicians need credible information to support their clinical decision-making regarding metformin XR.

Metformin Reverses Hashimoto's Thyroiditis by Regulating Key Immune Events

Background

Hashimoto's thyroiditis (HT) is a common autoimmune disease characterized by high levels of thyroid peroxidase antibody (TPOAb) and thyroid globulin antibody (TgAb) as well as infiltration of lymphocytes in thyroid. In recent years, metformin has been proven to be effective in a variety of autoimmune diseases, such as systemic lupus erythematosus, rheumatoid arthritis and multiple sclerosis.

Methods

This study systematically explored the therapeutic effect of metformin on HT and its underlying mechanism by comprehensively utilizing methods including animal model, in vitro cell culture and differentiation, mRNA sequencing and 16S rRNA sequencing.

Findings

We found that metformin indeed had a therapeutic effect on mice with HT mainly by reducing TgAb and lymphocyte infiltration in thyroid tissue. In addition, metformin also significantly suppressed the number and function of Th17 cells and M1 macrophages polarization in HT mice. Furthermore, metformin can inhibit the differentiation and function of Th17 in vitro. The results of mRNA sequencing of thyroid tissue illustrated that the therapeutic effect of metformin on HT was mainly achieved by regulating immune pathways. 16S RNA sequencing of the intestinal flora found that the intestinal flora of HT mice differs significantly from that of the normal mice and also were altered by metformin treatment.

Interpretation

These experiments provided a preliminary theoretical basis for the clinical application of metformin in the treatment of HT.

Role of insulin and insulin resistance in androgen excess disorders

Insulin has complex effects on cell growth, metabolism and differentiation, and these effects are mediated by a cell-surface bound receptor and eventually a cascade of intracellular signaling events. Among the several metabolic and growth-promoting effects of insulin, insulin resistance is defined as an attenuated effect of insulin on glucose metabolism, primarily the limited export of blood glucose into skeletal muscle and adipose tissue. On the other hand, not all the signaling pathways and insulin-responsive tissues are equally affected, and some effects other than the metabolic actions of insulin are overexpressed. Ovaries and the adrenal glands are two examples of tissues remaining sensitive to insulin actions where insulin may contribute to increased androgen secretion. Polycystic ovary syndrome (PCOS) is the most common form of androgen excess disorder (AED), and its pathogenesis is closely associated with insulin resistance. Patients with idiopathic hirsutism also exhibit insulin resistance, albeit lower than patients with PCOS. Although it is not as evident as in PCOS, patients with congenital adrenal hyperplasia may have insulin resistance, which may be further exacerbated with glucocorticoid overtreatment and obesity. Among patients with severe insulin resistance syndromes, irrespective of the type of disease, hyperinsulinemia promotes ovarian androgen synthesis independently of gonadotropins. It is highly debated in whom and how insulin resistance should be diagnosed and treated among patients with AEDs, including PCOS. It is not suitable to administer an insulin sensitizer relying on only some mathematical models used for estimating insulin resistance. Instead, the treatment decision should be based on the constellation of the signs, symptoms and presence of obesity; acanthosis nigricans; and some laboratory abnormalities such as impaired glucose tolerance and impaired fasting glucose.

Metformin turns 62 in pharmacotherapy: Emergence of non-glycaemic effects and potential novel therapeutic applications

Metformin is the most commonly prescribed oral antidiabetic medication. Direct/indirect activation of Adenosine Monophosphate-activated protein kinase (AMPK) and non-AMPK pathways, amongst others, are deemed to explain the molecular mechanisms of action of metformin. Metformin is an established insulin receptor sensitising antihyperglycemic agent, is highly affordable, and has superior safety and efficacy profiles. Emerging experimental and clinical evidence suggests that metformin has pleiotropic non-glycemic effects. Metformin appears to have weight stabilising, renoprotective, neuroprotective, cardio-vascular protective, and antineoplastic effects and mitigates polycystic ovarian syndrome. Anti-inflammatory and antioxidant effects of metformin seem to qualify it as an adjunct therapy in treating infectious diseases such as tuberculosis, viral hepatitis, and the current novel Covid-19 infections. So far, metformin is the only prescription medicine relevant to the emerging field of senotherapeutics. Non-glycemic effects of metformin favourable to its repurposing in therapeutic use are hereby discussed.

