Metformin decreases plasma resistin concentrations in pediatric patients with impaired glucose tolerance: a placebo-controlled randomized clinical trial

The effect of metformin on adipokines levels: A systematic review and meta-analysis of randomized-controlled trials

BACKGROUND

Considering the role of adipokine on diseases related to metabolic syndrome and even chronic diseases, it seems necessary to investigate effective interventions on these factors. This study aimed to comprehensively investigate the effects of metformin on adipokines.

METHODS

A comprehensive search was conducted in five databases using established keywords. The purpose of this search was to uncover controlled studies that have examined the impact of metformin on adipokines, specifically leptin, adiponectin, and resistin. The random-effects model analysis was used to provide pooled weighted mean difference and 95% confidence intervals.

RESULTS

Forty-nine studies were included in this article. The pooled findings showed that that the administration of metformin significantly decreases leptin (WMD: -3.06 ng/ml, 95 % CI: -3.81, -2.30, P < 0.001) and resistin (WMD: -1.27 µg/mL, 95 % CI: -2.22, -0.31, P = 0.009) levels in different populations compared to the control group. However, no significant effect of this antidiabetic drug on adiponectin levels was reported. The results obtained from the subgroup results in the present study also showed that metformin in people with a BMI greater than 30 kg/m2 compared to a BMI ≤ 30 kg/m2 causes a significant decrease in leptin levels and an increase in adiponectin levels. Also, metformin in lower doses (≤1500 mg/day) and younger people (<30 years) causes a significant increase in adiponectin levels.

CONCLUSIONS

In general, considering the role of adipokines on metabolic disease and even chronic disease, this drug can be used as a potentially useful drug, especially in obese people, to improve these factors.

The Progression of Prediabetes to Type 2 Diabetes in Children and Adolescents in the United States: Current Challenges and Solutions

Prediabetes, the precursor of type 2 diabetes (T2D), is on the rise among children and adolescents in the United States. The natural history of prediabetes is poorly characterized in children compared to adults. The available data indicate a phenotype of an accelerated β-cell failure in youth with prediabetes. Data from randomized controlled trials showed no benefit on β-cell preservation or A1c in youth with prediabetes from therapeutic agents such as metformin and insulin. As a result, the American Diabetes Association recommends only lifestyle intervention, but not therapeutic agents, for the management of prediabetes in children and adolescents. These recommendations for lifestyle modification in youth, largely derived from data in adults, lack the precision necessary for efficacy in youth. However, a recent 4-year real-world study on youth reported that adherence to nutrition visits was associated with a 4-fold reduction in the likelihood of progressing from prediabetes to T2D. The finding that this reversal is associated with reduced insulin resistance (IR) and not with decreased body weight is novel and provides the foundation for trialing investigational products that may protect β-cells and reduce IR and/or body weight. This study provides the much-needed foundation for further exploration of the impact of lifestyle modification in conjunction with other approaches for the reversal of prediabetes in youth. The systematization of the protocol for medical nutrition therapy for the reversal of prediabetes in youth will ensure optimal and consistent results from adherent patients. This communication provides updates on the pathobiology of prediabetes in youth and a clear direction for efficacious studies in the field.

Cross-translational models of late-onset cognitive sequelae and their treatment in pediatric brain tumor survivors

Pediatric brain tumor treatments have a high success rate, but survivors are at risk of cognitive sequelae that impact long-term quality of life. We summarize recent clinical and animal model research addressing pathogenesis or evaluating candidate interventions for treatment-induced cognitive sequelae. Assayed interventions encompass a broad range of approaches, including modifications to radiotherapy, modulation of immune response, prevention of treatment-induced cell loss or promotion of cell renewal, manipulation of neuronal signaling, and lifestyle/environmental adjustments. We further emphasize the potential of neuroimaging as a key component of cross-translation to contextualize laboratory research within broader clinical findings. This cross-translational approach has the potential to accelerate discovery to improve pediatric cancer survivors' long-term quality of life.

The adolescent with obesity: what perspectives for treatment?

The dramatic increase in overweight and obesity among children and adolescents has become a major public health problem. Obesity in children and young adults is associated with an increased prevalence of cardiometabolic risk factors. Obesity during adolescence represents a strong predictor of obesity and higher mortality in adulthood. Due to the serious implications of obesity in adolescents, effective treatments are urgently needed. Lifestyle interventions represent the recommended therapy. Nevertheless, real world data show that the majority of adolescents do not achieve weight loss in the long term, and are reluctant to participate in lifestyle interventions. Pharmacological treatment is recommended if a formal lifestyle modification program fails to limit weight gain or to improve comorbidities. However, until 2020 the European Medicines Agency (EMA) had not approved any pharmacotherapeutic agents for obesity in pediatric patients. On April 2021, EMA has authorized the use of Liraglutide, a glucagon-like peptide (GLP)-1 analog, for the treatment of obesity in adolescents (12–17 years). The efficacy and safety of Liraglutide were demonstrated in a randomized, double-blind trial, enrolling 251 adolescents. After 56 weeks, a reduction in BMI of at least 5% was observed in 43.3% of participants in the liraglutide group vs. 18.7% in the placebo group, and a reduction in BMI of at least 10% was observed in 26.1 and 8.1%, respectively. Gastrointestinal events were the events most frequently reported with liraglutide. Bariatric surgery represents another effective treatment for adolescents with severe obesity, with sustained benefits on weight loss and cardiometabolic risk factors. However, long-term safety and effectiveness data in adolescents are still scarce. Risks of bariatric surgery include the need for additional abdominal surgical procedures and specific micronutrient deficiencies. Hopefully, new pharmacological treatments in addition to lifestyle interventions will offer more chances of success.

