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

Causal association of metformin treatment with diverse immune-mediated inflammatory diseases: A Mendelian randomization analysis

Metformin has been shown to possess immune-modulating and anti-inflammatory effects in various animal and clinical studies. It is believed to be effective in treating some immune-mediated inflammatory diseases (IMIDs). However, there remains ongoing debate regarding the extent to which metformin can reduce the risk of developing IMIDs. We used the data from genome-wide association studies to explore the causal relationship between metformin treatment and some IMIDs through the Mendelian randomization (MR) analysis. Additionally, sensitivity analyses were performed using the Cochran Q-test, MR-PRESSO and "leave-one-out" to confirm the robustness of our conclusions. The MR analysis indicated that metformin treatment could reduce the risk of rheumatoid arthritis (RA) (OR = 0.018, 95% CI: 1.33 × 10-3-0.233, P = .002), multiple sclerosis (MS) (OR = 0.966, 95% CI: 0.936-0.997, P = .030) and primary sclerosing cholangitis (PSC) (OR = 6.82 × 10-4, 95% CI: 7.83 × 10-6-5.93 × 10-2, P = .001). But metformin treatment is not significantly associated with the risk of Crohn disease (OR = 0.994, 95% CI: 0.979-1.009, P = .431), ulcerative colitis (UC) (OR = 0.987, 95% CI: 0.965-1.009, P = .234), systemic lupus erythematosus (SLE) (OR = 164.373, 95% CI: 0.158-1.71 × 105, P = .150), autoimmune hepatitis (AIH) (OR = 2.909, 95% CI: 4.58 × 10-3-1.85 × 103, P = .746) and primary biliary cholangitis (PBC) (OR = 0.055, 95% CI: 1.44 × 10-3-2.112, P = .119). Due to the heterogeneity of the data from UC, SLE, MS, and PBC, we adjusted them. After adjustment, there is no change in the results for UC, SLE, MS, and PBC. The findings of this study support metformin treatment may reduce the risk of RA, MS, and PSC.

Bibliometric analysis of metformin as an immunomodulator (2013-2024)

Background

Metformin, the frontline treatment for diabetes, has considerable potential as an immunomodulator; however, detailed bibliometric analyses on this subject are limited.

Methods

This study extracted 640 relevant articles from the Web of Science (WOS) Core Collection and conducted visual analyses using Microsoft Excel, VOSviewer, and CiteSpace.

Results

The findings showed that research on the immunomodulatory function of metformin has grown steadily since 2017, with China and the United States being the leading contributors. These studies have mostly been published in journals such as the International Journal of Molecular Sciences, Cancers, Frontiers in Immunology, and Scientific Reports. Keyword co-occurrence analysis highlighted metformin's role as an immunomodulator, particularly in the context of the tumor immune microenvironment, immunosuppressive checkpoints, and metformin derivatives. Recent research has highlighted metformin's application in aging, autoimmune diseases, COVID-19, and tuberculosis. Additionally, its role in regulating inflammation and gut microbiota is also being investigated.

Conclusion

Overall, the immunomodulatory effects of metformin were investigated in anti-tumor, antiviral, anti-aging, and autoimmune disease research. This highlights the scope of metformin use in these fields, while also significantly enhancing its clinical value as a repurposed drug.

The Gut Microbiota-Related Antihyperglycemic Effect of Metformin

It is critical to sustain the diversity of the microbiota to maintain host homeostasis and health. Growing evidence indicates that changes in gut microbial biodiversity may be associated with the development of several pathologies, including type 2 diabetes mellitus (T2DM). Metformin is still the first-line drug for treatment of T2DM unless there are contra-indications. The drug primarily inhibits hepatic gluconeogenesis and increases the sensitivity of target cells (hepatocytes, adipocytes and myocytes) to insulin; however, increasing evidence suggests that it may also influence the gut. As T2DM patients exhibit gut dysbiosis, the intestinal microbiome has gained interest as a key target for metabolic diseases. Interestingly, changes in the gut microbiome were also observed in T2DM patients treated with metformin compared to those who were not. Therefore, the aim of this review is to present the current state of knowledge regarding the association of the gut microbiome with the antihyperglycemic effect of metformin. Numerous studies indicate that the reduction in glucose concentration observed in T2DM patients treated with metformin is due in part to changes in the biodiversity of the gut microbiota. These changes contribute to improved intestinal barrier integrity, increased production of short-chain fatty acids (SCFAs), regulation of bile acid metabolism, and enhanced glucose absorption. Therefore, in addition to the well-recognized reduction of gluconeogenesis, metformin also appears to exert its glucose-lowering effect by influencing gut microbiome biodiversity. However, we are only beginning to understand how metformin acts on specific microorganisms in the intestine, and further research is needed to understand its role in regulating glucose metabolism, including the impact of this remarkable drug on specific microorganisms in the gut.