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

Background

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

Methods

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

Results

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

Conclusion

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

The Protective Effect of Metformin on Abdominal Aortic Aneurysm: A Systematic Review and Meta-Analysis

BACKGROUND

Type 2 diabetes mellitus (T2DM) patients have a lower risk of abdominal aortic aneurysm (AAA) and its comorbidities, which might be associated with the usage of metformin. The objective of the study was to evaluate the role of metformin in the process of AAA development.

METHOD

PubMed, Embase and Cochrane Library were searched up to May 15^th, 2021. We implemented several methods including the risk of bias graph, GRADE system and funnel plot to assess the quality and possible bias of this study. Subgroup analysis and sensitivity analysis were applied to address quality differences and validate the robustness of the final results.

RESULT

Ten articles were enrolled after screening 151 articles searched from databases. The pooled results showed that, compared with T2DM patients without metformin, metformin prescription was associated with a slower annual growth rate of the aneurysm (mean difference (MD) -0.67 cm [95% confidence interval (CI) -1.20 ~ -0.15 cm]). Besides, metformin exposure was associated with a lower frequency of AAA events (odds ratio (OR) 0.61 [95% CI 0.41-0.92]).

CONCLUSION

Metformin alleviated both annual expansion rate and aneurysm rupture frequency in AAA patients with T2DM.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO, identifier https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=217859 (CRD42020217859).

The impact of growth differentiation factor 15 on the risk of cardiovascular diseases: two-sample Mendelian randomization study

BACKGROUND

Growth differentiation factor 15 (GDF-15), a stress responsive cytokine, belongs to transforming growth factor β cytokine superfamily. Some evidence support that it's involved in inflammation, coagulation, oxidative stress, endothelial dysfunction, and hemostasis. However, it's still controversial whether GDF-15 directly contributes to the morbidity and mortality of patients suffered with cardiovascular disease (CVD). Besides prospective cohort study and randomized controlled trial, Mendelian randomization (MR) is a genetic epidemiological method that exploits genetic variants as unbiased proxies for modifiable to determine the causal relationships between exposures and health outcomes. Herein, we introduced a two-sample MR approach to evaluate the causal relationships of circulating GDF-15 levels with major CVDs incidence.

METHODS

Genetic instruments and summary statistics for two-sample MR analysis were obtained from 5 independent large genome-wide association studies (GWAS) to investigate the causal correlation between circulating GDF-15 levels and 9 CVDs, respectively. Conventional inverse variance weighted method was adopted to evaluate the causality of GDF-15 with different outcomes; weighted median and MR egger were used for sensitivity analyses.

RESULTS

Among 9 SNPs identified from 5 GWASs in 2.6 million individuals, 5 SNPs (rs1227731, rs3195944, rs17725099, rs888663, rs749451) coming from chromosome 19 and containing the PGPEP1 and GDF-15 genes were employed. Based on the instruments, circulating GDF-15 levels significantly linked to the increased risk of cardioembolic stroke, atrial fibrillation, coronary artery disease and myocardial infarction. However, no significant causal association was observed for circulating GDF-15 levels with the incidence of any ischemic stroke, large-artery atherosclerotic stroke, small vessel stroke, heart failure and nonischemic cardiomyopathy.

CONCLUSIONS

The MR study provides with genetic evidence for the causal relationship of circulating GDF-15 levels with the increased risk of cardioembolic stroke, atrial fibrillation, coronary artery disease and myocardial infarction, but not any ischemic stroke, large-artery atherosclerotic stroke, small vessel stroke, heart failure and nonischemic cardiomyopathy. It indicates that GDF-15 might be a promising biomarker or potential therapeutic target for some CVDs.