Metformin therapy in pediatric type 2 diabetes mellitus and its comorbidities: A review

Type 2 diabetes (T2D) rates in children and adolescents are rising globally. T2D is a complex and aggressive disease in children with several comorbidities, high treatment failure rates, and insulin needs within a few years from diagnosis. While myriads of pharmacotherapies are licensed to treat adults with T2D, treatments accessible to children and adolescents have been limited until recently. Metformin is an old drug with multiple beneficial metabolic health effects beyond glycemic control. This review discusses Metformin's origins, its mechanisms of action, and evidence for its use in the pediatric population to treat and prevent T2D. We also explore the evidence for its use as an obesity therapy, which is the primary driver of T2D, and T2D-driven comorbidities. While emerging therapies create new horizons for managing pediatric T2D, Metformin remains an inexpensive and safe part of the treatment plans of many T2D children globally for its beneficial metabolic effects.

Analysis of Time Course and Dose Effect From Metformin on Body Mass Index in Children and Adolescents

The purpose of this study was to analyze the time course and dose effect from metformin on body mass index (BMI) in children and adolescents by model-based meta-analysis (MBMA). Searching randomized controlled trial (RCT) studies of metformin on BMI in children and adolescents. The change rates of BMI from baseline values were used as indicator of evaluating metformin efficacy. A total of 18 RCT studies, 1,228 children and adolescents, were included for analysis, including patients with obesity, patients with type 1 diabetes mellitus, patients with nonalcoholic fatty liver, and patients with precocity. In order to achieve better effect of metformin on BMI in children and adolescents, the present study recommended that for patients with obesity, 1,000 mg/day metformin was required for at least 15.2 weeks and 60.8 weeks to achieve the plateau of metformin effect; for patients with type 1 diabetes mellitus, 1,000 mg/day metformin was required for at least 25.2 weeks and 100.8 weeks to achieve the plateau of metformin effect; for patients with nonalcoholic fatty liver, 1,000 mg/day metformin was required for at least 6.57 weeks and 26.28 weeks to achieve the plateau of metformin effect; for patients with precocity, 425 mg/day metformin was required for at least 12.4 weeks and 49.6 weeks to achieve the plateau of metformin effect. It was the first time to analyze the time course and dose effect from metformin on BMI and to recommend dosage and duration of treatment for metformin in children and adolescents with different disease types.

Efficacy and Safety of Metformin for Obesity: A Systematic Review

CONTEXT

The efficacy and safety of metformin for obesity in children and adolescents remains unclear.

OBJECTIVE

To assess the efficacy and safety of metformin via systematic review.

DATA SOURCES

Data sources included PubMed, Embase, the Cochrane Library, Scopus, and ClincalTrials.gov (inception to November 2019).

STUDY SELECTION

We selected randomized controlled trials (RCTs) in which researchers assessed the efficacy and safety of metformin with lifestyle interventions, compared with a placebo with lifestyle interventions, in children and adolescents with obesity.

DATA EXTRACTION

Two researchers independently extracted data and assessed quality. The primary outcomes were mean changes from baseline in BMI, BMI z score, homeostatic model assessment of insulin resistance, and gastrointestinal adverse effects.

RESULTS

Twenty-four RCTs (1623 patients; range: 16 to 151) were included. Ages ranged from 4 to 19 years, and follow-up ranged from 2 months to 2 years. Metformin resulted in a modest decrease in BMI (range of mean values: -2.70 to 1.30 vs -1.12 to 1.90), BMI z score (range of mean values: -0.37 to -0.03 vs -0.22 to 0.15), and homeostatic model assessment of insulin resistance (range of mean values: -3.74 to 1.00 vs -1.40 to 2.66). Metformin resulted in a higher frequency of gastrointestinal adverse effects (range: 2% to 74% vs 0% to 42%).

LIMITATIONS

The available evidence is of varying quality, with high heterogeneity between trials, suggesting some uncertainty in the benefits of metformin in this population.

CONCLUSIONS

With this systematic review of RCTs, we suggest that metformin has modest but favorable effects on weight and insulin resistance and a tolerable safety profile among children and adolescents with obesity.

Metformin as adjunctive therapy for dengue in overweight and obese patients: a protocol for an open-label clinical trial (MeDO)

Background:  Dengue is a disease of major global importance. While most symptomatic infections are mild, a small proportion of patients progress to severe disease with risk of hypovolaemic shock, organ dysfunction and death.  In the absence of effective antiviral or disease modifying drugs, clinical management is solely reliant on supportive measures. Obesity is a growing problem among young people in Vietnam and is increasingly recognised as an important risk factor for severe dengue, likely due to alterations in host immune and inflammatory pathways. Metformin, a widely used anti-hyperglycaemic agent with excellent safety profile, has demonstrated potential as a dengue therapeutic in vitro and in a retrospective observational study of adult dengue patients with type 2 diabetes.  This study aims to assess the safety and tolerability of metformin treatment in overweight and obese dengue patients, and investigate its effects on several clinical, immunological and virological markers of disease severity. Methods: This open label trial of 120 obese/overweight dengue patients will be performed in two phases, with a metformin dose escalation if no safety concerns arise in phase one. The primary endpoint is identification of clinical and laboratory adverse events.  Sixty overweight and obese dengue patients aged 10-30 years will be enrolled at the Hospital for Tropical Diseases in Ho Chi Minh City, Vietnam. Participants will complete a 5-day course of metformin therapy and be compared to a non-treated group of 60 age-matched overweight and obese dengue patients. Discussion:  Previously observed antiviral and immunomodulatory effects of metformin make it a promising dengue therapeutic candidate in appropriately selected patients. This study will assess the safety and tolerability of adjunctive metformin in the management of overweight and obese young dengue patients, as well as its effects on markers of viral replication, endothelial dysfunction and host immune responses.  Trial registration: ClinicalTrials.gov: NCT04377451 (May 6 th 2020).