The Effects of Metformin on Weight Loss, Cardiovascular Health, and Longevity

Metformin, a biguanide derived from Galega officinalis, was first synthesized by Werner and Bell in 1922. Metformin was approved for the treatment of diabetes by the US Food and Drug Administration in 1994. It has since become the most widely used oral antidiabetic agent. The exact mechanisms by which metformin exerts its clinical effects remain the subject of ongoing research. Metformin interacts with multiple molecular pathways, and the downstream effects of which affect weight, cardiovascular health, and longevity. Metformin reduces hunger by mitigating insulin resistance in the hypothalamic pro-opiomelanocortin neurons. It enhances satiety by stimulating the enteral release of glucagon-like peptide 1. It also induces favorable changes to enteric microbiota, enhancing metabolism. These effects cumulatively contribute to metformin-induced weight loss. Metformin use has shown associations with improved cardiovascular outcomes including reduced all-cause mortality, lower rates of myocardial infarctions, and improved heart failure outcomes. Many of these actions are mediated through the direct activation of adenosine monophosphate-activated kinase (AMPK), which, in turn, enhances cellular energy production and endothelial nitric oxide synthase-mediated vascular relaxation. It antagonizes proinflammatory cytokines, reducing cardiac fibrosis and remodeling. The metformin-AMPK pathway may also explain the potential utility of metformin in mitigating aging. Acting through AMPK, it inhibits the mammalian target of rapamycin, leading to increased autophagy and cell growth. The metformin-AMPK-sirtuin pathway may also contribute to longevity. In this review, we will discuss the use of metformin in weight loss, cardiovascular health, and longevity, highlighting the historic background, molecular mechanisms, and current evidence.

Guanidine dicycloamine-based analogs: green chemistry synthesis, biological investigation, and molecular docking studies as promising antibacterial and antiglycation leads

Dicyandiamide (DCD) reacted with amino acids 1a-f to produce biguanides 2 and 4 and guanidine pyrazolones 3, 5, 6, 7, and 8, according to the reaction. DCD exhibited the following reactions: imidodicarbonimidicdiamide 9, diazocan-2-ylguanidine 10, methyl biguanidylthion 11, N-carbamothioylimidodicarbonimidicdiamide 12, 2-guanidinebenzoimidazole 13a, 2-guanidinylbenzoxazole 13b, and 2-guanidinylbenzothiazol 13c. These reactions were triggered by 6-amino caproic acid, thioacetamide, thiourea, o-aminophenol, o-aminothiophenol, and anthranilic acid, respectively. Compound 2 had the least antimicrobial activity, while compound 13c demonstrated the most antibacterial impact against all bacterial strains. Furthermore, in terms of antiglycation efficacy (AGEs), 12, 11, and 7 were the most effective AGE cross-linking inhibitors. Eight and ten, which showed a considerable inhibition on cross-linking AGEs, come next. Compounds 4 and 6 on the other hand have shown the least suppression of AGE production. The most promising antiglycation scaffolds 8, 11, and 12 in the Human serum albumin (HAS) active site were shown to be able to adopt crucial binding interactions with important amino acids based on the results of in silico molecular docking. The most promising antiglycation compounds 8, 11, and 12 were also shown to have better hydrophilicity, acceptable lipophilicity, gastrointestinal tract absorption (GIT), and blood-brain barrier penetration qualities when their physicochemical properties were examined using the egg-boiled method.

