Effect of metformin on clinical, metabolic and endocrine outcomes in women with polycystic ovary syndrome: a meta-analysis of randomized controlled trials

Influence of metformin on hyperandrogenism in women with polycystic ovary syndrome: a systematic review and meta-analysis of randomized clinical trials

PURPOSE

To summarize the effects of metformin treatment on markers of hyperandrogenism in patients diagnosed with polycystic ovary syndrome (PCOS).

METHODS

A systematic review, with meta-analysis, of randomized placebo-controlled clinical trials that evaluated the effects of metformin treatment in adult patients with PCOS on the levels of hyperandrogenism markers was conducted. The literature search, data extraction, risk of bias, and the assessment of certainty of evidence were performed independently by two reviewers using a structured form. The results were combined by applying the random effect, and the effect measure presented as a standardized mean difference (SMD). Significant values were considered as p < 0.05 with 95% CI. Furthermore, sensitivity analyses were performed in order to explore possible heterogeneity between studies.

RESULTS

Were included 18 studies in the quantitative evaluation and 17 studies (23 reports) in the quantitative evaluation. A significant reduction in total testosterone levels was seen in the metformin-treated group when compared to the control group after combining the results by the sensitivity analysis [SMD: - 0.46 (95% CI: - 0.89 to - 0.02)]. Therefore, FAI values were also regulated by metformin treatment.

CONCLUSION

We showed that metformin proved to be effective in reducing total testosterone levels, and the same was observed for free androgen index (FAI) values-a measure influenced by testosterone levels. The protocol of this study was registered at Prospero (CRD42021235761).

Acetate circumvents impaired metabolic switch in skeletal muscle of letrozole-induced PCOS rat model by suppression of PDK4/NLRP3

OBJECTIVES

Endocrine disorders in women of childbearing age, including polycystic ovarian syndrome (PCOS), have been linked to skeletal muscle insulin resistance with multiple post-receptor intracellular defects, disrupting metabolic flexibility. Short-chain fatty acids, such as acetate have been suggested as a metabolic modulator. However, the effects of acetate on aberrant metabolic switch in skeletal muscle of individuals with PCOS are unknown. This study therefore hypothesized that acetate would circumvent impaired metabolic switch in the skeletal muscle of a letrozole-induced PCOS rat model, probably by suppression of PDK4/NLRP3.

METHODS

Eight-wk-old female Wistar rats were assigned into three groups (n = 6), which received vehicle, letrozole (1 mg/kg), and letrozole plus acetate (200 mg/kg), respectively. The administrations were done by oral gavage for 21 d. .

RESULTS

Animals with PCOS had insulin resistance, increased testosterone, and leptin, as well as decreased adiponectin level. Additionally, the skeletal muscle was also characterized with increased lipid deposition, malondialdehyde, inflammatory mediators (nuclear factor-κB and tumor necrosis factor-α), lactate dehydrogenase, lactate/pyruvate ratio, HDAC and PDK 4 with corresponding decrease in glycogen synthesis, glutathione and NrF2. Besides, immunohistochemical evaluation showed severe expression of inflammasome and apoptosis in PCOS animals. Nonetheless, supplementation with acetate significantly attenuated these perturbations.

CONCLUSIONS

The present results demonstrate aberrant metabolic switch in the skeletal muscle of PCOS animals, which is accompanied by excessive inflammation, oxidative stress and elevated levels of histone deacetylase and PDK4. The results suggested that histone deacetylase inhibitor, acetate circumvents impaired metabolic switch in the skeletal muscle of PCOS rats by suppression of PDK4/NLRP3 inflammasome.

The modifier effect of physical activity, body mass index, and age on the association of metformin and chronic back pain: A cross-sectional analysis of 21,899 participants from the UK Biobank

BACKGROUND

There is growing evidence of the anti-inflammatory effect of the anti-diabetic drug metformin and its use to reduce pain. However, we currently lack studies investigating whether metformin is associated with a reduction in chronic back pain prevalence when considering physical activity levels, body mass index (BMI), and age.

OBJECTIVE

To investigate whether use of metformin is associated with lower levels of reporting of chronic back pain in a large cohort with type 2 diabetes when stratified for physical activity, BMI, and age.

METHODS

This is a cross-sectional study of 21,889 participants with type 2 diabetes who were drawn from the UK Biobank database. We investigated whether people using metformin reported a higher prevalence of chronic low back pain than those who did not. Type 2 diabetes, chronic back pain, and metformin were self-reported. Participants were stratified according to their physical activity level (low, moderate and high), BMI (normal, overweight, and obese), and age (40 to <50; 50 to < 60; and ≥60 years). Logistic regression models were built for each physical activity level, BMI and age category to investigate the prevalence of chronic back pain amongst those using and not using metformin.