Metformin as adjunctive therapy for dengue in overweight and obese patients: a protocol for an open-label clinical trial (MeDO)

Background:  Dengue is a disease of major global importance. While most symptomatic infections are mild, a small proportion of patients progress to severe disease with risk of hypovolaemic shock, organ dysfunction and death.  In the absence of effective antiviral or disease modifying drugs, clinical management is solely reliant on supportive measures. Obesity is a growing problem among young people in Vietnam and is increasingly recognised as an important risk factor for severe dengue, likely due to alterations in host immune and inflammatory pathways. Metformin, a widely used anti-hyperglycaemic agent with excellent safety profile, has demonstrated potential as a dengue therapeutic in vitro and in a retrospective observational study of adult dengue patients with type 2 diabetes.  This study aims to assess the safety and tolerability of metformin treatment in overweight and obese dengue patients, and investigate its effects on several clinical, immunological and virological markers of disease severity.

Methods: This open label trial of 120 obese/overweight dengue patients will be performed in two phases, with a metformin dose escalation if no safety concerns arise in phase one. The primary endpoint is identification of clinical and laboratory adverse events.  Sixty overweight and obese dengue patients aged 10-30 years will be enrolled at the Hospital for Tropical Diseases in Ho Chi Minh City, Vietnam. Participants will complete a 5-day course of metformin therapy and be compared to a non-treated group of 60 age-matched overweight and obese dengue patients.

Discussion:  Previously observed antiviral and immunomodulatory effects of metformin make it a promising dengue therapeutic candidate in appropriately selected patients. This study will assess the safety and tolerability of adjunctive metformin in the management of overweight and obese young dengue patients, as well as its effects on markers of viral replication, endothelial dysfunction and host immune responses. 

Trial registration: ClinicalTrials.gov: NCT04377451 (May 6 ^th 2020).

Effect of Metformin on Circulating Levels of Inflammatory Markers in Patients With Type 2 Diabetes: A Systematic Review and Meta-analysis of Randomized Controlled Trials

BACKGROUND

Emerging evidence indicates that metformin has anti-inflammatory effect; however, the results differ concerning randomized controlled trails of the effect of metformin on inflammatory markers in type 2 diabetes (T2D) patients.

OBJECTIVE

This study reassessed the data on the effect of metformin treatment on inflammatory markers in T2D patients through a systematic review and meta-analysis.

METHODS

A systematic search was performed in the PubMed, ISI Web of Science, EMBASE, Cochrane Library and Scopus databases to collect relevant published data up to September 2020. Data of each study was combined using random-effects model. Subgroup analysis was performed based on subgroups of the treatment duration, dose and target population.

RESULTS

Thirteen RCTs including 1776 participants with T2D were analyzed. Although CRP levels significantly decreased [SMD: -0.76 mg/L; 95% CI (-1.48, -0.049); P = 0.036] in patients with T2D following metformin treatment, circulating levels of TNF-α [SMD: -0.17 pg/mL; 95% CI (-0.55, 0.20); P = 0.37] and IL-6 [SMD: -0.06 pg/mL; 95% CI (-0.38, 0.25); P = 0.69] were insignificant after metformin treatment. Compared to treatment duration of less than 24 weeks, longer treatment duration (more than 24 weeks) was associated with reduced level of CRP.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

Based on available evidence from RCTs in this meta-analysis, metformin decreased CRP level. However, strategies for the treatment of inflammation should focus on metformin in patients with T2D.

CONCLUSION

The present study evidences that therapy with metformin can reduce CRP level significantly in T2D patients compared to other inflammatory markers.

Adipokines as a therapeutic target by metformin to improve metabolic function: A systematic review of randomized controlled trials

Metformin is a widely used glucose-lowering drug, although its impact on adipose tissue function remains elusive. Adipose tissue-derived molecules regulate diverse physiological mechanisms, including energy metabolism, insulin sensitization, and inflammatory response. Alternatively, it has remained relevant to understand the therapeutic regulation of adipokines in efforts to alleviate inflammation in conditions associated with the metabolic syndrome. The current qualitative analysis of available literature focused on randomized clinical trials (RCTs) assessing the association between administration of metformin and adipokine regulation in individuals with metabolic syndrome. The major electronic databases such as MEDLINE, Cochrane Library, Scopus, and EMBASE were searched for eligible RCTs. Overall, 13 RCTs met the inclusion criteria, with a total of 4605 participants. Patients with metabolic syndrome were characterized by a state of obesity, impaired glucose tolerance, insulin resistance, and type 2 diabetes. Cumulative evidence from these RCTs supported the blood glucose lowering effects of metformin, in addition to promoting weight loss, ameliorating insulin resistance, and reducing pro-inflammatory markers such as interleukin-6 and tumor necrosis factor-α in patients with metabolic syndrome. Importantly, these therapeutic effects are associated with the upregulation of adiponectin and suppression of leptin and resistin.

Metformin Therapy Reduces Obesity Indices in Children and Adolescents: A Systematic Review and Meta-Analysis of Randomized Clinical Trials

Purpose: Few studies have summarized findings for the effect of metformin on obesity indices. Therefore, we aimed to conduct a systematic review and meta-analysis on the effect of metformin on obesity indices among children and adolescents. Methods: Relevant articles published up to September 2018 were searched in SCOPUS, Medline, and Google Scholar using appropriate keywords. All clinical trials that examined the effect of metformin on obesity indices in children and adolescents were included. Results: Overall, 38 studies, including 2199 participants (39.75% male and 60.25% female), were included. The pooled results indicated that metformin significantly reduced BMI [weighted mean difference (WMD): -1.07 kg/m²; 95% confidence interval (CI): -1.43 to -0.72]. Same findings were found for waist circumference (WC) (WMD: -1.93 cm; 95% CI: -2.69 to -1.16). Metformin also reduced body weight in all participants (WMD: -2.51 kg; 95% CI: -3.14 to -1.89). Moreover, it reduced body fat mass in patients with overweight or obesity (WMD: -1.90%; 95% CI: -3.25 to -0.56) and chronic diseases (WMD: -1.41%; 95% CI: -2.23 to -0.58), but not among those with growth problems. Metformin therapy did not affect lean body mass (LBM) in patients with overweight or obesity and growth problems; however, it reduced LBM in patients with chronic diseases (WMD: -1.49 kg; 95% CI: -2.69 to -0.30). Conclusions: We found a significant reduction in BMI, body weight, WC, and fat mass following administration with metformin. However, the effect of metformin on LBM was not significant. Further studies are required to confirm these findings.