Metformin increases gut multidrug resistance genes in type 2 diabetes, potentially linked to Escherichia coli

Metformin is the most commonly prescribed medication for treating type 2 diabetes (T2D). It is known that metformin can alter the gut microbiome, which influences the effectiveness of metformin treatment. We posited that if the gut microbiome, a reservoir of the resistome, is altered, then the resistome should change as well. To test this hypothesis, we reanalyzed microbiome data generated by Wu et al. (Nat Med 23(7):850-858, 2017), identifying antibiotic resistance genes (ARGs) and bacterial species. Through read-based analysis, we observed that the abundance of ARGs indeed changed in many samples treated with metformin. Moreover, the altered pattern was sufficiently heterogeneous across individual samples to allow subcategorization. We also found a strong correlation between the abundance of multidrug-resistant ARGs (MDR-ARGs) and the presence of E. coli. The contig-based analysis led to the same conclusion: an increase in MDR-ARGs due to metformin was associated with an increase in E. coli. In relation to this, we were able to confirm that the majority of MDR-ARGs are likely to originate from E. coli. These results suggest that metformin may have the potential side effect of increasing E. coli carrying ARGs, particularly MDR-ARGs, which could be a concern in T2D therapy that relies on metformin.

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.

Genetic analysis: Therapeutic drug monitoring of metformin and glimepiride on diabetic patients' plasma including genetic polymorphism

Diabetes is a widespread disease that needs to be controlled. Therapeutic monitoring of drugs is very helpful in maintaining desirable doses. To study a correlation between the blood level of metformin (to a lesser extent, glimepiride) and genotyping (mainly the SULT1A1 genotype). Determine drug levels using a validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) tool. A validated LC-MS/MS method was developed to determine metformin and glimepiride levels in human plasma. DNA extraction was performed using Jena Bioscience's Blood DNA preparation, in which a column kit was used to extract DNA for genetic polymorphism. The investigation was carried out using both medications in type 2 diabetes patients alongside the genetic polymorphism. One hundred and six patients were assessed. The prevalence of homozygosity for SULT1A1 and wild-type CYP2D6 * 4 were 72.6% and 73.6%, respectively. After adjustment for daily intake of metformin, three patients out of five with the highest levels of metformin had no homozygosity (SULT1A1 genotype). Statistically, variables that demonstrated an insignificant correlation with the level of metformin were body mass index (rs (87) = 0.32, P = 0.011) and age (rs (87) =0.26, P = 0.017). The homozygous (SULT1A1 genotype) correlation was moderate (rs (87) =0.21, P = 0.052). According to the findings, patients with the wt/wt CYP2D6 genotype had considerably greater levels of endoxifen than those with the v/v CYP2D6 genotype. The study's results reported a probable correlation between the blood level of metformin (to a lesser extent, glimepiride) and genotyping (mainly the SULT1A1 genotype). Genotype-guided drug therapy may provide a novel contribution to maximize drug efficacy and/or minimize toxicity.

Advances in the mechanism of metformin with wide-ranging effects on regulation of the intestinal microbiota

Metformin is of great focus because of its high safety, low side effects, and various effects other than lowering blood sugar, such as anti-inflammation, anti-tumor, and anti-aging. Studies have shown that metformin has a modulating effect on the composition and function of the intestinal microbiota other than acting on the liver. However, the composition of microbiota is complex and varies to some extent between species and individuals, and the experimental design of each study is also different. Multiple factors present a major obstacle to better comprehending the effects of metformin on the gut microbiota. This paper reviews the regulatory effects of metformin on the gut microbiota, such as increasing the abundance of genus Akkermansia, enriching short-chain fatty acids (SCFAs)-producing bacterial genus, and regulating gene expression of certain genera. The intestinal microbiota is a large and vital ecosystem in the human body and is considered to be the equivalent of an "organ" of the human body, which is highly relevant to human health and disease status. There are a lot of evidences that the gut microbiota is responsible for metformin's widespread effects. However, there are only a few systematic studies on this mechanism, and the specific mechanism is still unclear. This paper aims to summarize the possible mechanism of metformin in relation to gut microbiota.

Advances in Anti-Cancer Drug Development: Metformin as Anti-Angiogenic Supplemental Treatment for Glioblastoma

