Metformin and gut microbiota: their interactions and their impact on diabetes

The crosstalk between gut microbiota, intestinal immunological niche and visceral adipose tissue as a new model for the pathogenesis of metabolic and inflammatory diseases: the paradigm of type 2 diabetes mellitus

Gut microbiota (GM) comprises more than one thousand microorganisms between bacterial species, viruses, fungi, and protozoa, and represents the main actor of a wide net of molecular interactions, involving, among others, the endocrine system, immune responses, and metabolism. GM influences many endocrine functions such as adrenal steroidogenesis, thyroid function, sexual hormones, IGF-1 pathway and peptides produced in gastrointestinal system. It is fundamental in glycaemic control and obesity, while also exerting an important function in modulating the immune system and associated inflammatory disease. The result of this crosstalk in gut mucosa is the formation of the intestinal immunological niche. Visceral adipose tissue (VAT) produces about 600 different peptides, it is involved in lipid and glucose metabolism and in some immune reactions through several adipokines. GM and VAT interact in a bidirectional fashion: while gut dysbiosis can modify VAT adipokines and hormone secretion, VAT hyperplasia modifies GM composition. Acquired or genetic factors leading to gut dysbiosis or increasing VAT (i.e., Western diet) induce a proinflammatory condition, which plays a pivotal role in the development of dysmetabolic and immunologic conditions, such as diabetes mellitus. Diabetes is clearly associated with specific patterns of GM alterations, with an abundance or reduction of GM species involved in controlling mucosal barrier status, glycaemic levels and exerting a pro- or anti-inflammatory activity. All these factors could explain the higher incidence of several inflammatory conditions in Western countries; furthermore, besides the specific alterations observed in diabetes, this paradigm could represent a common pathway acting in many metabolic conditions and could pave the way to a new, interesting therapeutic approach.

Metformin treatment of juvenile mice alters aging-related developmental and metabolic phenotypes

Accumulating evidence suggests that the influence on developmental traits might have long-term effects on aging and health later in life. Metformin is a widely used drug for treating type 2 diabetes and is also used for delaying sexual maturation in girls with precocious puberty. The current report focuses on investigating the effects of metformin on development and metabolic traits. Heterogeneous mice (UM-HET3) were treated with i.p. metformin between the ages of 15 and 56 days. Our results show that body weight and food consumption were increased in both sexes, and sexual maturation was delayed in females. Tail length and circulating insulin-like growth factor 1 (IGF1) levels were significantly increased in both sexes. No significant difference was found in insulin tolerance test, but glucose tolerance was significantly reduced in the males. Circulating adiponectin and insulin levels were altered by metformin treatment in a sex-specific manner. Analysis of quantitative insulin sensitivity check index (QUICKI) suggests that metformin treatment increased insulin sensitivity in female pups, but had opposite effect in male pups. This study revealed that early life metformin treatment alters development and metabolism of mice in both sex-specific and non-specific manners. These effects of metformin may have long-term impacts on aging-related traits.

Pharmacomicrobiomics in Western Medicine and Traditional Chinese Medicine in Type 2 Diabetes

Pharmacomicrobiomics refers to the interactions between foreign compounds and the gut microbiome resulting in heterogeneous efficacy, side effects, and toxicity of the compound concerned. Glucose lowering drugs reduce blood glucose by modulating insulin secretion and its actions as well as redistributing energy disposal. Apart from genetic, ecological, and lifestyle factors, maintaining an equilibrium of the whole gut microbiome has been shown to improve human health. Microbial fingerprinting using faecal samples indicated an 'invisible phenotype' due to different compositions of microbiota which might orchestrate the interactions between patients' phenotypes and their responses to glucose-lowering drugs. In this article, we summarize the current evidence on differences in composition of gut microbiota between individuals with type 2 diabetes (T2D) and healthy individuals, the disruption of the balance of beneficial and pathogenic microbiota was shown in patients with T2D and how Western Medicine (WM) and Traditional Chinese Medicine (TCM) might re-shape the gut microbiota with benefits to the host immunity and metabolic health. We particularly highlighted the effects of both WM and TCM increase the relative abundance of health promoting bacteria, such as, Akkermansia muciniphila, Blautia, and Bifidobacterium adolescentis, and which have been implicated in type 2 diabetes (T2D). Several lines of evidence suggested that TCM might complement the efficacy of WM through alteration of microbiota which warrants further investigation in our pursuit of prevention and control of T2D.