Effects of metformin administration on endocrine-metabolic parameters, visceral adiposity and cardiovascular risk factors in children with obesity and risk markers for metabolic syndrome: A pilot study

Background

Metformin treatment (1000–2000 mg/day) over 6 months in pubertal children and/or adolescents with obesity and hyperinsulinism is associated with a reduction in body mass index (BMI) and the insulin resistance index (HOMA-IR). We aimed to ascertain if long-term treatment (24 months) with lower doses of metformin (850 mg/day) normalizes the endocrine-metabolic abnormalities, improves body composition, and reduces the carotid intima-media thickness (cIMT) in pre-puberal and early pubertal children with obesity.

Methods

A pilot double-blind, placebo-controlled trial was conducted on 18 pre-puberal and early pubertal (Tanner stage I-II) children with obesity and risk markers for metabolic syndrome. Patients were randomly assigned (1:1) to receive metformin (850 mg/day) or placebo for 24 months. Clinical, biochemical (insulin, lipids, leptin, and high-sensitivity C-reactive protein [hsCRP]), and imaging (body composition [dual-energy X-ray absorptiometry and magnetic resonance imaging]) parameters as well as cIMT (ultrasonography) were assessed at baseline and at 6, 12, and 24 months.

Results

The 12-month treatment tend to cause a reduction in weight standard deviation scores (SDS), BMI-SDS, leptin, leptin–to–high-molecular-weight (HMW) adiponectin ratio, hsCRP, cIMT, fat mass, and liver fat in metformin-treated children compared with placebo. The effect of metformin on the reduction of BMI-SDS, leptin, leptin-to-HMW adiponectin ratio, hsCRP, and liver fat seemed to be maintained after completing the 24 months of treatment. No changes in insulin sensitivity (HOMA-IR) or adverse effects were detected.

Conclusion

In this pilot study, metformin treatment in pre-puberal and early pubertal children with obesity seemed to improve body composition and inflammation markers. Our data encourage the development of future fully powered trials using 850 mg/day metformin in young children, highlighting its excellent tolerance and potential long-term benefits.

Metformin for prevention or delay of type 2 diabetes mellitus and its associated complications in persons at increased risk for the development of type 2 diabetes mellitus

BACKGROUND

The projected rise in the incidence of type 2 diabetes mellitus (T2DM) could develop into a substantial health problem worldwide. Whether metformin can prevent or delay T2DM and its complications in people with increased risk of developing T2DM is unknown.

OBJECTIVES

To assess the effects of metformin for the prevention or delay of T2DM and its associated complications in persons at increased risk for the T2DM.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials, MEDLINE, Scopus, ClinicalTrials.gov, the World Health Organization (WHO) International Clinical Trials Registry Platform and the reference lists of systematic reviews, articles and health technology assessment reports. We asked investigators of the included trials for information about additional trials. The date of the last search of all databases was March 2019.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) with a duration of one year or more comparing metformin with any pharmacological glucose-lowering intervention, behaviour-changing intervention, placebo or standard care in people with impaired glucose tolerance, impaired fasting glucose, moderately elevated glycosylated haemoglobin A1c (HbA1c) or combinations of these.

DATA COLLECTION AND ANALYSIS

Two review authors read all abstracts and full-text articles and records, assessed risk of bias and extracted outcome data independently. We used a random-effects model to perform meta-analysis and calculated risk ratios (RRs) for dichotomous outcomes and mean differences (MDs) for continuous outcomes, using 95% confidence intervals (CIs) for effect estimates. We assessed the certainty of the evidence using GRADE.

MAIN RESULTS

We included 20 RCTs randomising 6774 participants. One trial contributed 48% of all participants. The duration of intervention in the trials varied from one to five years. We judged none of the trials to be at low risk of bias in all 'Risk of bias' domains. Our main outcome measures were all-cause mortality, incidence of T2DM, serious adverse events (SAEs), cardiovascular mortality, non-fatal myocardial infarction or stroke, health-related quality of life and socioeconomic effects.The following comparisons mostly reported only a fraction of our main outcome set. Fifteen RCTs compared metformin with diet and exercise with or without placebo: all-cause mortality was 7/1353 versus 7/1480 (RR 1.11, 95% CI 0.41 to 3.01; P = 0.83; 2833 participants, 5 trials; very low-quality evidence); incidence of T2DM was 324/1751 versus 529/1881 participants (RR 0.50, 95% CI 0.38 to 0.65; P < 0.001; 3632 participants, 12 trials; moderate-quality evidence); the reporting of SAEs was insufficient and diverse and meta-analysis could not be performed (reported numbers were 4/118 versus 2/191; 309 participants; 4 trials; very low-quality evidence); cardiovascular mortality was 1/1073 versus 4/1082 (2416 participants; 2 trials; very low-quality evidence). One trial reported no clear difference in health-related quality of life after 3.2 years of follow-up (very low-quality evidence). Two trials estimated the direct medical costs (DMC) per participant for metformin varying from $220 to $1177 versus $61 to $184 in the comparator group (2416 participants; 2 trials; low-quality evidence). Eight RCTs compared metformin with intensive diet and exercise: all-cause mortality was 7/1278 versus 4/1272 (RR 1.61, 95% CI 0.50 to 5.23; P = 0.43; 2550 participants, 4 trials; very low-quality evidence); incidence of T2DM was 304/1455 versus 251/1505 (RR 0.80, 95% CI 0.47 to 1.37; P = 0.42; 2960 participants, 7 trials; moderate-quality evidence); the reporting of SAEs was sparse and meta-analysis could not be performed (one trial reported 1/44 in the metformin group versus 0/36 in the intensive exercise and diet group with SAEs). One trial reported that 1/1073 participants in the metformin group compared with 2/1079 participants in the comparator group died from cardiovascular causes. One trial reported that no participant died due to cardiovascular causes (very low-quality evidence). Two trials estimated the DMC per participant for metformin varying from $220 to $1177 versus $225 to $3628 in the comparator group (2400 participants; 2 trials; very low-quality evidence). Three RCTs compared metformin with acarbose: all-cause mortality was 1/44 versus 0/45 (89 participants; 1 trial; very low-quality evidence); incidence of T2DM was 12/147 versus 7/148 (RR 1.72, 95% CI 0.72 to 4.14; P = 0.22; 295 participants; 3 trials; low-quality evidence); SAEs were 1/51 versus 2/50 (101 participants; 1 trial; very low-quality evidence). Three RCTs compared metformin with thiazolidinediones: incidence of T2DM was 9/161 versus 9/159 (RR 0.99, 95% CI 0.41 to 2.40; P = 0.98; 320 participants; 3 trials; low-quality evidence). SAEs were 3/45 versus 0/41 (86 participants; 1 trial; very low-quality evidence). Three RCTs compared metformin plus intensive diet and exercise with identical intensive diet and exercise: all-cause mortality was 1/121 versus 1/120 participants (450 participants; 2 trials; very low-quality evidence); incidence of T2DM was 48/166 versus 53/166 (RR 0.55, 95% CI 0.10 to 2.92; P = 0.49; 332 participants; 2 trials; very low-quality evidence). One trial estimated the DMC of metformin plus intensive diet and exercise to be $270 per participant compared with $225 in the comparator group (94 participants; 1 trial; very-low quality evidence). One trial in 45 participants compared metformin with a sulphonylurea. The trial reported no patient-important outcomes. For all comparisons there were no data on non-fatal myocardial infarction, non-fatal stroke or microvascular complications. We identified 11 ongoing trials which potentially could provide data of interest for this review. These trials will add a total of 17,853 participants in future updates of this review.