RESULTS

Participants who were using metformin and who had low levels of physical activity [OR 0.87, 95%CI 0.78 to 0.96] or who were obese [OR 0.90, 95%CI 0.86 to 0.98] or older [OR 0.85, 95%CI 0.78 to 0.93] had lower odds of reporting chronic back pain than their counterparts.

CONCLUSION

The anti-diabetic drug metformin might reduce prevalence of chronic low back pain in people who are older, overweight, or less active. These findings should be confirmed in studies using a longitudinal design.

Metformin improves polycystic ovary syndrome in mice by inhibiting ovarian ferroptosis

BACKGROUND AND OBJECTIVE

PCOS is a common metabolic disorder in women of reproductive age, which pathogenesis is very complex. The role of ferroptosis in PCOS is a novel finding, and the mechanistic studies are not clear. Metformin is a commonly used drug of PCOS but few studies on whether metformin can improve the follicle development and ovarian function in PCOS. We aims to use PCOS mouse model to study the effect of metformin on PCOS based on the ovarian function and explored the regulation of metformin in PCOS mice by intervening in ferroptosis pathway.

MATERIALS AND METHODS

C57 BL/6J female mice aged 4-5 weeks were purchased and gavaged with letrozole (1 mg/kg/day) combined with high-fat diet for 21days to establish PCOS model, and control group was set up. After modeling, the mice were divided into PCOS model group and metformin treatment group (Met) (n=6).The Met group were gavaged metformin (200 mg/kg/day) for 28 days. The body weight, estrous cycle, glucose tolerance test (OGTT)and insulin resistance test (ITT) were monitored. Then, The mice were euthanized to collect serum and ovaries. Elisa was used to detect changes in related serum hormones (E2, LH, FSH, TP). Ovaries used for molecular biology experiments to detect changes in GPX4, SIRT3, AMPK/p-AMPK, and mTOR/p-mTOR by Western blot and qPCR.

RESULTS

Compared with the model group mice, body weight was significantly reduced, and their estrous cycle was restored in Met group. The results of OGTT and ITT showed an improvment of glucose tolerance and insulin resistance. Morphological results showed that after metformin treatment, polycystic lesions in ovaries were reduced, the ovarian function was restored, and the expressions of SIRT3 and GPX4 were elevated. WB results demonstrated that the expressions of p-mTOR and p-AMPK in ovaries were significantly reduced in Model group, but reversed in MET group.

CONCLUSION

Our study confirmed metformin could not only improve body weight and metabolism disorders, but also improve ovarian dysfunction in PCOS mice.In addition, we explored metformin could regulate ferroptosis to improve PCOS via the SIRT3/AMPK/mTOR pathway. Our study complements the mechanisms by which metformin improves PCOS.

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

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

The effect of metformin treatment on leukocyte telomere length in patients with polycystic ovary syndrome: a prospective case-control study

PURPOSE

The study aimed to investigate the effect of metformin treatment on leukocyte telomere length (LTL) and the relationship of LTL with C-reactive protein (CRP), homocysteine, albumin, complete blood count, and HOMA-IR values in patients with polycystic ovary syndrome (PCOS).

MATERIAL AND METHOD

A prospective case-control study consisting of 30 women with PCOS and 30 healthy women without PCOS was performed. The relationship between clinical and laboratory parameters and LTL was analyzed. PCOS patients were treated with metformin (850 mg/day) for three months. Before treatment (BT) and after treatment (AT), each patient's LTL was evaluated and compared with the control group.

RESULTS

In the comparison between PCOS and control groups, the difference was significant for LTL, age, body mass index (BMI), and CRP (p = 0.002; p < 0.001; p = 0.001; p = 0.01, respectively). In PCOS patients, the difference between BT and AT, LTL was not statistically significant (BT: 6.06 ± 2.12; AT: 6.30 ± 1.93; p = 0.623; 95% C.I: - 1.22-0.74); however, the difference for weight was significant (BT: 83.78 ± 15.31; AT: 80.62 ± 15.40; p = 0.02; 95% CI: 1.34-4.99). The logistic regression model established by BMI (group 1: 21-24, group 2: 24-29, group 3: 29-34, group 4: > 34), age, and RDW, which predicted the PCOS group by affecting the LTL level, was statistically significant (p < 0.001/PPV = 96.3%; NPV = 88.5%). Each unit reduction in telomere length increased women's probability of PCOS by 0.4 times (p = 0.013; OR = 0.419, 95% CI: 0.211-0.835).

CONCLUSION

Although statistically insignificant, LTL increased after metformin use in PCOS patients, and the mean weight loss reduction was statistically significant. Telomere shortening increased the likelihood of PCOS 0.4 times.