Characterization of the gut microbiota among Veterans with unique military-related exposures and high prevalence of chronic health conditions: A United States-Veteran Microbiome Project (US-VMP) study

The gut microbiome is impacted by environmental exposures and has been implicated in many physical and mental health conditions, including anxiety disorders, affective disorders, and trauma- and stressor-related disorders such as posttraumatic stress disorder (PTSD). United States (US) military Veterans are a unique population in that their military-related exposures can have consequences for both physical and mental health, but the gut microbiome of this population has been understudied. In this publication, we describe exposures, health conditions, and medication use of Veterans in the US Veteran Microbiome Project (US-VMP) and examine the associations between these characteristics and the gut microbiota. This cohort included 331 US Veterans seeking healthcare with the Veterans Health Administration who were 83% male with an average (±SD) age of 47.6 ​± ​13.4 years. The cohort displayed a high prevalence of PTSD (49.8%) and history of traumatic brain injuries (76.1%), and high current use of prescription medications (74.9%) to treat various acute and chronic conditions. We observed significant associations between the gut microbiota composition and gastroenteritis, peripheral vascular disease (PVD), bipolar disorders, symptoms of severe depression based on the Beck Depression Inventory, stimulant and opioid use disorders, beta-blockers, serotonin and norepinephrine reuptake inhibitor antidepressants, diabetes medications, and proton pump inhibitors. Many of the Veteran characteristics examined were associated with altered relative abundances of specific taxa. We found that PVD and cardiovascular disease were associated with lower microbiota diversity in the gut (i.e., α-diversity), while supplemental vitamin use was associated with higher α-diversity. Our study contributes novel insights as to whether the unique exposures of Veterans in this cohort correlate with gut microbiota characteristics and, in line with previous findings with other population-level studies of the microbiome, confirms associations between numerous health conditions and medications with the gut microbiome.

The effects of diabetes mellitus on clinical outcomes of hospitalized patients with acute diverticulitis

OBJECTIVES

Acute diverticulitis is a common gastrointestinal illness due to diverticular inflammation and focal necrosis. Diabetes mellitus has been reported to influence the outcomes of patients with diverticular disease. Our study aimed to examine the inpatient outcomes and complications of patients with acute diverticulitis and coexisting diabetes mellitus.

METHODS

The Nationwide Inpatient Sample was used to identify adult patients in 2014 admitted for acute diverticulitis. Primary outcomes were mortality, length of stay (LOS), and total hospitalization charges. Secondary outcomes were complications of acute diverticulitis and interventions.

RESULTS

In total, 44 330 of patients with acute diverticulitis and diabetes mellitus were included in the analysis. Acute diverticulitis patients with diabetes mellitus had a higher rate of diverticular bleeding (P < 0.0001), but lower rates of abscess (P < 0.0001), obstruction (P < 0.0001) and colectomy (P < 0.0001) when compared to acute diverticulitis patients without diabetes mellitus. Complicated diabetes mellitus was associated with a longer LOS (P = 0.00003) and greater total hospitalization charges (P = 0.0021) compared to uncomplicated diabetes mellitus when coexisting with acute diverticulitis.

CONCLUSIONS

Acute diverticulitis with diabetes mellitus is associated with a higher rate of diverticular bleeding, lower rates of abscess, obstruction, and colectomy compared to acute diverticulitis without diabetes mellitus. When coexisting with acute diverticulitis, complicated diabetes mellitus is not associated with higher rates of mortality or diverticulitis-related complications compared to uncomplicated diabetes mellitus.

Berberine combined with stachyose improves glycometabolism and gut microbiota through regulating colonic microRNA and gene expression in diabetic rats

AIMS

Berberine is effective for type 2 diabetes mellitus (T2DM), but has limited use in clinic. This study aims to evaluate the effect of berberine combined with stachyose on glycolipid metabolism and gut microbiota and to explore the underlying mechanisms in diabetic rats.

MAIN METHODS

Zucker diabetic fatty (ZDF) rats were orally administered berberine, stachyose and berberine combined with stachyose once daily for 69 days. The oral glucose tolerance and levels of blood glucose, insulin, triglyceride and total cholesterol were determined. The gut microbial profile, colonic miRNA and gene expression were assayed using Illumina sequencing. The quantitative polymerase chain reaction was used to verify the expression of differentially expressed miRNAs and genes.

KEY FINDINGS

Repeated treatments with berberine alone and combined with stachyose significantly reduced the blood glucose, improved the impaired glucose tolerance, and increased the abundance of beneficial Akkermansiaceae, decreased that of pathogenic Enterobacteriaceae in ZDF rats. Furthermore, combined treatment remarkably decreased the abundances of Desulfovibrionaceae and Proteobacteria in comparison to berberine. Combined treatment evidently decreased the expression of intestinal early growth response protein 1 (Egr1) and heparin-binding EGF-like growth factor (Hbegf), and significantly increased the expression of miR-10a-5p, but berberine alone not.