Different Effects of Metformin and A769662 on Sodium Iodate-Induced Cytotoxicity in Retinal Pigment Epithelial Cells: Distinct Actions on Mitochondrial Fission and Respiration

Oxidative stress-associated retinal pigment epithelium (RPE) cell death is critically implicated in the pathogenesis of visual dysfunction and blindness of retinal degenerative diseases. Sodium iodate (NaIO₃) is an oxidative retinotoxin and causes RPE damage. Previously, we found that NaIO₃ can induce human ARPE-19 cell death via inducing mitochondrial fission and mitochondrial dysfunction. Although metformin has been demonstrated to benefit several diseases possibly via AMP-activated protein kinase (AMPK) activation, it remains unknown how AMPK affects retinopathy in NaIO₃ model. Therefore, in this study, we compared the effects of metformin and AMPK activator A769662 on NaIO₃-induced cellular stress and toxicity. We found that A769662 can protect cells against NaIO₃-induced cytotoxicity, while metformin exerts an enhancement in cell death. The mitochondrial reactive oxygen species (ROS) production as well as mitochondrial membrane potential loss induced by NaIO₃ were not altered by both agents. In addition, NaIO₃-induced cytosolic ROS production, possibly from nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activation and counteracting cell death, was not altered by A769662 and metformin. Notably, NaIO₃-induced mitochondrial fission and inhibition of mitochondrial respiration for ATP turnover were reversed by A769662 but not by metformin. In agreement with the changes on mitochondrial morphology, the ERK-Akt signal axis dependent Drp-1 phosphorylation at S616 (an index of mitochondrial fission) under NaIO₃ treatment was blocked by A769662, but not by metformin. In summary, NaIO₃-induced cell death in ARPE cells primarily comes from mitochondrial dysfunction due to dramatic fission and inhibition of mitochondrial respiration. AMPK activation can exert a protection by restoring mitochondrial respiration and inhibition of ERK/Akt/Drp-1 phosphorylation, leading to a reduction in mitochondrial fission. However, inhibition of respiratory complex I by metformin might deteriorate mitochondrial dysfunction and cell death under NaIO₃ stress.

Time course and dose effect of metformin on weight in patients with different disease states

OBJECTIVES

The present study was to quantitate and compare the efficacy of metformin on weight in different disease states using model-based meta-analysis (MBMA).

METHODS

Randomized controlled trials (RCT) of metformin effects on weight in different disease states were collected by searching the public databases. The change rate of weight from baseline was selected as the efficacy indicator.

RESULTS

A total 21 RCTs containing 1885 patients including patients with type 2 diabetes mellitus, patients with antipsychotic induced weight gain, patients with obesity, were included into the present study. After deducting placebo effect, the maximal effect (E_max) of metformin on weight in patients with type 2 diabetes mellitus, patients with antipsychotic induced weight gain, patients with obesity were -6.86%, -8.82%, and -4.14%, respectively. The treatment duration to reach half of the maximal effect (ET₅₀) were 107, 45.5, and 15.1 weeks, respectively. Within the metformin dose range from 21 RCTs, no significant dose-response relationship was observed. However, the time-course relationship is obvious for efficacy of metformin on weight.

CONCLUSIONS

The present study firstly provided quantitative information for metformin effects on weight in different disease states, including patients with type 2 diabetes mellitus, patients with antipsychotic induced weight gain, patients with obesity.

Action of metformin therapy against advanced glycation, oxidative stress and inflammation in type 2 diabetes patients: 3 months follow-up study

BACKGROUND

Persistence hyperglycemia results in the formation of advanced glycation end products (AGEs) by non-enzymatic glycation. AGEs and their receptor RAGE play an important role in generation of inflammatory molecules and oxidative stress. Metformin regulates insulin responsive gene and helps to achieve glycemic control however, no extensive study reported about its role against glycation induced oxidative stress and vascular inflammation. Therefore, present work focused on clinical relevance of three months metformin therapy in type 2 diabetes mellitus patients against glycation induced oxidative stress and vascular inflammation.