Inhibition of Microtubule Affinity Regulating Kinase 4 by Metformin: Exploring the Neuroprotective Potential of Antidiabetic Drug through Spectroscopic and Computational Approaches

Microtubule affinity regulating kinase 4 (MARK4) regulates the mechanism of microtubules by its ability to phosphorylate the microtubule-associated proteins (MAP's). MARK4 is known for its major role in tau phosphorylation via phosphorylating Ser²⁶² residue in the KXGS motif, which results in the detachment of tau from microtubule. In lieu of this vital role in tau pathology, a hallmark of Alzheimer's disease (AD), MARK4 is a druggable target to treat AD and other neurodegenerative disorders (NDs). There is growing evidence that NDs and diabetes are connected with many pieces of literature demonstrating a high risk of developing AD in diabetic patients. Metformin (Mtf) has been a drug in use against type 2 diabetes mellitus (T2DM) for a long time; however, recent studies have established its therapeutic effect in neurodegenerative diseases (NDs), namely AD, Parkinson's disease (PD) and amnestic mild cognitive impairment. In this study, we have explored the MARK4 inhibitory potential of Mtf, employing in silico and in vitro approaches. Molecular docking demonstrated that Mtf binds to MARK4 with a significant affinity of -6.9 kcal/mol forming interactions with binding pocket's critical residues. Additionally, molecular dynamics (MD) simulation provided an atomistic insight into the binding of Mtf with MARK4. ATPase assay of MARK4 in the presence of Mtf shows that it inhibits MARK4 with an IC₅₀ = 7.05 µM. The results of the fluorescence binding assay demonstrated significant binding of MARK4 with a binding constant of 0.6 × 10⁶ M^-1. The present study provides an additional axis towards the utilization of Mtf as MARK4 inhibitor targeting diabetes with NDs.

The effect of metformin on low birth weight girls with precocious puberty: A protocol for systematic review and meta-analysis

BACKGROUND

In recent years, the role of metformin in girls with precocious puberty (PP) has been increasingly frequently studied. The objective of this present study is to assess the effect of metformin on low birth weight girls with precocious puberty (LBW-PP girls).

METHODS

We search the confirmed studies about circulating metformin and PP from the databases of EMBASE, PubMed, and Web of Science. Data were reported as weighted mean difference (WMD) and associated 95% confidence intervals (CIs). Analysis was performed by Review Manager 5.3 and Stata version 12.0.

RESULTS

A total of 205 cases (metformin group n = 102, untreated group n = 103) were included in this study. The meta-analysis of randomized controlled trials (RCTs) suggested that metformin had statistically significant effects on testosterone (P = .001), androstenedione (P = .022), bone mineral density (BMD; P = .151), triglycerides (P ≤ .001), body mass index Z score (BMI Z score; P ≤ .001), dehydroepiandrosterone-sulfate (DHEAS; P = .053), sex hormone-binding globulin (SHBG; P = .049), high-density lipoprotein (HDL) cholesterol (P ≤ .001), low-density lipoprotein (LDL) cholesterol (P = .021), fat mass (P ≤ .001), lean mass (P = .025), and fasting insulin (P = .002).

CONCLUSION

This meta-analysis provided evidence of the efficacy of metformin in girls with LBW-PP girls, which proved that metformin could improve metabolism and reduce weight. Metformin had a positive effect on preventing LBW-PP girls from developing into obesity and polycystic ovarian syndrome. In addition, this meta-analysis provided important reference opinions and directions for the treatment of LBW-PP girls.

The use of metformin in women with polycystic ovary syndrome: an updated review

PURPOSES

Polycystic ovary syndrome (PCOS) is a major cause of female infertility, being present in up to 20% of women of childbearing age. Insulin resistance (IR) plays an important role in the pathophysiology of PCOS; therefore, its treatment may benefit women with the syndrome. The main drug used for IR management is metformin (MT). We aim to review the literature on the use of metformin in women with PCOS.

METHODS

Using the terms "metformin" and "polycystic ovary syndrome," we conducted a search the PubMed, EMBASE, and Google Scholar databases. The research was restricted to articles published in English. Initially, only published meta-analyses were included, in the absence of meta-analyzes, RCT and well-designed prospective studies were used.

RESULTS

Metformin increases success rates and decreases complication rates when used as an adjunctive medication for ovulation induction during low complexity assisted reproduction treatments and during ovarian stimulation for in vitro fertilization in women with PCOS. Evidence about the effect of metformin on fetal and obstetric complication rates is conflicting. Metformin is associated with high incidence of gastrointestinal symptoms; however, serious adverse effects are rare and there is no evidence of teratogenicity.

CONCLUSION

For women with PCOS, metformin is a good adjunctive medication for ovulation induction/stimulation for high and low complexity assisted reproduction therapies. The adverse effects are mostly mild, and there is no risk of teratogenicity, but the risk of long-term complications for the offspring is not yet defined. High heterogeneity of the studies limits extrapolation of findings, and further research is needed to determine which women will benefit most from the medication.