AUTHORS' CONCLUSIONS

Metformin compared with placebo or diet and exercise reduced or delayed the risk of T2DM in people at increased risk for the development of T2DM (moderate-quality evidence). However, metformin compared to intensive diet and exercise did not reduce or delay the risk of T2DM (moderate-quality evidence). Likewise, the combination of metformin and intensive diet and exercise compared to intensive diet and exercise only neither showed an advantage or disadvantage regarding the development of T2DM (very low-quality evidence). Data on patient-important outcomes such as mortality, macrovascular and microvascular diabetic complications and health-related quality of life were sparse or missing.

Childhood obesity: increased risk for cardiometabolic disease and cancer in adulthood

Prevalence of childhood obesity has worldwide more than doubled since 1980. Underlying factors are complex and are far from completely understood. Strategies to prevent childhood obesity have mainly focused on behavioral intervention; and obesity therapy was mainly based on lifestyle modification to date. However, effects for both have been quite limited so far and no country has succeeded in fighting the obesity epidemy we are facing. Normalization of body weight before onset of puberty is crucial for several reasons: First, obese children and adolescents frequently stay obese until adulthood. Second, obesity during adolescence is significantly associated with increased risk for cardiovascular and metabolic disease such as type 2 diabetes in adulthood. And third, recent data have shown a strong association between higher body mass index (BMI) during adolescence and increased risk for several malignancies such as leukemia, Hodgkin's disease, colorectal cancer, breast cancer and others in adulthood. This review summarizes our current understanding of epidemiology, underlying factors, concomitant disease, as well as available intervention strategies and gives an overview of what has been reached so far and what measures should be undertaken to counteract the obesogenic environment.

The effects of metformin on insulin resistance in overweight or obese children and adolescents: A PRISMA-compliant systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Metformin has shown its effectiveness in reducing body mass index (BMI) in obese children and adolescents, but relevant evidence for improving insulin resistance in overweight or obese children and adolescents is inconclusive.

OBJECTIVES

This study aimed to assess whether metformin could effectively and safely improve homeostasis model assessment insulin resistance index (HOMA-IR) and other related laboratory indicators including fasting glucose, fasting insulin, high-density lipoprotein cholesterol (HDL-C), and low density lipoprotein-cholesterol (LDL-C).

METHODS

Searches were carried out in PubMed, CENTRAL, Web of Science, EMBASE, CBM, Chinese National Knowledge Infrastructure (CNKI), and WanFang from their inception until March 2018. Randomized controlled trials (RCTs) comparing metformin alone with placebo in overweight or obese children and adolescents were included. The Cochrane risk of bias tool was applied to assess the methodological quality of every study and Meta-analysis was carried out with a random effects model or a fixed effects model. Publication bias was evaluated by the Begg and Egger tests.

RESULTS

A total of 11 trials with a total of 865 participants met the inclusion criteria. Participants were between 4 and 18 years old. The time span of these studies ranged from 2001 to 2017. The daily dose of metformin was from 1000 mg to 2000 mg and the duration of intervention was 8 weeks to 18 months. Compared with placebo, metformin with lifestyle intervention reduced the level of LDL-C (P = 008, MD = - 4.29, 95% confidence interval [CI]: -7.45, -1.12). However, there was no obvious differences in improving insulin resistance, fasting glucose, and HDL-C.

CONCLUSION

Metformin may improve the level of LDL-C, but it has no significant effect on insulin resistance. The use of metformin may be a new approach to lipid metabolism management in overweight or obese children and adolescents.

REGISTRATION NUMBER

CRD42018092059.

New Insights about How to Make an Intervention in Children and Adolescents with Metabolic Syndrome: Diet, Exercise vs. Changes in Body Composition. A Systematic Review of RCT

OBJECTIVE

To record which interventions produce the greatest variations in body composition in patients ≤19 years old with metabolic syndrome (MS).

METHOD

search dates between 2005 and 2017 in peer reviewed journals, following the PRISMA method (Preferred Reporting Items for Systematic reviews and Meta-Analyses). The selection criteria were: diagnostic for MS or at least a criterion for diagnosis; randomized clinical trials, ≤19 years of age; intervention programs that use diet and/or exercise as a tool (interventions showing an interest in body composition).