METHODS

Among recruited 40 medicated-naive type 2 diabetes mellitus patients, 31 patients were continued with metformin therapy. Biomarkers of plasma protein glycation (fructosamine, protein carbonyls, β-amyloid) antioxidants and oxidative stress markers (GSH, catalase, NO, PON-1, AOPP, LPO; RAGE isoforms (sRAGE, esRAGE); inflammatory markers (IL-6, TNF-α) were determined at baseline and after 3-months of treatment. The expression profile of membrane RAGE, NF-κB, CML was studied in PBMNCs and GLUT-1 in erythrocyte ghost by western blotting.

RESULTS

Metformin showed maximum percent declined from baseline to three months therapy in levels of fructosamine, β-amyloid, sRAGE, inflammatory cytokines (IL-6, TNF-α) and percent increment in esRAGE and antioxidants levels. It showed reduced levels of IL-6 and TNF-α by declining expression of CML, membrane RAGE and NF-κB in type 2 diabetes mellitus patients after three months therapy.

CONCLUSIONS

First report in Indian diabetes mellitus patients, where metformin showed effective inhibition against glycation and receptor mediated cellular inflammation. However, these findings need to be tested in a randomized trial.

The effect of metformin on carotid intima-media thickness (CIMT): A systematic review and meta-analysis of randomized clinical trials

Metformin administration has been reported to influence the carotid intima-media thickness (CIMT) in humans. However, since previously conducted studies have yielded inconsistent results, the exact effect of metformin on CIMT remains unclear. Causes that could lead to inconsistency in reported research could be the duration and dose of the intervention, as well as the sample size. To address this inconsistency, we conducted a systematic review and meta-analysis to evaluate the influence of metformin on CIMT in human subjects. We identified eligible studies by searching several electronic databases (EMBASE, PubMed-MEDLINE, Web of Science and Google Scholar) up to December 12, 2019. Data were pooled using the random-effects model. Combining data from 1087 participants (9 studies), our meta-analysis revealed that the administration of metformin resulted in a significant reduction in CIMT (WMD = -0.049 mm; 95% CI: -0.095, -0.004). Stratified analyses showed that an intervention lasting ≥12 months (WMD: -0.084 mm, 95% CI: -0.145, -0.024) and an intake of metformin ≤1500 mg/day (WMD: -0.081 mm, 95% CI: -0.132, -0.029) resulted in a significantly greater reduction in CIMT. However, an intervention duration of less than 12 months and an intake of metformin ˃1500 mg/day yielded no significant effects on CIMT. The results of the current study confirm that metformin administration is associated with a significant reduction in CIMT. Taking into account that CIMT reflects the burden of atherosclerosis, the clinical utility of metformin might also be related to its anti-atherogenic effects.

Metformin inhibits the activation of melanocortin receptors 2 and 3 in vitro: A possible mechanism for its anti-androgenic and weight balancing effects in vivo?

Metformin is recommended as one of the first-line drugs for the treatment of type 2 diabetes and the metabolic syndrome. In addition to its insulin sensitizing effects, it has been shown to attenuate androgen excess in women with polycystic ovary syndrome (PCOS) or congenital adrenal hyperplasia (CAH), as well as to ameliorate obesity. The mechanisms of metformin action seem manifold. Preclinical studies suggest that it inhibits the cellular stress response at the level of the mitochondrial OXPHOS system and through AMPK dependent and independent mechanisms. Recent studies have shown that metformin decreases ACTH secretion from pituitary and reduces ACTH-stimulated adrenal secretion. In this study we investigated its specific effect through the melanocortin receptor 2 (MC2R) on signaling targeting adrenal steroidogenesis. To assess this effect, we used mouse adrenal OS3 cells, which do not express the MC2R. Cells were transfected with the MC2R and stimulated by ACTH. Downstream cyclic AMP production was then assessed by a co-transfected cAMP-responsive vector producing luciferase that was measured by a dual luciferase assay. The amount of luciferase produced in this assay corresponds to the amount of receptor activation with varying amount of ACTH. The effect of metformin was then tested in this system. We found a significant inhibition of ACTH induced MC2R activation and signaling with 10 mM metformin. The ACTH concentration response curve (CRC) was half-log shifted and a ∼30 % reduction in maximum receptor response (Rmax) to ACTH in presence of metformin was observed. This effect was dose dependent with an IC₅₀ of 4.2 mM. qRT-PCR analyses showed that metformin decreased ACTH induced MC2R expression. Metformin did not affect cell viability and basal cAMP levels. We also tested the effect of metformin on homologous melanocortin receptors (MCRs). No significant effect was found on MC1R and MC4R activity. However, a log shift of EC₅₀ of ACTH stimulation on MC3R was observed with metformin treatment. Metformin also inhibited melanocortin stimulating hormone (αMSH) induced MC3R activity. In conclusion, we show that metformin acts on MC2R and MC3R signaling directly. The role of MC2R for steroidogenesis is well established. MC3R is involved in energy balance and seems to act as a rheostat when the metabolism is challenged. Our study may explain how metformin helps in weight loss and attenuates the excess response to ACTH in androgen excess disorders such as PCOS and CAH.