According to the WHO 2016 classification, glioblastoma is the most prevalent primary tumor in the adult central nervous system (CNS) and is categorized as grade IV. With an average lifespan of about 15 months from diagnosis, glioblastoma has a poor prognosis and presents a significant treatment challenge. Aberrant angiogenesis, which promotes tumor neovascularization and is a prospective target for molecular target treatment, is one of its unique and aggressive characteristics. Recently, the existence of glioma stem cells (GSCs) within the tumor, which are tolerant to chemotherapy and radiation, has been linked to the highly aggressive form of glioblastoma. Anti-angiogenic medications have not significantly improved overall survival (OS), despite various preclinical investigations and clinical trials demonstrating encouraging results. This suggests the need to discover new treatment options. Glioblastoma is one of the numerous cancers for which metformin, an anti-hyperglycemic medication belonging to the Biguanides family, is used as first-line therapy for type 2 diabetes mellitus (T2DM), and it has shown both in vitro and in vivo anti-tumoral activity. Based on these findings, the medication has been repurposed, which has shown the inhibition of many oncopromoter mechanisms and, as a result, identified the molecular pathways involved. Metformin inhibits cancer cell growth by blocking the LKB1/AMPK/mTOR/S6K1 pathway, leading to selective cell death in GSCs and inhibiting the proliferation of CD133+ cells. It has minimal impact on differentiated glioblastoma cells and normal human stem cells. The systematic retrieval of information was performed on PubMed. A total of 106 articles were found in a search on metformin for glioblastoma. Out of these six articles were Meta-analyses, Randomized Controlled Trials, clinical trials, and Systematic Reviews. The rest were Literature review articles. These articles were from the years 2011 to 2024. Appropriate studies were isolated, and important information from each of them was understood and entered into a database from which the information was used in this article. The clinical trials on metformin use in the treatment of glioblastoma were searched on clinicaltrials.gov. In this article, we examine and evaluate metformin's possible anti-tumoral effects on glioblastoma, determining whether or not it may appropriately function as an anti-angiogenic substance and be safely added to the treatment and management of glioblastoma patients.

Anti-Inflammatory Potential of the Anti-Diabetic Drug Metformin in the Prevention of Inflammatory Complications and Infectious Diseases Including COVID-19: A Narrative Review

Metformin, a widely used first-line anti-diabetic therapy for the treatment of type-2 diabetes, has been shown to lower hyperglycemia levels in the blood by enhancing insulin actions. For several decades this drug has been used globally to successfully control hyperglycemia. Lactic acidosis has been shown to be a major adverse effect of metformin in some type-2 diabetic patients, but several studies suggest that it is a typically well-tolerated and safe drug in most patients. Further, recent studies also indicate its potential to reduce the symptoms associated with various inflammatory complications and infectious diseases including coronavirus disease 2019 (COVID-19). These studies suggest that besides diabetes, metformin could be used as an adjuvant drug to control inflammatory and infectious diseases. In this article, we discuss the current understanding of the role of the anti-diabetic drug metformin in the prevention of various inflammatory complications and infectious diseases in both diabetics and non-diabetics.

Metformin: From Diabetes to Cancer-Unveiling Molecular Mechanisms and Therapeutic Strategies

Metformin, a widely used anti-diabetic drug, has garnered attention for its potential in cancer management, particularly in breast and colorectal cancer. It is established that metformin reduces mitochondrial respiration, but its specific molecular targets within mitochondria vary. Proposed mechanisms include inhibiting mitochondrial respiratory chain Complex I and/or Complex IV, and mitochondrial glycerophosphate dehydrogenase, among others. These actions lead to cellular energy deficits, redox state changes, and several molecular changes that reduce hyperglycemia in type 2 diabetic patients. Clinical evidence supports metformin's role in cancer prevention in type 2 diabetes mellitus patients. Moreover, in these patients with breast and colorectal cancer, metformin consumption leads to an improvement in survival outcomes and prognosis. The synergistic effects of metformin with chemotherapy and immunotherapy highlights its potential as an adjunctive therapy for breast and colorectal cancer. However, nuanced findings underscore the need for further research and stratification by molecular subtype, particularly for breast cancer. This comprehensive review integrates metformin-related findings from epidemiological, clinical, and preclinical studies in breast and colorectal cancer. Here, we discuss current research addressed to define metformin's bioavailability and efficacy, exploring novel metformin-based compounds and drug delivery systems, including derivatives targeting mitochondria, combination therapies, and novel nanoformulations, showing enhanced anticancer effects.

Understanding the action mechanisms of metformin in the gastrointestinal tract

Metformin is the initial medication recommended for the treatment of type 2 diabetes mellitus (T2DM). In addition to diabetes treatment, the function of metformin also can be anti-aging, antiviral, and anti-inflammatory. Nevertheless, further exploration is required to fully understand its mode of operation. Historically, the liver has been acknowledged as the main location where metformin reduces glucose levels, however, there is increasing evidence suggesting that the gastrointestinal tract also plays a significant role in its action. In the gastrointestinal tract, metformin effects glucose uptake and absorption, increases glucagon-like peptide-1 (GLP-1) secretion, alters the composition and structure of the gut microbiota, and modulates the immune response. However, the side effects of it cannot be ignored such as gastrointestinal distress in patients. This review outlines the impact of metformin on the digestive system and explores potential explanations for variations in metformin effectiveness and adverse effects like gastrointestinal discomfort.