SIGNIFICANCE

Berberine combined with stachyose significantly improved glucose metabolism and reshaped gut microbiota in ZDF rats, especially decreased the abundance of pathogenic Desulfovibrionaceae and Proteobacteria compared to berberine alone, providing a novel strategy for treating T2DM. The underlying mechanisms may be associated with regulating the expression of intestinal Egr1, Hbegf and miR-10a-5p, but remains further elucidation.

Gut Microbiota in Adipose Tissue Dysfunction Induced Cardiovascular Disease: Role as a Metabolic Organ

The gut microbiome has emerged as a key regulator of host metabolism. Accumulating evidence has indicated that the gut microbiota is involved in the development of various human diseases. This association relies on the structure and metabolites of the gut microbiota. The gut microbiota metabolizes the diet ingested by the host into a series of metabolites, including short chain fatty acids, secondary bile acids, trimethylamine N-oxide, and branched-chain amino acids, which affects the physiological processes of the host by activating numerous signaling pathways. In this review, we first summarize the various mechanisms through which the gut microbiota influences adipose tissue dysfunction and metabolic processes that subsequently cause cardiovascular diseases, highlighting the complex interactions between gut microbes, their metabolites, and the metabolic activity of the host. Furthermore, we investigated the current status of clinical therapies for adipose tissue dysfunction directed at the gut microbiota. Finally, we discuss the challenges that remain to be addressed before this field of research can be translated to everyday clinical practice.

Gut microbiota as the critical correlation of polycystic ovary syndrome and type 2 diabetes mellitus

Gut microbiota forms a symbiotic relationship with the host and maintains the ecological balance of the internal and external environment of the human body. However, dysbiosis of the gut microbiota and immune deficiency, as well as environmental changes, can destroy the host-microbial balance, leading to the occurrence of a variety of diseases, such as polycystic ovary syndrome (PCOS), type 2 diabetes mellitus (T2DM), and obesity. Meanwhile, diseases can also affect gut microbiota, forming a vicious cycle. The role of the intestinal microbiota in different diseases have been proven by several studies; however, as a common target of PCOS and T2DM, there are few reports on the treatment of different diseases through the regulation of intestinal microbiota as the critical correlation. This review analyzed the common mechanisms of intestinal microbiota in PCOS and T2DM, including the dysbiosis of gut microbiota, endotoxemia, short-chain fatty acids, biotransformation of bile acids, and synthesis of amino acid in regulating insulin resistance, obesity, chronic inflammation, and mitochondrial dysfunction. The possible therapeutic effects of probiotics and/or prebiotics, fecal microbiota transplantation, bariatric surgery, dietary intervention, drug treatment, and other treatments targeted at regulating intestinal microbiota were also elucidated.

Human Microbiota Network: Unveiling Potential Crosstalk between the Different Microbiota Ecosystems and Their Role in Health and Disease

The human body is host to a large number of microorganisms which conform the human microbiota, that is known to play an important role in health and disease. Although most of the microorganisms that coexist with us are located in the gut, microbial cells present in other locations (like skin, respiratory tract, genitourinary tract, and the vaginal zone in women) also play a significant role regulating host health. The fact that there are different kinds of microbiota in different body areas does not mean they are independent. It is plausible that connection exist, and different studies have shown that the microbiota present in different zones of the human body has the capability of communicating through secondary metabolites. In this sense, dysbiosis in one body compartment may negatively affect distal areas and contribute to the development of diseases. Accordingly, it could be hypothesized that the whole set of microbial cells that inhabit the human body form a system, and the dialogue between the different host microbiotas may be a contributing factor for the susceptibility to developing diseased states. For this reason, the present review aims to integrate the available literature on the relationship between the different human microbiotas and understand how changes in the microbiota in one body region can influence other microbiota communities in a bidirectional process. The findings suggest that the different microbiotas may act in a coordinated way to decisively influence human well-being. This new integrative paradigm opens new insights in the microbiota field of research and its relationship with human health that should be taken into account in future studies.