Impact of pharmacological interventions on insulin resistance in women with polycystic ovary syndrome: A systematic review and meta-analysis of randomized controlled trials

OBJECTIVE

Polycystic ovary syndrome (PCOS) is a complex endocrine condition affecting women of reproductive age. It is characterized by insulin resistance and is a major risk factor for type 2 diabetes mellitus (T2DM). The objective was to review the literature on the effect of different pharmacological interventions on insulin resistance in women with PCOS.

DESIGN

We searched PubMed, MEDLINE, Scopus, Embase, Cochrane library and the Web of Science in April 2020 and updated in March 2021. The study follows the 2020 Preferred Reporting Items for Systematic reviews and Meta-ana. Reviwers extracted data and assessed the risk of bias using the Cochrane risk of bias tool.

RESULTS

In 58 randomized controlled trials there were significant reductions in the fasting blood glucose (FBG) with metformin versus placebo (standardized mean difference [SMD]: -0.23; 95% confidence interval [CI]: -0.40, -0.06; I² = 0%, low-grade evidence), and acarbose versus metformin (mean difference [MD]: -10.50 mg/dl; 95% CI: -15.76, -5.24; I² = 0%, low-grade evidence). Significant reductions in fasting insulin (FI) with pioglitazone versus placebo (SMD: -0.55; 95% CI: -1.03, -0.07; I² = 37%; p = .02, very-low-grade evidence). A significant reduction in homoeostatic model assessment of insulin resistance (HOMA-IR) was seen with exenatide versus metformin (MD: -0.34; 95% CI: -0.65, -0.03; I² = 0%, low-grade evidence). No effect on homoeostatic model assessment of beta cells (HOMA-B) was observed.

CONCLUSIONS

Pharmacological interventions, including metformin, acarbose, pioglitazone and exenatide have significant effects on FBG, FI, HOMA-IR but not on HOMA-B.

Metformin serum concentrations during pregnancy and postpartum - a clinical study in patients with polycystic ovary syndrome

Background and objectives

Metformin is used to treat gestational diabetes. It is also used to treat women with polycystic ovary syndrome and has been shown to prevent late miscarriage and preterm birth. However, increased renal clearance during pregnancy causes a decline in serum concentrations of metformin. The aim of this study was to explore the time course of the pregnancy‐related changes in metformin pharmacokinetics and the return to the non‐pregnant state.

Method

A subgroup of women in the PregMet2 study (n = 73) agreed to provide serum samples at three time‐points in pregnancy (gestational weeks 19, 28 and 32) and once in post partum, (either 2, 4 or 8 weeks after delivery). Serum metformin concentrations were compared using a four‐parameter logistic model.

Findings

The mean steady‐state serum concentration of metformin during pregnancy was 9.39 μmoL/L, whereas the post partum concentration was 12.36 μmoL/L, an increase of 32% (p = 0,019). This change took place already during the first 2 weeks post partum.

Conclusion

Clinicians who treat pregnant women with metformin should be aware of the significant decrease in metformin concentration mediated by pregnancy, and the rapid increase after delivery, as it may impact both the therapeutic efficacy and the risk of adverse drug reactions.

Effects of Metformin and Exercise in Polycystic Ovary Syndrome: Systematic Review and Meta-Analysis

Polycystic ovary syndrome (PCOS) is a common endocrine disorder in women of reproductive age. Metformin is introduced for treatment of women with PCOS, and the beneficial effects of exercise in women with PCOS are found for a range of outcomes. Our aim is to compare the effects of metformin plus exercise with exercise intervention in PCOS on clinical, anthropometric, metabolic, and psychological parameters. MEDLINE, EMBASE, Web of Science and China National Knowledge Infrastructure were searched for studies. Nine studies were considered eligible for inclusion. The meta-analysis reveals that metformin offers additive benefits to exercise, leading to modest improvements in menstrual cycles, hyperandrogenism, and abdominal fat.

Autophagy Modulators in Cancer Therapy

Autophagy is a process of self-degradation that plays an important role in removing damaged proteins, organelles or cellular fragments from the cell. Under stressful conditions such as hypoxia, nutrient deficiency or chemotherapy, this process can also become the strategy for cell survival. Autophagy can be nonselective or selective in removing specific organelles, ribosomes, and protein aggregates, although the complete mechanisms that regulate aspects of selective autophagy are not fully understood. This review summarizes the most recent research into understanding the different types and mechanisms of autophagy. The relationship between apoptosis and autophagy on the level of molecular regulation of the expression of selected proteins such as p53, Bcl-2/Beclin 1, p62, Atg proteins, and caspases was discussed. Intensive studies have revealed a whole range of novel compounds with an anticancer activity that inhibit or activate regulatory pathways involved in autophagy. We focused on the presentation of compounds strongly affecting the autophagy process, with particular emphasis on those that are undergoing clinical and preclinical cancer research. Moreover, the target points, adverse effects and therapeutic schemes of autophagy inhibitors and activators are presented.

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.