Contribution of intestinal triglyceride-rich lipoproteins to residual atherosclerotic cardiovascular disease risk in individuals with type 2 diabetes on statin therapy

AIMS/HYPOTHESIS

This study explored the hypothesis that significant abnormalities in the metabolism of intestinally derived lipoproteins are present in individuals with type 2 diabetes on statin therapy. These abnormalities may contribute to residual CVD risk.

METHODS

To investigate the kinetics of ApoB-48- and ApoB-100-containing lipoproteins, we performed a secondary analysis of 11 overweight/obese individuals with type 2 diabetes who were treated with lifestyle counselling and on a stable dose of metformin who were from an earlier clinical study, and compared these with 11 control participants frequency-matched for age, BMI and sex. Participants in both groups were on a similar statin regimen during the study. Stable isotope tracers were used to determine the kinetics of the following in response to a standard fat-rich meal: (1) apolipoprotein (Apo)B-48 in chylomicrons and VLDL; (2) ApoB-100 in VLDL, intermediate-density lipoprotein (IDL) and LDL; and (3) triglyceride (TG) in VLDL.

RESULTS

The fasting lipid profile did not differ significantly between the two groups. Compared with control participants, in individuals with type 2 diabetes, chylomicron TG and ApoB-48 levels exhibited an approximately twofold higher response to the fat-rich meal, and a twofold higher increment was observed in ApoB-48 particles in the VLDL1 and VLDL2 density ranges (all p < 0.05). Again comparing control participants with individuals with type 2 diabetes, in the latter, total ApoB-48 production was 25% higher (556 ± 57 vs 446 ± 57 mg/day; p < 0.001), conversion (fractional transfer rate) of chylomicrons to VLDL was around 40% lower (35 ± 25 vs 82 ± 58 pools/day; p=0.034) and direct clearance of chylomicrons was 5.6-fold higher (5.6 ± 2.2 vs 1.0 ± 1.8 pools/day; p < 0.001). During the postprandial period, ApoB-48 particles accounted for a higher proportion of total VLDL in individuals with type 2 diabetes (44%) compared with control participants (25%), and these ApoB-48 VLDL particles exhibited a fivefold longer residence time in the circulation (p < 0.01). No between-group differences were seen in the kinetics of ApoB-100 and TG in VLDL, or in LDL ApoB-100 production, pool size and clearance rate. As compared with control participants, the IDL ApoB-100 pool in individuals with type 2 diabetes was higher due to increased conversion from VLDL2.

CONCLUSIONS/INTERPRETATION

Abnormalities in the metabolism of intestinally derived ApoB-48-containing lipoproteins in individuals with type 2 diabetes on statins may help to explain the residual risk of CVD and may be suitable targets for interventions.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02948777.

Metformin: update on mechanisms of action and repurposing potential

Currently, metformin is the first-line medication to treat type 2 diabetes mellitus (T2DM) in most guidelines and is used daily by >200 million patients. Surprisingly, the mechanisms underlying its therapeutic action are complex and are still not fully understood. Early evidence highlighted the liver as the major organ involved in the effect of metformin on reducing blood levels of glucose. However, increasing evidence points towards other sites of action that might also have an important role, including the gastrointestinal tract, the gut microbial communities and the tissue-resident immune cells. At the molecular level, it seems that the mechanisms of action vary depending on the dose of metformin used and duration of treatment. Initial studies have shown that metformin targets hepatic mitochondria; however, the identification of a novel target at low concentrations of metformin at the lysosome surface might reveal a new mechanism of action. Based on the efficacy and safety records in T2DM, attention has been given to the repurposing of metformin as part of adjunct therapy for the treatment of cancer, age-related diseases, inflammatory diseases and COVID-19. In this Review, we highlight the latest advances in our understanding of the mechanisms of action of metformin and discuss potential emerging novel therapeutic uses.

Impact of novel glucose-lowering therapies on physical function in people with type 2 diabetes: A systematic review and meta-analysis of randomised placebo-controlled trials

AIMS

We investigated evidence from randomised, placebo-controlled trials of novel glucose-lowering therapies; sodium-glucose co-transporter-2 inhibitors (SGLT2i), dipeptidyl peptidase-4 inhibitors (DPP4i) and glucagon-like peptide-1 receptor agonists (GLP-1RA), on physical function in people with type 2 diabetes (T2D).