RESULTS

1781 clinical trials were identified under these criteria but only 0.51% were included. The most frequent characteristics of the selected clinical trials were that they used multidisciplinary interventions and were carried out in America. The most utilized parameters were BMI (body mass index) in kg/m² and BW (body weight) in kg.

CONCLUSIONS

Most of the clinical trials included had been diagnosed through at least 2 diagnostic criteria for MS. Multidisciplinary interventions obtained greater changes in body composition in patients with MS. This change was especially prevalent in the combinations of dietary interventions and physical exercise. It is proposed to follow the guidelines proposed for patients who are overweight, obese, or have diabetes type 2, and extrapolate these strategies as recommendations for future clinical trials designed for patients with MS.

Effect of metformin combined with lifestyle modification versus lifestyle modification alone on proinflammatory-oxidative status in drug-naïve pre-diabetic and diabetic patients: A randomized controlled study

BACKGROUND

Targeting biomarkers of oxidative-proinflammatory stress may result in improvement of modifiable metabolic syndrome, pre-diabetes and diabetes risk factors and subsequent risk reduction.

METHODS

64 newly diagnosed antihyperglycemic treatment-naïve prediabetic and type 2 diabetes mellitus (T2DM) patients were randomly assigned using block design to either metformin combined with therapeutic lifestyle changes (TLC) or TLC alone. Body mass index (BMI), waist circumference, blood pressure, fasting plasma glucose (FPG), glycated hemoglobin (HbA1c), fasting lipid profile, plasma oxidative status and tumor necrosis factor (TNF)-α were measured at baseline, after 3 months and after 6 months from baseline.

RESULTS

Except for HbA1c, baseline values did not differ significantly between the two groups. The post 3-months relative reductions in BMI (P=0.014) and HbA1c (P=0.037) in metformin combined with TLC intervention were significantly greater than those in TLC alone group. TNFα plasma levels were decreased significantly vs. baseline by metformin combined with TLC intervention (-22.90±46.76%, P=0.01). Conversely, TLC alone basically worsened proinflammatory status (42.40±40.82 %), P<0.001. Metformin with TLC treatment effected a therapeutic decrement of the oxidative stress (-15.44±35.32%, P=0.029 vs. baseline) unlike TLC alone (61.49±122.66%, P=0.01 vs. baseline). Both interventions' effects were sustained in the 6-month follow up periods.

CONCLUSION

In both intervention groups, the relative changes in plasma TNFα were significantly correlated (P<0.01) with systolic blood pressure and the relative changes in oxidative stress were markedly correlated (P<0.05) with total cholesterol.

Metformin Use in Children and Adolescents with Prediabetes

With the increasing incidence of childhood obesity, clinicians need to understand its comorbidities and their management. The American Diabetes Association recommends pediatricians screen high-risk overweight and obese children. Identifying and treating prediabetic children and adolescents can help to reduce the burden of type 2 diabetes. Lifestyle interventions are pivotal. Metformin is the only oral medication approved for diabetes treatment in children. It has been studied in clinical trials in nondiabetic children and has been shown to have beneficial effects on body weight. Effects on diabetes prevention have not been studied and long-term data are limited in the pediatric population.

Metformin for Obesity in Prepubertal and Pubertal Children: A Randomized Controlled Trial

OBJECTIVES

Metformin has shown its effectiveness in treating obesity in adults. However, little research has been conducted in children, with a lack of attention on pubertal status. The objectives were to determine whether oral metformin treatment reduces BMI z score, cardiovascular risk, and inflammation biomarkers in children who are obese depending on pubertal stage and sex.

METHODS

This was a randomized, prospective, double-blind, placebo-controlled, multicenter trial, stratified according to pubertal stage and sex, conducted at 4 Spanish clinical hospitals. Eighty prepubertal and 80 pubertal nondiabetic children who were obese aged 7 to 14 years with a BMI >95th percentiles were recruited. The intervention included 1 g/d of metformin versus placebo for 6 months. The primary outcome was a reduction in BMI z score. Secondary outcomes comprised insulin resistance, cardiovascular risk, and inflammation biomarkers.

RESULTS

A total of 140 children completed the study (72 boys). Metformin decreased the BMI z score versus placebo in the prepubertal group (-0.8 and -0.6, respectively; difference, 0.2; P = .04). Significant increments were observed in prepubertal children treated with metformin versus placebo recipients in the quantitative insulin sensitivity check index (0.010 and -0.007; difference, 0.017; P = .01) and the adiponectin-leptin ratio (0.96 and 0.15; difference, 0.81; P = .01) and declines in interferon-γ (-5.6 and 0; difference, 5.6; P = .02) and total plasminogen activator inhibitor-1 (-1.7 and 2.4; difference, 4.1; P = .04). No serious adverse effects were reported.

CONCLUSIONS

“Metformin decreased the BMI z score and improved inflammatory and cardiovascular-related obesity parameters only in prepubertal children, but a differential effect of metformin was not observed in prepubertal compared to pubertal children. Nevertheless, the doses per kilogram of weight administrated may have had an impact on the metformin effect. Further investigations are necessary.”

The rs10401670 variant in resistin gene improved insulin resistance response and metabolic parameters secondaries to weight loss after a hypocaloric diet

BACKGROUND

The SNP 3'UTR C/T (rs10401670), it is a polymorphism that has been associated with diabetes mellitus and it has been scarcely studied before. As far as we know, no studies on interaction among diet intervention, rs10401670 variant of RETN and metabolic response has been realized.

OBJECTIVE

Our aim was to analyze the effects of the rs10401670 RETN gene polymorphism on insulin resistance response and metabolic changes secondary to weight loss after 3 months of a hypocaloric diet in adults obese patients without diabetes mellitus.