The effects of metformin on autophagy

Metformin is the first-line option for treating newly diagnosed diabetic patients and also involved in other pharmacological actions, including antitumor effect, anti-aging effect, polycystic ovarian syndrome prevention, cardiovascular action, and neuroprotective effect, etc. However, the mechanisms of metformin actions were not fully illuminated. Recently, increasing researches showed that autophagy is a vital medium of metformin playing pharmacological actions. Nevertheless, results on the effects of metformin on autophagy were inconsistent. Apart from few clinical evidences, more data focused on kinds of no-clinical models. First, many studies showed that metformin could induce autophagy via a number of signaling pathways, including AMPK-related signaling pathways (e.g. AMPK/mTOR, AMPK/CEBPD, MiTF/TFE, AMPK/ULK1, and AMPK/miR-221), Redd1/mTOR, STAT, SIRT, Na⁺/H⁺ exchangers, MAPK/ERK, PK2/PKR/AKT/ GSK3β, and TRIB3. Secondly, some signaling pathways were involved in the process of metformin inhibiting autophagy, such as AMPK-related signaling pathways (AMPK/NF-κB and other undetermined AMPK-related signaling pathways), Hedgehog, miR-570-3p, miR-142-3p, and MiR-3127-5p. Thirdly, two types of signaling pathways including PI3K/AKT/mTOR and endoplasmic reticulum (ER) stress could bidirectionally impact the effectiveness of metformin on autophagy. Finally, multiple signal pathways were reviewed collectively in terms of affecting the effectiveness of metformin on autophagy. The pharmacological effects of metformin combining its actions on autophagy were also discussed. It would help better apply metformin to treat diseases in term of mediating autophagy.

Constitutive Androstane Receptor-Mediated Inhibition of Metformin on Phase II Metabolic Enzyme SULT2A1

BACKGROUND

Metformin, as a first-line treatment for diabetes, interacts with many protein kinases and transcription factors which affect the expression of downstream target genes governing drug metabolism. Sulfotransferase, SULT2A1, one phase II metabolic enzyme, sulfonates both xenobiotic and endobiotic compounds to accelerate drug excretion. Herein, we designed experiments to investigate the effects and mechanisms of metformin on SULT2A1 expression in vitro.

METHODS

The hepatocellular carcinoma cell line, HepaRG, was cultured with different concentrations of metformin. The cell viability was measured using CCK8 kit. HepaRG was used to evaluate the protein expression of pregnane X receptor (PXR), the constitutive androstane receptor (CAR), SULT2A1, AMP-activated protein kinase (AMPK), and phosphorylation of AMPK (p-AMPK), respectively, at different concentrations of metformin with or without rifampin (human PXR activator) and CITCO (human CAR activator). The coregulators with CAR on SULT2A1 promoter response elements have also been characterized.

RESULTS

We showed that metformin did not affect the basic expression of SULT2A1 but could suppress the expression of SULT2A1 induced by the activator of human CAR. Investigations revealed that metformin which could block CAR nuclear translocation further suppress SULT2A1. In addition, we found that the prevented CAR transfer into the nucleus by metformin was partially an AMPK-dependent event.

CONCLUSION

The present study indicated that the activation of AMPK-CAR pathway mediated the suppression of SULT2A1 by metformin. Metformin may affect the metabolism and clearance of drugs which are SULT2A1 substrates. The results that emerged from this work provide substantial insights into an appropriate medication in the treatment of diabetes patients.

Effects of metformin on blood lipid profiles in nondiabetic adults: a meta-analysis of randomized controlled trials

PURPOSE

To evaluate the effects of metformin on serum lipid profiles in nondiabetic adults through a comprehensive meta-analysis.

METHODS

In the present meta-analysis, randomized and controlled trials were collected by searching PubMed, Embase, and Cochrane Libraries from inception to April 2019. Compared with placebos, the effects of metformin treatment on lipid profiles in nondiabetic adults were evaluated.

RESULTS

Forty-seven studies from 45 articles including 5731 participants were enrolled. Pooled results showed that metformin had significant effects on total cholesterol (mean change -6.57 mg/dl; 95% CI -9.66, -3.47; P = 0.000) and LDL-c (mean change -4.69 mg/dl; 95% CI -7.38, -2.00; P = 0.001), but insignificant effects on HDL-c (mean change -4.33 mg/dl; 95% CI -9.62, 0.96; P = 0.109) and triglyceride (mean change -0.85 mg/dl; 95% CI -0.36, 2.06; P = 0.169). Significant heterogeneities were found for all lipid profiles (HDL-c = 85.5%; LDL-c = 59.9%; total cholesterol = 75.3% and triglyceride = 67.1%). Different from the pooled data, in a subgroup analysis, the effect of metformin on triglyceride in patients with polycystic ovarian syndrome (PCOS) was significant with a mean reduction of 8.15 mg/dl. In addition, sensitivity analysis showed that the pooled effects of metformin on serum lipid profiles were stable. Publication bias derived from funnel plots or Begg's tests (P = 0.933, 0.860, 0.904, and 0.567 for HDL-c, LDL-c, total cholesterol, and triglyceride, respectively) was not significant.