The Gut Microbiome, Metformin, and Aging

Metformin has been extensively used for the treatment of type 2 diabetes, and it may also promote healthy aging. Despite its widespread use and versatility, metformin's mechanisms of action remain elusive. The gut typically harbors thousands of bacterial species, and as the concentration of metformin is much higher in the gut as compared to plasma, it is plausible that microbiome-drug-host interactions may influence the functions of metformin. Detrimental perturbations in the aging gut microbiome lead to the activation of the innate immune response concomitant with chronic low-grade inflammation. With the effectiveness of metformin in diabetes and antiaging varying among individuals, there is reason to believe that the gut microbiome plays a role in the efficacy of metformin. Metformin has been implicated in the promotion and maintenance of a healthy gut microbiome and reduces many age-related degenerative pathologies. Mechanistic understanding of metformin in the promotion of a healthy gut microbiome and aging will require a systems-level approach. Expected final online publication date for the Annual Review of Pharmacology and Toxicology, Volume 62 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Influence of immunomodulatory drugs on the gut microbiota

Immunomodulatory medications are a mainstay of treatment for autoimmune diseases and malignancies. In addition to their direct effects on immune cells, these medications also impact the gut microbiota. Drug-induced shifts in commensal microbes can lead to indirect but important changes in the immune response. We performed a comprehensive literature search focusing on immunotherapy/microbe interactions. Immunotherapies were categorized into 5 subtypes based on their mechanisms of action: cell trafficking inhibitors, immune checkpoint inhibitors, immunomodulators, antiproliferative drugs, and inflammatory cytokine inhibitors. Although no consistent relationships were observed between types of immunotherapy and microbiota, most immunotherapies were associated with shifts in specific colonizing bacterial taxa. The relationships between colonizing microbes and drug efficacy were not well-studied for autoimmune diseases. In contrast, the efficacy of immune checkpoint inhibitors for cancer was tied to the baseline composition of the gut microbiota. There was a paucity of high-quality data; existing data were generated using heterogeneous sampling and analytic techniques, and most studies involved small numbers of participants. Further work is needed to elucidate the extent and clinical significance of immunotherapy effects on the human microbiome.

Sex- and Gender-Based Pharmacological Response to Drugs

In humans, the combination of all sex-specific genetic, epigenetic, and hormonal influences of biologic sex produces different in vivo environments for male and female cells. We dissect how these influences of sex modify the pharmacokinetics and pharmacodynamics of multiple drugs and provide examples for common drugs acting on specific organ systems. We also discuss how gender of physicians and patients may influence the therapeutic response to drugs. We aim to highlight sex as a genetic modifier of the pharmacological response to drugs, which should be considered as a necessary step toward precision medicine that will benefit men and women. SIGNIFICANCE STATEMENT: This study discusses the influences of biologic sex on the pharmacokinetics and pharmacodynamics of drugs and provides examples for common drugs acting on specific organ systems. This study also discusses how gender of physicians and patients influence the therapeutic response to drugs.

The Relationship between the Gut Microbiome and Metformin as a Key for Treating Type 2 Diabetes Mellitus

Metformin is the first-line pharmacotherapy for treating type 2 diabetes mellitus (T2DM); however, its mechanism of modulating glucose metabolism is elusive. Recent advances have identified the gut as a potential target of metformin. As patients with metabolic disorders exhibit dysbiosis, the gut microbiome has garnered interest as a potential target for metabolic disease. Henceforth, studies have focused on unraveling the relationship of metabolic disorders with the human gut microbiome. According to various metagenome studies, gut dysbiosis is evident in T2DM patients. Besides this, alterations in the gut microbiome were also observed in the metformin-treated T2DM patients compared to the non-treated T2DM patients. Thus, several studies on rodents have suggested potential mechanisms interacting with the gut microbiome, including regulation of glucose metabolism, an increase in short-chain fatty acids, strengthening intestinal permeability against lipopolysaccharides, modulating the immune response, and interaction with bile acids. Furthermore, human studies have demonstrated evidence substantiating the hypotheses based on rodent studies. This review discusses the current knowledge of how metformin modulates T2DM with respect to the gut microbiome and discusses the prospect of harnessing this mechanism in treating T2DM.

Anti-Aging Effect of Metformin: A Molecular and Therapeutical Perspective

Aging is a time-dependent inevitable process, in which cellular homeostasis is affected, which has an impact on tissue function. This represents a risk factor for the development of numerous non-transmissible diseases. In consequence, the scientific community continues to search for therapeutic measures capable of improving quality of life and delaying cellular aging. At the center of this research is metformin, a widely used drug in Type 2 Diabetes Mellitus treatment that has a reduced adverse effects profile. Furthermore, there is evidence that this drug has beneficial health effects that go beyond its anti-hyperglycemic properties. Among these effects, its geronto-protection capability stands out. There is growing evidence that points out to an increased life expectancy as well as the quality of life in model organisms treated with metformin. Therefore, there is an abundance of research centered on elucidating the mechanism through which metformin has its anti-aging effects. Among these, the AMPK, mTORC1, SIRT1, FOXO, NF.kB, and DICER1 pathways can be mentioned. Furthermore, studies have highlighted the possibility of a role for the gut microbiome in these processes. The next step is the design of clinical essays that have as a goal evaluating the efficacy and safety of metformin as an anti-aging drug in humans to create a paradigm in the medical horizon. The question being if metformin is, in fact, the new antiaging therapy in humans?