DESIGN

A Caucasian population of 135 obese patients without diabetes mellitus was analyzed. Before and after 3 months on a low fat hypocaloric diet, an anthropometric evaluation, an assessment of nutritional intake and a biochemical analysis were performed. The statistical analysis was performed for the combined CT and TT as a group (minor allele group) and wild type CC as second group (major allele group) (dominant model).

RESULTS

Forty nine patients (36.3%) had the genotype CC (major allele group) and 86 (63.7%) patients had the next genotypes; CT (67 patients, 49.6%) or TT (19 patients, 14.1%) (minor allele group). After dietary treatment and in major allele group, weight, BMI, fat mass, systolic blood pressure and waist circumference decreases were similar than minor allele group. In T allele carriers, fasting plasma glucose, insulin, HOMA-IR, total cholesterol and LDL cholesterol levels decreased significantly. In non T allele carriers and after dietary treatment, only LDL cholesterol and total cholesterol decreased. In non T Allele carriers, the decrease in total cholesterol was -15.1 ± 18.3 mg/dl (decrease in T Allele carriers -18.3 ± 15.7 mg/dl: p > 0.05), LDL-cholesterol was -14.3 ± 18.5 mg/dl (decrease in T Allele carriers -17.3 ± 10.1 mg/dl:p > 0.05), fasting glucose plasma -2.2 ± 1.5 mg/dL (decrease in T Allele carriers -4.8 ± 1.2 mg/dL: p = 0.02), insulin -1.1 ± 2.0 mUI/L (decrease in T Allele carriers -6.3 ± 1.9 mUI/L: p = 0.001) and HOMA-IR -0.2 ± 1.0 (decrease in T Allele carriers -1.8 ± 1.4: p = 0.005). Leptin levels decrease in both genotypes after dietary treatment (-21.1 ± 8.5 ng/dL in nonT Allele carriers vs -16.2 ± 10.2 ng/dL in T Allele carriers:p > 0.05). Resistin remained unchanged in both groups.

CONCLUSION

In our study in non-diabetic obese subjects, we describe an association of rs10401670T allele with a better metabolic response (glucose, insulin and HOMA-IR) secondary to weight loss with a hypocaloric diet.

The rs1862513 Variant in Resistin Gene-Modified Insulin Resistance and Insulin Levels after Weight Loss Secondary to Hypocaloric Diet

BACKGROUND/AIMS

Polymorphisms of a single nucleotide in RETN have been associated with indexes of insulin resistance. Our aim was to analyze the effects of the rs1862513 RETN gene polymorphism on insulin resistance, insulin levels, and resistin levels changes after 3 months of a low-fat hypocaloric diet.

DESIGN

A Caucasian population of 133 obese patients was analyzed before and after 3 months on a low-fat hypocaloric diet.

RESULTS

Fifty-six patients (42.1%) had the genotype GG (wild group) and 77 (57.9%) patients had the other genotypes; GC (59 patients, 44.4%) or CC (18 patients, 13.5%; mutant group). In wild and mutant genotype groups, weight, body mass index, fat mass, waist circumference, and systolic blood pressure decreased. In the wild genotype group, the decrease in total cholesterol was -13.1 ± 25.3 mg/dL (vs. -4.4 ± 13.7 mg/dL in mutant group: p = 0.004 for group deltas), low density lipoprotein (LDL)-cholesterol was -13.0 ± 21.5 mg/dL (-4.3 ± 10.5 mg/dL: p = 0.007), glucose -7.2 ± 3.5 mg/dL (-0.8 ± 0.2 mg/dL: p = 0.01), insulin -5.6 ± 2.5 mUI/L (-2.9 ± 1.2 mUI/L: p = 0.03) and homeostasis model assessment-insulin resistance (HOMA-IR) -2.5 ± 1.1 (-0.6 ± 1.4: p = 0.02). Leptin levels decreased in both genotypes (-10.1 ± 9.5 ng/dL in wild type group vs. -13.1 ± 0.2 ng/dL in mutant type group: p > 0.05).

CONCLUSION

The present study suggests that the G/G genotype of RETN rs1862513 could be a predictor of the reduction of HOMA-IR, insulin, fasting glucose and LDL cholesterol secondary to a hypocaloric diet in obese subjects.

Adiponectin, Insulin Sensitivity, β-Cell Function, and Racial/Ethnic Disparity in Treatment Failure Rates in TODAY

OBJECTIVE

The Treatment Options for type 2 Diabetes in Adolescents and Youth (TODAY) study demonstrated that glycemic failure rates in the three treatments combined-metformin plus rosiglitazone, metformin alone, and metformin plus lifestyle-were higher in non-Hispanic blacks (NHB; 52.8%) versus non-Hispanic whites (NHW; 36.6%) and Hispanics (H; 45.0%). Moreover, metformin alone was less effective in NHB versus NHW versus H youth. This study describes treatment-associated changes in adiponectin, insulin sensitivity, and β-cell function over time among the three racial/ethnic groups to understand potential mechanism(s) responsible for this racial/ethnic disparity.

RESEARCH DESIGN AND METHODS

TODAY participants underwent periodic oral glucose tolerance tests to determine insulin sensitivity, C-peptide index, and oral disposition index (oDI), with measurements of total and high-molecular-weight adiponectin (HMWA).

RESULTS

At baseline NHB had significantly lower HMWA than NHW and H and exhibited a significantly smaller increase (17.3% vs. 33.7% vs. 29.9%, respectively) during the first 6 months overall. Increases in HMWA were associated with reductions in glycemic failure in the three racial/ethnic groups combined (hazard ratio 0.61, P < 0.0001) and in each race/ethnicity separately. Over time, HMWA was significantly lower in those who failed versus did not fail treatment, irrespective of race/ethnicity. There were no differences in treatment-associated temporal changes in insulin sensitivity, C-peptide index, and oDI among the three racial/ethnic groups.

CONCLUSIONS

HMWA is a reliable biomarker of treatment response in youth with type 2 diabetes. The diminutive treatment-associated increase in HMWA in NHB (∼50% lower) compared with NHW and H may explain the observed racial/ethnic disparity with higher therapeutic failure rates in NHB in TODAY.