METHODS

PubMed, Medline, Embase and Cochrane library were searched from 1 April 2005 to 20 January 2022. The primary outcome was change in physical function in groups receiving a novel glucose-lowering therapy versus placebo at the trial end-point.

RESULTS

Eleven studies met our criteria including nine for GLP-1RA and one each for SGLT2i and DPP4i. Eight studies included a self-reported measure of physical function, seven with GLP-1RA. Pooled meta-analysis showed an improvement of 0.12 (0.07, 017) points in favour of novel glucose-lowering therapies, mainly GLP-1RA. These findings were consistent when assessed individually for commonly used subjective assessments of physical function; namely the Short-Form 36 item-questionnaire (SF-36; all investigating GLP-1RA) and the Impact of Weight on Quality of Life-Lite (IWQOL-LITE; all, except one, exploring GLP-1RA) with estimated treatment differences (ETDs) of 0.86 (0.28, 1.45) and 3.72 (2.30, 5.15) respectively in favour of novel GLTs. For objective measures of physical function (VO_2max and 6-minute walk test (6MWT)) no significant between-group differences between the intervention and the placebo were found.

CONCLUSIONS

GLP-1RAs showed improvements in self-reported outcomes of physical function. However, there is limited evidence to draw definitive conclusions especially because of lack of studies exploring the impact of SGLT2i and DPP4i on physical function. There is a need for dedicated trials to establish the association between novel agents and physical function.

Glucose-Responsive Microparticle-Loaded Dissolving Microneedles for Selective Delivery of Metformin: A Proof-of-Concept Study

Diabetes mellitus (DM) is a metabolic disorder that is one of the most common health problems in the world, primarily type 2 DM (T2DM). Metformin (MTF), as the first-line treatment of DMT2, is effective in lowering glucose levels, but its oral administration causes problems, including gastrointestinal side effects, low bioavailability, and the risk of hypoglycemia. In this study, we formulated MTF into microparticles incorporating a glucose-responsive polymer (MP-MTF-GR), which could potentially increase the bioavailability and extend and control the release of MTF according to glucose levels. This system was delivered by dissolving microneedles (MP-MTF-GR-DMN), applied through the skin, thereby preventing gastrointestinal side effects of orally administered MTF. MP-MTF-GR was formulated using various concentrations of gelatin as a polymer combined with phenylboronic acid (PBA) as a glucose-responsive material. MP-MTF-GR was encapsulated in DMN using polyvinyl pyrrolidone (PVP) and polyvinyl alcohol (PVA) as DMN polymers. The physicochemical evaluation of MP-MTF-GR showed that MTF could be completely entrapped in MP with the percentage of MTF trapped increasing with increasing gelatin concentration without changing the chemical structure of MTF and producing stable MP. In addition, the results of the physicochemical evaluation of MP-MTF-GR-DMN showed that DMN had adequate mechanical strength properties and penetration ability and was stable to environmental changes. The results of the in vitro release and ex vivo permeation study on media with various concentrations of glucose showed that the release and permeation of MTF from the formula increased with increasing glucose levels in the media. The MP-MTF-GR-DMN formula successfully delivered MTF through the skin at 11.30 ± 0.29, 23.31 ± 1.64, 36.12 ± 3.77, and 53.09 ± 3.01 μg from PBS, PBS + glucose 1%, PBS + glucose 2%, and PBS + glucose 4%, respectively, at 24 h, which indicates glucose-responsive permeation and release behavior. The formula developed was also proven to be nontoxic based on hemolysis tests. Importantly, the in vivo study on the rat model showed that this combination approach could provide a better glucose reduction compared to other routes, reducing the blood glucose level to normal levels after 3 h and maintaining this level for 8 h. Furthermore, this approach did not change the skin moisture of the rats. This MP-MTF-GR-DMN is a promising alternative to MTF delivery to overcome MTF problems and increase the effectiveness of T2DM therapy.