The Current and Potential Therapeutic Use of Metformin-The Good Old Drug

Metformin, one of the oldest oral antidiabetic agents and still recommended by almost all current guidelines as the first-line treatment for type 2 diabetes mellitus (T2DM), has become the medication with steadily increasing potential therapeutic indications. A broad spectrum of experimental and clinical studies showed that metformin has a pleiotropic activity and favorable effect in different pathological conditions, including prediabetes, type 1 diabetes mellitus (T1DM) and gestational diabetes mellitus (GDM). Moreover, there are numerous studies, meta-analyses and population studies indicating that metformin is safe and well tolerated and may be associated with cardioprotective and nephroprotective effect. Recently, it has also been reported in some studies, but not all, that metformin, besides improvement of glucose homeostasis, may possibly reduce the risk of cancer development, inhibit the incidence of neurodegenerative disease and prolong the lifespan. This paper presents some arguments supporting the initiation of metformin in patients with newly diagnosed T2DM, especially those without cardiovascular risk factors or without established cardiovascular disease or advanced kidney insufficiency at the time of new guidelines favoring new drugs with pleotropic effects complimentary to glucose control. Moreover, it focuses on the potential beneficial effects of metformin in patients with T2DM and coexisting chronic diseases.

New Horizons in Microbiota and Metabolic Health Research

Decade-old studies have demonstrated that microbes living in our gut (microbiota) contribute to both maintaining normal metabolic function and to the pathology of metabolic diseases, such as obesity and diabetes. Emerging evidence suggests that gut microbiota influences the personalized effects of diets and drugs and impact the gut-brain axis and leaky gut inflammation to control metabolic function/diseases. Gut microbiota can be an ideal source of prognostic markers and therapies for metabolic diseases. Here we discuss the emerging concepts in the area of microbiota and metabolic interactions in personalized nutrition, drug response, and disease prognosis.

Metformin Use Is Associated with a Lower Risk of Inflammatory Bowel Disease in Patients with Type 2 Diabetes Mellitus

AIM

Our aim was to compare the risk of developing inflammatory bowel disease [IBD] between ever users and never users of metformin.

METHODS

Patients with newly diagnosed type 2 diabetes mellitus from 1999 to 2005 were enrolled from Taiwan's National Health Insurance. A total of 340 211 ever users and 24 478 never users who were free from IBD on January 1, 2006 were followed up until December 31, 2011. Hazard ratios were estimated by Cox regression incorporating the inverse probability of treatment weighting using a propensity score.

RESULTS

New-onset IBD was diagnosed in 6466 ever users and 750 never users. The respective incidence rates were 412.0 and 741.3 per 100 000 person-years and the hazard ratio for ever vs never users was 0.55 [95% confidence interval: 0.51-0.60]. A dose-response pattern was observed while comparing the tertiles of cumulative duration of metformin therapy to never users. The respective hazard ratios for the first [<26.0 months], second [26.0-58.3 months] and third [>58.3 months] tertiles were 1.00 [0.93-1.09], 0.57 [0.52-0.62] and 0.24 [0.22-0.26]. While patients treated with oral antidiabetic drugs [OADs] without metformin were treated as a reference group, the hazard ratios for patients treated with OADs with metformin, with insulin without metformin [with/without other OADs] and with insulin and metformin [with/without other OADs] were 0.52 [0.42-0.66], 0.95 [0.76-1.20] and 0.50 [0.40-0.62], respectively.

CONCLUSION

A reduced risk of IBD is consistently observed in patients with type 2 diabetes mellitus who have been treated with metformin.

Should metformin remain the first-line therapy for treatment of type 2 diabetes?

Metformin is a biguanide that is used as first-line treatment of type 2 diabetes mellitus and is effective as monotherapy and in combination with other glucose-lowering medications. It is generally well-tolerated with minimal side effects and is affordable. Although the safety and efficacy of metformin have been well-established, there is discussion regarding whether metformin should continue to be the first choice for therapy as other anti-hyperglycemic medications exhibit additional advantages in certain populations. Despite a long-standing history of metformin use, there are limited cardiovascular outcomes data for metformin. Furthermore, the available studies fail to provide strong evidence due to either small sample size or short duration. Recent data from glucagon-like peptide-1 receptor agonist and sodium-glucose cotransporter-2 inhibitor cardiovascular and renal outcomes trials demonstrated additional protection from diabetes complications for some high-risk patients, which has impacted the guidelines for diabetes management. Post-hoc analyses comparing hazard ratios for participants taking metformin at baseline versus not taking metformin are inconclusive for these two groups. There are no data to suggest that metformin should not be initiated soon after the diagnosis of diabetes. Furthermore, the initiation of newer glycemic-lowering medications with cardiovascular benefits should be considered in high-risk patients regardless of glycemic control or target HbA1c. However, cost remains a major factor in determining appropriate treatment.