CONCLUSION

This meta-analysis revealed that metformin could reduce total cholesterol and LDL-c in nondiabetic adults. In addition, metformin might exert a triglyceride-lowering effect in nondiabetics with PCOS status.

GDF-15 as a Weight Watcher for Diabetic and Non-Diabetic People Treated With Metformin

Weight gain and obesity are global health concerns contributing to morbidity with increased risks of cardiovascular disease, diabetes, liver steatohepatitis and cancer. Pharmacological therapies or bariatric surgery are often required for those who fail to adhere to diet and lifestyle modifications. Metformin, a widely used antidiabetic agent, seems to have a health benefit beyond its anti-hyperglycemic properties, with few side effects. Emerging evidence shows weight loss to be associated with metformin in both diabetic and non-diabetic individuals. Recently, the growth differentiation factor 15 (GDF-15), a member of the transforming growth factor beta superfamily, has been identified as a key mediator of metformin-induced weight loss. Metformin increases the secretion of GDF-15, which binds exclusively to glial cell-derived neurotrophic factor family receptor alpha-like (GFRAL). This gut-brain cytokine works as a prominent player in reducing food intake and body weight in health and disease, like anorexia nervosa and cancer. Herein, we critically review advances in the understanding of the weight-reducing effects of metformin via the GDF-15 pathway.

From Prediabetes to Type 2 Diabetes Mellitus in Women with Polycystic Ovary Syndrome: Lifestyle and Pharmacological Management

AIMS

Despite the very clear association between polycystic ovary syndrome (PCOS) and dysglycemia, few studies have explored the continuum of glycemic alterations leading from minor glucose abnormalities to overt diabetes. The purpose of this review is to trace the natural history of glycemic alteration in women with PCOS.

METHODS

We performed a literature review without time limit until August 2019. Inclusion criteria were studies addressing the association between impaired glucose tolerance or impaired fasting glucose or type 2 diabetes (T2D) and PCOS with at least an English abstract. The exclusion criteria were no PCOS or impaired glucose tolerance or impaired fasting glucose or T2D as outcome. The outcomes of interest were the onset of impaired glucose tolerance, impaired fasting glucose, T2D, and the progression from impaired glucose tolerance or impaired fasting glucose to T2D.

RESULTS

Healthy diet and physical activity are the first-line therapy for PCOS. Treatment with metformin was associated with significant lower 2-hour postload glucose levels and with reduction in fasting glucose when compared to placebo. Thiazolidinediones were more effective in reducing fasting glucose levels compared to placebo. Metformin and pioglitazone treatments showed similar effects on fasting glucose levels. The sodium-glucose cotransporter-2 inhibitor empagliflozin did not show differences in metabolic parameters when compared to metformin. The combination therapy with metformin plus the glucagon-like peptide-1 receptor agonist liraglutide was associated with significant improvements in basal and postload glucose levels compared with only liraglutide. Likewise, a combination therapy with the dipeptidyl peptidase-4 inhibitor saxagliptin and metformin demonstrated superiority versus metformin in fasting glucose and oral glucose tolerance test normalization. Myo-inositol supplementation was associated with lower insulin levels, glucose levels, and insulin resistance when compared with placebo, metformin, or estrogen treatments.

CONCLUSIONS

The use of insulin-sensitizing agents, such as metformin and inositols, along with lifestyle interventions may improve the metabolic profile in PCOS women.

l-Carnitine plus metformin in clomiphene-resistant obese PCOS women, reproductive and metabolic effects: a randomized clinical trial

To evaluate the reproductive and metabolic effects of L-carnitine plus metformin in clomiphene citrate (CC) resistant obese polycystic ovary syndrome (PCOS) women. A double-blinded randomized controlled clinical trial, clomiphene-citrate resistant obese women were allocated randomly to receive CC plus metformin and L-carnitine (n = 138) or CC plus metformin and placebo (n = 136). The primary outcome was clinical pregnancy rate. The secondary outcomes were hormonal and metabolic profile changes in addition to ovulation and first trimester (13 weeks) miscarriage rates. Clomiphene-citrate, L-carnitine, and metformin group showed significant improvement in the menstrual regularity, ovulation rate, and pregnancy rate compared to CC plus metformin and placebo group (29% vs. 9%, 34.7% vs.11%, and 28.2% vs. 6.6%, respectively). No statistically significant difference in the miscarriage rate between the two groups (p = .08). After three months of treatment, the reduction in body mass index (BMI) was non-significant (p = .061) between both groups. The hormonal and metabolic parameters were more significantly improved in the L-carnitine group compared with the placebo group. l-Carnitine may act synergistically with metformin for improvement of reproductive performance, insulin resistance, and lipid profile in clomiphene-resistant obese PCOS women.