Action Mechanism of Metformin and Its Application in Hematological Malignancy Treatments: A Review

Hematologic malignancies (HMs) mainly include acute and chronic leukemia, lymphoma, myeloma and other heterogeneous tumors that seriously threaten human life and health. The common effective treatments are radiotherapy, chemotherapy and hematopoietic stem cell transplantation (HSCT), which have limited options and are prone to tumor recurrence and (or) drug resistance. Metformin is the first-line drug for the treatment of type 2 diabetes (T2DM). Recently, studies identified the potential anti-cancer ability of metformin in both T2DM patients and patients that are non-diabetic. The latest epidemiological and preclinical studies suggested a potential benefit of metformin in the prevention and treatment of patients with HM. The mechanism may involve the activation of the adenosine monophosphate-activated protein kinase (AMPK) signaling pathway by metformin as well as other AMPK-independent pathways to exert anti-cancer properties. In addition, combining current conventional anti-cancer drugs with metformin may improve the efficacy and reduce adverse drug reactions. Therefore, metformin can also be used as an adjuvant therapeutic agent for HM. This paper highlights the anti-hyperglycemic effects and potential anti-cancer effects of metformin, and also compiles the in vitro and clinical trials of metformin as an anti-cancer and chemosensitizing agent for the treatment of HM. The need for future research on the use of metformin in the treatment of HM is indicated.

Type 2 diabetes

Type 2 diabetes accounts for nearly 90% of the approximately 537 million cases of diabetes worldwide. The number affected is increasing rapidly with alarming trends in children and young adults (up to age 40 years). Early detection and proactive management are crucial for prevention and mitigation of microvascular and macrovascular complications and mortality burden. Access to novel therapies improves person-centred outcomes beyond glycaemic control. Precision medicine, including multiomics and pharmacogenomics, hold promise to enhance understanding of disease heterogeneity, leading to targeted therapies. Technology might improve outcomes, but its potential is yet to be realised. Despite advances, substantial barriers to changing the course of the epidemic remain. This Seminar offers a clinically focused review of the recent developments in type 2 diabetes care including controversies and future directions.

Metformin: Is it a drug for all reasons and diseases?

Metformin was first used to treat type 2 diabetes in the late 1950s and in 2022 remains the first-choice drug used daily by approximately 150 million people. An accumulation of positive pre-clinical and clinical data has stimulated interest in re-purposing metformin to treat a variety of diseases including COVID-19. In polycystic ovary syndrome metformin improves insulin sensitivity. In type 1 diabetes metformin may help reduce the insulin dose. Meta-analysis and data from pre-clinical and clinical studies link metformin to a reduction in the incidence of cancer. Clinical trials, including MILES (Metformin In Longevity Study), and TAME (Targeting Aging with Metformin), have been designed to determine if metformin can offset aging and extend lifespan. Pre-clinical and clinical data suggest that metformin, via suppression of pro-inflammatory pathways, protection of mitochondria and vascular function, and direct actions on neuronal stem cells, may protect against neurodegenerative diseases. Metformin has also been studied for its anti-bacterial, -viral, -malaria efficacy. Collectively, these data raise the question: Is metformin a drug for all diseases? It remains unclear as to whether all of these putative beneficial effects are secondary to its actions as an anti-hyperglycemic and insulin-sensitizing drug, or result from other cellular actions, including inhibition of mTOR (mammalian target for rapamycin), or direct anti-viral actions. Clarification is also sought as to whether data from ex vivo studies based on the use of high concentrations of metformin can be translated into clinical benefits, or whether they reflect a 'Paracelsus' effect. The environmental impact of metformin, a drug with no known metabolites, is another emerging issue that has been linked to endocrine disruption in fish, and extensive use in T2D has also raised concerns over effects on human reproduction. The objectives for this review are to: 1) evaluate the putative mechanism(s) of action of metformin; 2) analyze the controversial evidence for metformin's effectiveness in the treatment of diseases other than type 2 diabetes; 3) assess the reproducibility of the data, and finally 4) reach an informed conclusion as to whether metformin is a drug for all diseases and reasons. We conclude that the primary clinical benefits of metformin result from its insulin-sensitizing and antihyperglycaemic effects that secondarily contribute to a reduced risk of a number of diseases and thereby enhancing healthspan. However, benefits like improving vascular endothelial function that are independent of effects on glucose homeostasis add to metformin's therapeutic actions.

Comparative effectiveness of cardiovascular, renal and safety outcomes of second-line antidiabetic drugs use in people with type 2 diabetes: A systematic review and network meta-analysis of randomised controlled trials

AIMS

To compare the cardiovascular, renal and safety outcomes of second-line glucose-lowering agents used in the management of people with type 2 diabetes.