The Association of Targeted Gut Microbiota with Body Composition in Type 2 Diabetes Mellitus

The association between body composition and gut microbiota in type 2 diabetes mellitus (DM) remains unknown. To elucidate the correlation of body composition and gut microbiota, we conducted a clinical study to enroll 179 patients with type 2 DM. Body composition of lean tissue index (LTI) and fat tissue index was measured by Body Composition Monitor. Eight pairs of 16S rRNA gene primers specific to Firmicutes, Bacteroidetes, the Clostridium leptum group, Bacteroides, Bifidobacterium, Akkermansia muciniphila, Escherichia coli, and Faecalibacterium prausnitzii were used to measure their abundance by quantitative polymerase chain reaction. The results showed that type 2 DM with higher abundance of phylum Firmicutes and a higher ratio of phyla Firmicutes to Bacteroidetes (phyla F/B ratio) had higher LTI. This significant correlation between phyla F/B ratio and LTI was especially evident in type 2 DM with high body mass index, and independent of glycemic control or dipeptidyl peptidase-4 inhibitor usage. In conclusion, our study demonstrated the positive association of LTI with the abundance of phylum Firmicutes and the phyla F/B ratio in type 2 DM.

A Critical Review of the Evidence That Metformin Is a Putative Anti-Aging Drug That Enhances Healthspan and Extends Lifespan

The numerous beneficial health outcomes associated with the use of metformin to treat patients with type 2 diabetes (T2DM), together with data from pre-clinical studies in animals including the nematode, C. elegans, and mice have prompted investigations into whether metformin has therapeutic utility as an anti-aging drug that may also extend lifespan. Indeed, clinical trials, including the MILES (Metformin In Longevity Study) and TAME (Targeting Aging with Metformin), have been designed to assess the potential benefits of metformin as an anti-aging drug. Preliminary analysis of results from MILES indicate that metformin may induce anti-aging transcriptional changes; however it remains controversial as to whether metformin is protective in those subjects free of disease. Furthermore, despite clinical use for over 60 years as an anti-diabetic drug, the cellular mechanisms by which metformin exerts either its actions remain unclear. In this review, we have critically evaluated the literature that has investigated the effects of metformin on aging, healthspan and lifespan in humans as well as other species. In preparing this review, particular attention has been placed on the strength and reproducibility of data and quality of the study protocols with respect to the pharmacokinetic and pharmacodynamic properties of metformin. We conclude that despite data in support of anti-aging benefits, the evidence that metformin increases lifespan remains controversial. However, via its ability to reduce early mortality associated with various diseases, including diabetes, cardiovascular disease, cognitive decline and cancer, metformin can improve healthspan thereby extending the period of life spent in good health. Based on the available evidence we conclude that the beneficial effects of metformin on aging and healthspan are primarily indirect via its effects on cellular metabolism and result from its anti-hyperglycemic action, enhancing insulin sensitivity, reduction of oxidative stress and protective effects on the endothelium and vascular function.

Hydrochlorothiazide and Indapamide bind the NADPH binding site of bacterial Dihydrofolate Reductase: results of an in-silico study and their implications

Hypertension is a public health concern. Low dose thiazide diuretics are known to effectively control blood pressure compared to that of other classes of antihypertensive drugs. In this context, we have performed an in-silico study and found that the two Sulphonamide Diuretics Hydrochlorothiazide and Indapamide bound the NADPH binding region of bacterial Dihydrofolate Reductase. Therefore, akin to Sulphonamide Antibiotics, Sulphonamide Diuretics may have antibiotic activity and thereby have the potential to modulate the gut microbiome in a way beneficial to vascular health. The in-silico experiment results were analyzed in the context of the relevant literature. We postulate that Sulphonamide Diuretics exert their antihypertensive role by modulating the gut microbiome, specifically by increasing butyrate-producing taxa in the gut. We recommend extending such work as it is plausible that Indapamide and other Sulphonamide Diuretics may be beneficial for both diabetes and hypertension.