Health Benefits of Anti-aging Drugs

Aging, as a physiological process mediated by numerous regulatory pathways and transcription factors, is manifested by continuous progressive functional decline and increasing risk of chronic diseases. There is an increasing interest to identify pharmacological agents for treatment and prevention of age-related disease in humans. Animal models play an important role in identification and testing of anti-aging compounds; this step is crucial before the drug will enter human clinical trial or will be introduced to human medicine. One of the main goals of animal studies is better understanding of mechanistic targets, therapeutic implications and side-effects of the drug, which may be later translated into humans. In this chapter, we summarized the effects of different drugs reported to extend the lifespan in model organisms from round worms to rodents. Resveratrol, rapamycin, metformin and aspirin, showing effectiveness in model organism life- and healthspan extension mainly target the master regulators of aging such as mTOR, FOXO and PGC1α, affecting autophagy, inflammation and oxidative stress. In humans, these drugs were demonstrated to reduce inflammation, prevent CVD, and slow down the functional decline in certain organs. Additionally, potential anti-aging pharmacologic agents inhibit cancerogenesis, interfering with certain aspects of cell metabolism, proliferation, angioneogenesis and apoptosis.

Effects of empagliflozin on metabolic parameters in polycystic ovary syndrome: A randomized controlled study

BACKGROUND

Empagliflozin is a sodium-glucose-cotransporter-2 inhibitor that improves cardiovascular risk and promotes weight loss in patients with type-2 diabetes. Polycystic ovary syndrome (PCOS) is associated with obesity and increased cardiovascular risk; therefore, empagliflozin may be of benefit for these women. The aim of this study was to compare the effects of empagliflozin vs metformin on anthropometric and body composition, hormonal and metabolic parameters in women with PCOS.

MATERIALS AND METHODS

A randomized open-label study was conducted in women with PCOS who were randomized to either empagliflozin 25 mg (n = 19) or metformin 1500 mg (n = 20) daily for 12 weeks. The main outcomes assessed were changes in anthropometric and body composition, hormonal and metabolic parameters.

RESULTS

Univariate analysis showed significant differences in weight (empagliflozin: -1.4 ± 3.2% vs metformin: 1.2 ± 2.3%; P = 0.006), body mass index (empagliflozin: -1.4 ± 3.2% vs metformin: 1.1 ± 2.2%; P = 0.006), waist circumference (empagliflozin: -1.6 ± 2.8% vs metformin: 0.2 ± 2.1%; P = 0.029) and hip circumference (empagliflozin: -2.0 ± 3.0% vs metformin: 1.1 ± 1.9%; P = 0.001), basal metabolic rate (empagliflozin: -1.8 ± 2.9% vs metformin: 0.1 ± 1.9%, P = 0.024) and fat mass (empagliflozin: -0.7 ± 4.9% vs metformin, 3.2 ± 5.0%; P = 0.023) between the empagliflozin and the metformin groups. These differences were confirmed in linear regression analysis after adjustment for relevant covariates. There were no significant changes in hormonal or metabolic parameters between both groups.

CONCLUSION

There was a significant improvement in anthropometric parameters and body composition, in overweight and obese women with PCOS after 12 weeks of treatment with empagliflozin compared to metformin, although no changes were seen in hormonal or metabolic parameters.

Pharmacological and surgical treatment of nonreproductive outcomes in polycystic ovary syndrome: An overview of systematic reviews

BACKGROUND

Polycystic ovary syndrome (PCOS) affects up to 13% women and is associated with significant complications. The quality of evidence supporting the recommendations on treatment of nonreproductive outcomes in PCOS is unknown.

OBJECTIVE

To summarize and appraise the methodological quality of systematic reviews and meta-analyses evaluating pharmacological and surgical treatments for nonreproductive outcomes in PCOS.

METHODS

A literature search from MEDLINE, EMBASE, CINAHL PLUS and PROSPERO was performed from inception until 15th of September 2017. Article selection, data extraction and quality appraisal of included reviews were performed in duplicate. A narrative synthesis of the findings was conducted.

RESULTS

This overview included 31 reviews. The quality was low for 7 (23%), moderate for sixteen (52%) and high for 8 reviews (26%). Two reviews assessed psychological outcomes. Metformin improved anthropometric (7 of 10 reviews), metabolic (4 of 14 reviews) and endocrine outcomes (3 of twelve reviews). Thiazolidinediones improved metabolic (2 of 5 reviews) and endocrine outcomes (one of 5 reviews) but worsened weight gain (5 of 5 reviews). Combined oral contraceptive pill (COCP) improved clinical hyperandrogenism (2 of 2 reviews). Statins improved lipid profile (3 of 3 reviews) and testosterone level (2 of 3 reviews). There was no conclusive evidence from included systematic reviews regarding the use of other interventions.