Metformin Alleviates Left Ventricular Diastolic Dysfunction in a Rat Myocardial Ischemia Reperfusion Injury Model

An increased incidence of myocardial infarction (MI) has recently emerged as the cause of cardiovascular morbidity and mortality worldwide. In this study, cardiac function was investigated in a rat myocardial ischemia/reperfusion (I/R) model using echocardiography. Metformin administration significantly increased ejection fraction and fractional shortening values on Days 3 and 7 when MI occurred, indicating that metformin improved left ventricular systolic function. In the Sham + MET and MI + MET groups, the E' value was significantly different up to Day 3 but not at Day 7. This may mean that left ventricular diastolic function was effectively restored to some extent by Day 7 when metformin was administered. These results suggest that diastolic dysfunction, assessed by echocardiography, does not recover in the early phase of ischemic reperfusion injury in the rat myocardial I/R model. However, administering metformin resulted in recovery in the early phase of ischemic reperfusion injury in this model. Further gene expression profiling of left ventricle tissues revealed that the metformin-treated group had notably attenuated immune and inflammatory profiles. To sum up, a rat myocardial I/R injury model and ultrasound-based assessment of left ventricular systolic and diastolic function can be used in translational research and for the development of new heart failure-related drugs, in addition to evaluating the potential of metformin to improve left ventricular (LV) diastolic function.

Cardiovascular risk following metformin treatment in patients with type 2 diabetes mellitus: Results from meta-analysis

AIM

Pharmacologic therapy for T2DM has proven benefits in terms of reducing elevated blood glucose levels and reducing microvascular complications. However, the impact of metformin on adverse cardiovascular outcomes and cardiovascular mortality is less clear. We carried out this meta-analysis on all published studies to estimate the overall cardiovascular risk following metformin treatment in patients with T2DM.

METHODS

We searched the PubMed, Embase and CNKI (China National Knowledge Infrastructure) databases for all articles. The odds ratio (OR) corresponding to the 95% confidence interval (95% CI) was used to assess the cardiovascular risk following metformin treatment in patients with T2DM. The statistical heterogeneity among studies was assessed with the Q-test and I² statistics.

RESULTS

We collected 16 studies including 25 comparisons with 1,160,254 patients of type 2 diabetes mellitus and 701,843 patients of T2DM following metformin treatment. Our results found statistical evidence of significantly decreased cardiovascular risk to be associated with following treatment with metformin in patients with type 2 diabetes mellitus (OR = 0.57, 95% CI = 0.48-0.68) (shown in Table 1 and Fig. 2), both with the mortality (OR = 0.44, 95% CI = 0.34-0.57) and incidence (OR = 0.73, 95% CI = 0.59-0.90).

CONCLUSIONS

Our meta-analysis indicated that following metformin treatment in patients with T2DM was associated with decreased cardiovascular risk, both with the mortality and incidence. However, the heterogeneity among studies may potentially affect the final results.