Microbiota and Diabetes Mellitus: Role of Lipid Mediators

Diabetes Mellitus (DM) is an inflammatory clinical entity with different mechanisms involved in its physiopathology. Among these, the dysfunction of the gut microbiota stands out. Currently, it is understood that lipid products derived from the gut microbiota are capable of interacting with cells from the immune system and have an immunomodulatory effect. In the presence of dysbiosis, the concentration of lipopolysaccharides (LPS) increases, favoring damage to the intestinal barrier. Furthermore, a pro-inflammatory environment prevails, and a state of insulin resistance and hyperglycemia is present. Conversely, during eubiosis, the production of short-chain fatty acids (SCFA) is fundamental for the maintenance of the integrity of the intestinal barrier as well as for immunogenic tolerance and appetite/satiety perception, leading to a protective effect. Additionally, it has been demonstrated that alterations or dysregulation of the gut microbiota can be reversed by modifying the eating habits of the patients or with the administration of prebiotics, probiotics, and symbiotics. Similarly, different studies have demonstrated that drugs like Metformin are capable of modifying the composition of the gut microbiota, promoting changes in the biosynthesis of LPS, and the metabolism of SCFA.

Lactobacillus rhamnosus GG and HbA1c in middle age and older adults without type 2 diabetes mellitus: A preliminary randomized study

BACKGROUND AND AIMS

Probiotic supplementation improves glycemic control in persons with diabetes and the current study examined whether these benefits extend to healthy individuals.

METHODS

The current study was a 90-day placebo-controlled, double-blind, randomized clinical trial of Lactobacillus rhamnosus GG in healthy middle-aged and older adults. Fasting blood glucose and HbA1c were quantified at baseline and follow up.

RESULTS

ANCOVA controlling for baseline values showed group differences in follow up HbA1c [F (1,90) = 8.44, p = 0.005]; HbA1c values increased in the placebo group, though remained stable in the probiotic group.

CONCLUSIONS

If replicated, Lactobacillus rhamnosus GG may protect against changes in glycemic control.

NAFLD and increased risk of cardiovascular disease: clinical associations, pathophysiological mechanisms and pharmacological implications

Non-alcoholic fatty liver disease (NAFLD) is a public health problem, affecting up to a third of the world's adult population. Several cohort studies have consistently documented that NAFLD (especially in its more advanced forms) is associated with a higher risk of all-cause mortality and that the leading causes of death among patients with NAFLD are cardiovascular diseases (CVDs), followed by extrahepatic malignancies and liver-related complications. A growing body of evidence also indicates that NAFLD is strongly associated with an increased risk of major CVD events and other cardiac complications (ie, cardiomyopathy, cardiac valvular calcification and cardiac arrhythmias), independently of traditional cardiovascular risk factors. This narrative review provides an overview of the literature on: (1) the evidence for an association between NAFLD and increased risk of cardiovascular, cardiac and arrhythmic complications, (2) the putative pathophysiological mechanisms linking NAFLD to CVD and other cardiac complications and (3) the current pharmacological treatments for NAFLD that might also benefit or adversely affect risk of CVD.

Whole-blood transcriptome profiling reveals signatures of metformin and its therapeutic response

Metformin, a biguanide agent, is the first-line treatment for type 2 diabetes mellitus due to its glucose-lowering effect. Despite its wide application in the treatment of multiple health conditions, the glycemic response to metformin is highly variable, emphasizing the need for reliable biomarkers. We chose the RNA-Seq-based comparative transcriptomics approach to evaluate the systemic effect of metformin and highlight potential predictive biomarkers of metformin response in drug-naïve volunteers with type 2 diabetes in vivo. The longitudinal blood-derived transcriptome analysis revealed metformin-induced differential expression of novel and previously described genes involved in cholesterol homeostasis (SLC46A1 and LRP1), cancer development (CYP1B1, STAB1, CCR2, TMEM176B), and immune responses (CD14, CD163) after administration of metformin for three months. We demonstrate for the first time a transcriptome-based molecular discrimination between metformin responders (delta HbA1c ≥ 1% or 12.6 mmol/mol) and non-responders (delta HbA1c < 1% or 12.6 mmol/mol), that is determined by expression levels of 56 genes, explaining 13.9% of the variance in the therapeutic efficacy of the drug. Moreover, we found a significant upregulation of IRS2 gene (log₂FC 0.89) in responders compared to non-responders before the use of metformin. Finally, we provide evidence for the mitochondrial respiratory complex I as one of the factors related to the high variability of the therapeutic response to metformin in patients with type 2 diabetes mellitus.