CONCLUSIONS

There is reliable evidence regarding the use of metformin for anthropometric outcomes and COCPs for hyperandrogenism in women with PCOS but not for other interventions. There is significant gap in knowledge regarding the management of psychological outcomes in women with PCOS which needs further evaluation.

Cardiometabolic risk in polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a common disorder in women of reproductive age. Besides hyperandrogenism, oligomenorrhea and fertility issues, it is associated with a high prevalence of metabolic disorders and cardiovascular risk factors. Several genetic polymorphisms have been identified for possible associations with cardiometabolic derangements in PCOS. Different PCOS phenotypes differ significantly in their cardiometabolic risk, which worsens with severity of androgen excess. Due to methodological difficulties, longer time-scale data about cardiovascular morbidity and mortality in PCOS and about possible beneficial effects of different treatment interventions is missing leaving many issues regarding cardiovascular risk unresolved.

Effect of resveratrol and metformin on ovarian reserve and ultrastructure in PCOS: an experimental study

Background

PCOS is a reproductive hormonal abnormality and a metabolic disorder. It is frequently associated with insulin resistance, hyperandrogenism, chronic inflammation, and oxidative stress. We aim to investigate the potential therapeutic effects of combined therapy of resveratrol and metformin on polycystic ovaries via SIRT1 and AMPK activation.

Methods

Wistar albino rats were divided into control and experimental (PCOS) groups. DHEA-induced PCOS rats were given resveratrol (20 mg/kg/day), metformin (300 mg/kg/day) and combined therapy. At the end of the experiment, the body and ovarian weight of rats were measured and blood samples were analyzed for FSH, LH, testosterone, AMH, TNF-α and MDA levels. Histopathological evaluation of ovaries were carried out by light and electron microscopy. SIRT1 and AMPK immunreactivity and TUNEL assay were scored. Data were statistically analyzed by SPSS programme.

Results

Metformin and combined treatment groups reduced the body and ovary weights compared to the PCOS group. Serum testosterone levels were significantly higher in the PCOS group than in the control group and this was reduced when PCOS was treated with all but especially resveratrol. All the treatment groups decreased LH, LH/FSH, TNF-α and tissue AMH levels which were induced in the PCOS group, whereas metformin was unable to improve the increased MDA and plasma AMH levels. Treatment with resveratrol and/or metformin ameliorated the elevated number of secondary and atretic follicles and the decreased number of Graafian follicles in the PCOS group, which indicates the effect of the treatments on the maintenance of folliculogenesis. Light and electron microscopic findings supported the analysis of follicular count. Increased number of TUNEL (+) granulosa cells in the PCOS group were reduced significantly in the treatment groups. Resveratrol and metformin increased SIRT1 and AMPK immunreactivity, respectively, compared to the PCOS group.

Conclusions

The results suggest that combined therapy of metformin and resveratrol may improve the weight gain, hormone profile and ovarian follicular cell architecture by inducing antioxidant and antiinflammatory systems via SIRT1 and AMPK activation in PCOS.

Lactate-Induced Glucose Output Is Unchanged by Metformin at a Therapeutic Concentration - A Mass Spectrometry Imaging Study of the Perfused Rat Liver

Metformin is the first line drug for type 2 diabetes but its molecular mechanisms remain unclear. Here, we have studied the acute effect of a therapeutically relevant intrahepatic concentration of metformin on glucose production from lactate. We selected the perfused rat liver as experimental system since it enables the complete control of drug dosage. We used MALDI (matrix-assisted laser desorption/ionization) mass spectrometry imaging to estimate the concentration of metformin in the livers and we measured the concentration of glucose in the effluent medium under basal conditions and following lactate addition. MALDI mass spectra of thin-sections of freeze-clamped rat liver perfused with metformin showed a peak at 130.16 m/z which was unambiguously assigned to metformin. The mass spectrometric detection limit was at a tissue concentration of about 250 nM, and uptake of metformin from the perfusion medium to the liver occurred with a K_m of 0.44 mM. Metformin was evenly distributed in the liver irrespective of its concentration in the perfusion medium and the duration of a perfusion. At a parenchymal concentration of 30 μM, metformin did not induce any significant suppression of the basal or lactate-induced glucose release from the liver. These results show that matrix-assisted laser desorption/ionization mass spectrometry imaging can be applied to estimate the tissue concentration and distribution of metformin in a therapeutically relevant micromolar concentration range. Our findings challenge the view that metformin causes an inhibition of glucose release from the liver by an acute inhibition of mitochondrial glycerol 3-phosphate dehydrogenase (EC 1.1.5.3).

Metformin: a review of its potential indications

Metformin is the most commonly prescribed drug for type 2 diabetes mellitus. In recent years, in addition to glucose lowering, several studies have presented evidence suggesting some potential role for metformin, such as antitumor effect, antiaging effect, cardiovascular protective effect, neuroprotective effect or an optional treatment for polycystic ovary syndrome. This paper will critically review the role of metformin to provide reference for doctors and researchers.