Metformin as Potential Therapy for High-Grade Glioma

Metformin (MET), 1,1-dimethylbiguanide hydrochloride, is a biguanide drug used as the first-line medication in the treatment of type 2 diabetes. The recent years have brought many observations showing metformin in its new role. The drug, commonly used in the therapy of diabetes, may also find application in the therapy of a vast variety of tumors. Its effectiveness has been demonstrated in colon, breast, prostate, pancreatic cancer, leukemia, melanoma, lung and endometrial carcinoma, as well as in gliomas. This is especially important in light of the poor options offered to patients in the case of high-grade gliomas, which include glioblastoma (GBM). A thorough understanding of the mechanism of action of metformin can make it possible to discover new drugs that could be used in neoplasm therapy.

Risks of Dysglycemia Over the First 4 Years After a Hypertensive Disorder of Pregnancy

BACKGROUND

Women with the hypertensive disorders of pregnancy (HDP) (preeclampsia [PE] and gestational hypertension [GHTN]) have increased risks of future diabetes. Postpartum glycemic testing offers early identification and treatment of dysglycemia, but evidence-based recommendations for this high-risk population are lacking. The objective of this study was to describe the risks of developing dysglycemia in women with normotensive and hypertensive pregnancies over the first 4 years postpartum.

METHODS

The Discharge Abstract Database was used to identify women who delivered singleton live-born infants in Calgary, Alberta, Canada, between January 2010 and December 2012 (N=27,300). This was linked with Calgary Laboratory Services (for glycemic tests) and the Pharmaceutical Information Network databases (for antidiabetes medication prescriptions) over the first 4 years postpartum. Logistic regression analyses compared glycemic testing and results were adjusted for maternal age, gestational age, parity and the Pampalon deprivation index.

RESULTS

Women with HDP had more glycemic testing (GHTN 67.8% and PE 69.9% vs normotensive 60.9%; p<0.001) and significantly higher results for fasting plasma glucose (GHTN 4.82±0.51 mmol/L and PE 4.84±0.54 mmol/L vs normotensive 4.73±0.49 mmol/L; p<0.001), random plasma glucose (GHTN 5.20±0.96 mmol/L and PE 5.39±1.71 mmol/L vs normotensive 5.00±0.87 mmol/L; p<0.001) and glycated hemoglobin levels (PE 5.62±0.53% vs normotensive 5.49±0.32%; p<0.001). Women with HDP had a higher adjusted odds (95% confidence interval) of developing type 2 diabetes compared with normotensive women (GHTN: 2.26, 1.50 to 13.4; PE: 2.02, 0.91 to 4.46).

CONCLUSIONS

The high prevalence of early dysglycemia highlights the importance of targeted postpartum glycemic testing in women after HDP. Further research on optimal glycemic testing (specific tests and timing) in these high-risk women is needed.

Understanding the glucoregulatory mechanisms of metformin in type 2 diabetes mellitus

Despite its position as the first-line drug for treatment of type 2 diabetes mellitus, the mechanisms underlying the plasma glucose level-lowering effects of metformin (1,1-dimethylbiguanide) still remain incompletely understood. Metformin is thought to exert its primary antidiabetic action through the suppression of hepatic glucose production. In addition, the discovery that metformin inhibits the mitochondrial respiratory chain complex 1 has placed energy metabolism and activation of AMP-activated protein kinase (AMPK) at the centre of its proposed mechanism of action. However, the role of AMPK has been challenged and might only account for indirect changes in hepatic insulin sensitivity. Various mechanisms involving alterations in cellular energy charge, AMP-mediated inhibition of adenylate cyclase or fructose-1,6-bisphosphatase 1 and modulation of the cellular redox state through direct inhibition of mitochondrial glycerol-3-phosphate dehydrogenase have been proposed for the acute inhibition of gluconeogenesis by metformin. Emerging evidence suggests that metformin could improve obesity-induced meta-inflammation via direct and indirect effects on tissue-resident immune cells in metabolic organs (that is, adipose tissue, the gastrointestinal tract and the liver). Furthermore, the gastrointestinal tract also has a major role in metformin action through modulation of glucose-lowering hormone glucagon-like peptide 1 and the intestinal bile acid pool and alterations in gut microbiota composition.