Gut microbiota and diabetes: From correlation to causality and mechanism

In this review, we summarize the recent microbiome studies related to diabetes disease and discuss the key findings that show the early emerging potential causal roles for diabetes. On a global scale, diabetes causes a significant negative impact to the health status of human populations. This review covers type 1 diabetes and type 2 diabetes. We examine promising studies which lead to a better understanding of the potential mechanism of microbiota in diabetes diseases. It appears that the human oral and gut microbiota are deeply interdigitated with diabetes. It is that simple. Recent studies of the human microbiome are capturing the attention of scientists and healthcare practitioners worldwide by focusing on the interplay of gut microbiome and diabetes. These studies focus on the role and the potential impact of intestinal microflora in diabetes. We paint a clear picture of how strongly microbes are linked and associated, both positively and negatively, with the fundamental and essential parts of diabetes in humans. The microflora seems to have an endless capacity to impact and transform diabetes. We conclude that there is clear and growing evidence of a close relationship between the microbiota and diabetes and this is worthy of future investments and research efforts.

The consequences of altered microbiota in immune-related chronic kidney disease

The normal gut microbiome modulates host enterocyte metabolism and shapes local and systemic immunity. Accumulation of urea and other waste products in chronic kidney disease induces gut dysbiosis and intestinal wall inflammation (leaky gut). There are decreased numbers of bacteria that generate short-chain fatty acids, which are an important nutrient source for host enterocytes and also contribute to regulation of the host immune system. Anaerobic proteolytic bacteria that express urease, uricase and indole and p-cresol enzymes, such as Enterobacteria and Enterococci, are increased. Microbial-derived uremic toxins such as indoxyl sulfate and trimethylamine N-oxide contribute to the pathophysiology of immune-related kidney diseases such as diabetic nephropathy, lupus nephritis and immunoglobulin A (IgA) nephropathy. Animal and clinical studies suggest potential benefits of dietary and probiotic interventions in slowing the progression of immune-related kidney diseases.

Hypoglycemic Effect of Ginsenoside Rg5 Mediated Partly by Modulating Gut Microbiota Dysbiosis in Diabetic db/db Mice

In this study, we aimed to investigate the influence of ginsenoside Rg5 (Rg5) on gut microbiota in diabetic db/db mice. Our data indicated that Rg5 not only improved the symptoms of hyperglycemia, repaired intestinal barrier function, and relieved metabolic endotoxemia-related inflammation but also reversed gut microbiota dysbiosis in the colon with significantly decreased Firmicutes/Bacteroidetes ratios. More importantly, the effects of Rg5 were further confirmed by partial changes in the gut microbiota induced by broad-spectrum antibiotics. These findings indicated that Rg5 dramatically decreased the abundance of Firmicutes and Verrucomicrobia at the phylum level and increased the abundance of Bacteroidetes and Proteobacteria in diabetic db/db mice. Altogether, our findings, for the first time, demonstrate that Rg5 may be used as a beneficial probiotic agent that reverses gut microbiota dysbiosis and diabetes-associated metabolic disorders in the context of type 2 diabetes mellitus.

Considering gut microbiota in treatment of type 2 diabetes mellitus

Advances in the understanding of the pathogenesis of type 2 diabetes mellitus (T2D) have revealed a role for gut microbiota dysbiosis in driving this disease. This suggests the possibility that approaches to restore a healthy host-microbiota relationship might be a means of ameliorating T2D. Indeed, recent studies indicate that many currently used treatments for T2D are reported to impact gut microbiota composition. Such changes in gut microbiota may mediate and/or reflect the efficacy of these interventions. This article outlines the rationale for considering the microbiota as a central determent of development of T2D and, moreover, reviews evidence that impacting microbiota might be germane to amelioration of T2D, both in terms of understanding mechanisms that mediate efficacy of exiting T2D therapies and in developing novel treatments for this disorder.

Diabetes and Sarcopenic Obesity: Pathogenesis, Diagnosis, and Treatments

Sarcopenic obesity and diabetes are two increasing health problems worldwide, which both share many common risk factors, such as aging, and general obesity. The pathogenesis of sarcopenic obesity includes aging, physical inactivity, malnutrition, low-grade inflammation, insulin resistance, and hormonal changes. Nevertheless, there are two major reasons to cause diabetes: impaired insulin secretion and impaired insulin action. Furthermore, the individual diagnosis of obesity and sarcopenia should be combined to adequately define sarcopenic obesity. Also, the diagnosis of diabetes includes fasting plasma glucose test (FPG), 2-h oral glucose tolerance test (OGTT), glycated hemoglobin (A1C), and random plasma glucose coupled with symptoms. Healthy diet and physical activity are beneficial to both sarcopenic obesity and diabetes, but there are only recommended drugs for diabetes. This review consolidates and discusses the latest research in pathogenesis, diagnosis, and treatments of diabetes and sarcopenic obesity.