METHODS

MEDLINE, EMBASE and CENTRAL were searched from inception to 13 July 2021 for randomised controlled trials comparing second-line glucose lowering therapies with placebo, standard care or one another. Primary outcomes included cardiovascular and renal outcomes. Secondary outcomes were non-cardiovascular adverse events. Risk ratios (RRs) and corresponding confidence intervals (CI) or credible intervals (CrI) were reported within pairwise and network meta-analysis. The quality of evidence was evaluated using the GRADE (Grading of Recommendations, Assessment, Development and Evaluation) criteria. Number needed to treat (NNT) and number needed (NNH) to harm were calculated at 5 years using incidence rates and RRs. PROSPERO (CRD42020168322).

RESULTS

We included 38 trials from seven classes of glucose-lowering therapies. Both sodium-glucose co-transporter-2 inhibitors (SGLT2i) and glucagon-like peptide 1 receptor agonists (GLP1RA) showed moderate to high certainty in reducing risk of 3-point major adverse cardiovascular events, 3P-MACE (network estimates: SGLT2i [RR 0.90; 95% CrI 0.84-0.96; NNT, 59], GLP1RA [RR 0.88; 95% CrI 0.83-0.93; NNT, 50]), cardiovascular death, all-cause mortality, renal composite outcome and macroalbuminuria. SGLT2i also showed high certainty in reducing risk of hospitalization for heart failure (hHF), ESRD, acute kidney injury, doubling in serum creatinine and decline in eGFR. GLP1RA were associated with lower risk of stroke (high certainty) while glitazone use was associated with an increased risk of hHF (very low certainty). The risk of developing ESRD was lower with the use of sulphonylureas (low certainty). For adverse events, sulphonylureas and insulin were associated with increased hypoglycaemic events (very low to low certainty), while GLP1RA increased the risk of gastrointestinal side effects leading to treatment discontinuation (low certainty). DPP-4i increased risk of acute pancreatitis (low certainty). SGLT2i were associated with increased risk of genital infection, volume depletion (high certainty), amputation and ketoacidosis (moderate certainty). Risk of fracture was increased with the use of glitazones (moderate certainty).

CONCLUSIONS

SGLT2i and GLP1RA were associated with lower risk for different cardiorenal end points, when used as an adjunct to metformin in people with type 2 diabetes. Additionally, SGLT2i demonstrated benefits in reducing risk for surrogate end points in kidney disease progression. Safety outcomes differ among the available pharmacotherapies.

Potential effect of EGCG on the anti-tumor efficacy of metformin in melanoma cells

Metformin, a first-line drug for type 2 diabetes mellitus, has been recognized as a potential anti-tumor agent in recent years. Epigallocatechin-3-gallate (EGCG), as the dominant catechin in green tea, is another promising adjuvant agent for tumor prevention. In the present work, the potential effect of EGCG on the anti-tumor efficacy of metformin in a mouse melanoma cell line (B16F10) was investigated. Results indicated that EGCG and metformin exhibited a synergistic effect on cell viability, migration, and proliferation, as well as signal transducer and activator of transcription 3/nuclear factor-κB (STAT3/NF-κB) pathway signaling and the production of inflammation cytokines. Meanwhile, the combination showed an antagonistic effect on cell apoptosis and oxidative stress levels. The combination of EGCG and metformin also differentially affected the nucleus (synergism) and cytoplasm (antagonism) of B16F10 cells. Our findings provide new insight into the potential effects of EGCG on the anti-tumor efficacy of metformin in melanoma cells.

Glucagon-like peptide-1 receptor agonists and the cardiorenal axis in Type 2 diabetes: a focus on dulaglutide

Results from cardiovascular outcomes trials (CVOTs) in people with Type 2 diabetes (T2D), such as the Researching Cardiovascular Events with a Weekly Incretin in Diabetes (REWIND) study with dulaglutide, have led to a shift toward glucose lowering therapies that provide broad benefits, including cardiovascular (CV) risk reduction and renoprotection. Dulaglutide reduces atherosclerotic CV outcomes (hazard ratio 0.88; 95% CI: 0.79-0.99) and composite kidney outcomes (hazard ratio 0.85; 95% CI: 0.77-0.93) in people with T2D with high risk or established CV disease. The cardiologists' role has now expanded to include not only screening for T2D and treating risk factors, but also recommending or incorporating glucose-lowering agents with proven CV benefit into the care of their patients with T2D.