Metformin represses the pathophysiology of AAA by suppressing the activation of PI3K/AKT/mTOR/autophagy pathway in ApoE-/- mice

Background

The protective effect of metformin (MET) on abdominal aortic aneurysm (AAA) has been reported. However, the related mechanism is still poor understood. In this study, we deeply investigated the role of metformin in AAA pathophysiology.

Methods

Angiotensin II (Ang-II) was used to construct the AAA model in ApoE^−/− mice. The related mechanism was explored using Western blot and quantitative real time PCR (qRT-PCR). We also observed the morphological changes in the abdominal aorta and the influence of metformin on biological behaviors of rat abdominal aortic VSMCs.

Results

The PI3K/AKT/mTOR pathway was activated in aneurysmal wall tissues of AAA patients and rat model. Treatment with metformin inhibited the breakage and preserved the elastin structure of the aorta, the loss of collagen, and the apoptosis of aortic cells. In addition, metformin significantly suppressed the activation of the PI3K/AKT/mToR pathway and decreased the mRNA and protein levels of LC3B and Beclin1, which were induced by Ang-II. Moreover, PI3K inhibitors enhanced the effect of metformin while PI3K agonists largely reversed this effect. Interestingly, the cell proliferation, apoptosis, migration and autophagy of vascular smooth muscle cells (VSMCs) induced by Ang-II were also decreased following metformin treatment. PI3K inhibitors and agonists strengthened and weakened the effects of metformin in VSMCs, respectively.

Conclusions

Metformin represses the pathophysiology of AAA by inhibiting the activation of PI3K/AKT/mTOR/autophagy pathway. This repression may be useful as a new therapeutic strategy for AAA.

Practical Insights Into Improving Adherence to Metformin Therapy in Patients With Type 2 Diabetes

IN BRIEF Adherence to metformin-based treatment regimens for type 2 diabetes is currently suboptimal due to a complex array of patient-, treatment-, and physician-related barriers, including physical and psychological swallowing difficulties associated with large tablets and gastrointestinal disturbances. Patients often avoid discussing these issues with their primary care providers, and delays in addressing them can lead to reduced glycemic control. This article reviews the issues commonly responsible for poor adherence to metformin and presents strategies to improve compliance, including shared decision-making and the use of different metformin formulations, including liquid metformin.

The Impact of Ethinyl Estradiol on Metformin Action on Prolactin Levels in Women with Hyperprolactinemia

Background Metformin reduced prolactin levels only in women with hyperprolactinemia.

Objective The purpose of this case-control study was to compare metformin action on lactoctrope function between women receiving oral contraceptive pills and women not using hormonal contraception.

Methods The study included two groups of matched women with elevated prolactin levels and new-onset prediabetes or diabetes. The first group consisted of 20 women using oral contraceptive pills for at least 12 months before entering the study, while the second group included 20 patients not using any hormonal contraception. Over the whole study period, all women were treated with metformin (1.7–3 g daily). Circulating levels of glucose, insulin, prolactin, thyrotropin, free thyroid hormones, adrenocorticotropic hormone, gonadotropins and insulin-like growth factor-1 were measured at the beginning and at the end of the study (16 weeks later).

Results Thirty-eight patients completed the study. Metformin reduced plasma glucose levels and improved insulin sensitivity but the latter effect was stronger in women receiving oral contraceptive pills than in women not using any contraception. Although metformin treatment decreased plasma prolactin levels in both study groups, this effect was stronger in women taking oral contraceptive pills. Only in this group of women, metformin increased plasma luteinizing hormone levels. The changes in plasma prolactin correlated with their baseline insulin sensitivity and the effect of metformin on insulin sensitivity. Metformin did not affect plasma levels of thyrotropin, free thyroxine, free triiodothyronine, follicle-stimulating hormone, adrenocorticotropic hormone and insulin-like growth factor-1.

Conclusions The obtained results suggest that the effect of metformin on overactive lactotropes depends on estrogen levels.