Resistin impairs glucose permeability in EA.hy926 cells by down-regulating GLUT1 expression

Type 2 diabetes mellitus (T2DM) is a chronic disease which is now affecting the health of more and more people in the world. Resistin, discovered in 2001, is considered to be closely related to metabolic dysfunction and obesity. Previous study showed that hyperglycemia is always accompanied by a high serum resistin concentration. We therefore investigated whether resistin can mediate glucose transfer across the blood-tissue barrier. Here, we employed a transwell system to analyze glucose permeability in EA.hy926 human endothelial cells treated without or with human resistin. In EA.hy926 cells treated with resistin, the permeability to glucose was heavily impaired. This was due to the down-regulation of GLUT1 expression as a result of the treatment, rather than regulation of tight junctions. In addition, overexpression of GLUT1 in EA.hy926 cells was able to recover the blocking effect of resistin on glucose permeability. We further found that resistin could inhibit the expression of peroxisome proliferator-activated receptor gamma (PPARγ) and consequently impede the transcription of GLUT1. The results of the present study suggested that resistin could cause glucose retention in serum and thus result in hyperglycemia. This provides a novel explanation for hyperglycemia and a potential new way of treating type 2 diabetes mellitus.

Effect of folic acid and metformin on insulin resistance and inflammatory factors of obese children and adolescents

Background:

Considering the increasing trend of obesity, especially in developing countries such as Iran, and the role of inflammatory factors and insulin resistance (IR) in the occurrence of obesity-related complications as well as the safety of some agents such as folic acid and metformin, this clinical trial was designed to investigate the effect of metformin and folic acid on inflammatory factors and IR among obese children.

Materials and Methods:

In this randomized, double-blind, controlled clinical trial study, sixty obese children aged 6–12 years were enrolled. Selected obese children were randomly allocated in two interventional (1 mg/daily folic acid or 1000 mg metformin for 8 weeks) groups. Biochemical measurements including homeostasis model assessment of IR (HOMA-IR), homocysteine (Hcy), tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and interleukin-8 (IL-8) were measured between and within the groups before and after trial.

Results:

In each group, thirty obese children were studied. The groups were age- and sex-matched. After folic acid and metformin administration, mean of Hcy, HOMA-IR, TNF-α, and IL-8 decreased significantly (P < 0.05). IL-6 decreased significantly after folic acid use (P < 0.05).

Conclusion:

The findings of this trial indicated that both metformin and folic acid could decrease IR and level of Hcy in obese children and adolescents. The effectiveness of metformin on IR was more significant than folic acid. Regarding the effectiveness of the two studied agents on inflammatory factors, it is suggested that the role of folic acid was superior to metformin. It is suggested that metformin is a proper agent for obese children with IR and folic acid is an appropriate supplement for obese children with increased inflammatory factors.

Adipokines in nonalcoholic fatty liver disease

Since the discovery of adipose tissue as a higly active endocrine tissue, adipokines, peptides produced by adipose tissue and exerting autocrine, paracrine and endocrine function, have gained increasing interest in various obesity-related diseases, including nonalcoholic fatty liver disease (NAFLD). Data regarding the association between NAFLD and circulating leptin and adiponectin levels are generally well documented: leptin levels increase, whereas adiponectin levels decrease, by increasing the severity of NAFLD. Data regarding other adipokines in histologically confirmed NAFLD populations are inconclusive (e.g., resistin, visfatin, retinol-binding protein-4, chemerin) or limited (e.g., adipsin, obestatin, omentin, vaspin etc.). This review summarizes evidence on the association between adipokines and NAFLD. The first part of the review provides general consideration on the interplay between adipokines and NAFLD, and the second part provides evidence on specific adipokines possibly involved in NAFLD pathogenesis. A thorough insight into the pathophysiologic mechanisms linking adipokines with NAFLD may result in the design of studies investigating the combined adipokine use as noninvasive diagnostic markers of NAFLD and new clinical trials targeting the treatment of NAFLD.

Evaluation of differential effects of metformin treatment in obese children according to pubertal stage and genetic variations: study protocol for a randomized controlled trial

BACKGROUND

Overweight and obesity are considered to be serious public health problems. In pediatric populations, insulin resistance, dyslipidemia, and hypertension associated with obesity occur with increased frequencies. Metformin is an oral anti-hyperglycemic agent that has been demonstrated to be efficacious in the treatment of diabetic and non-diabetic obese adults. A considerable amount of pharmacogenetic research has demonstrated that genetic variation is one of the major factors affecting metformin response. Additionally, potential microbiota-mediated mechanisms of metformin effect have been recently described. However, scant work has been conducted in children, with no attention being paid to the potential effects of pubertal development. Thus, the main objective of the present study is to evaluate the effect of metformin treatment together with lifestyle recommendations in a randomized control trial (RCT) of obese children according to pubertal stage, genetic variants and signature of gut microbiota.

METHODS/DESIGN

This is a randomized, prospective, double-blind, placebo-controlled, multicenter trial, which is stratified by puberty and sex. Eighty pre-pubertal (40 boys and 40 girls) and 80 pubertal non-diabetic obese children (40 boys and 40 girls) are being recruited in four Spanish Clinical Hospitals. The inclusion criteria to participate in the RCT include a Body Mass Index (BMI) above the 95th percentile and age 7-14 years. The pubertal stage is determined based on the Tanner criteria. Participants are assigned to two groups in accordance with a randomization schedule and receive 1 g of metformin or placebo for six months in combination with healthy lifestyle recommendations in both groups. The primary outcomes include changes in the BMI Z score and the biomarkers associated with the early appearance of insulin resistance syndrome, inflammation, cardiovascular risk according of the presence of genetic determinants of metformin response, as well as possible modifications in microbiota.

DISCUSSION

This study will assess the differential response of metformin treatment at six months in pre-pubertal and pubertal obese children.

TRIAL REGISTRATION

Registered by European Clinical Trials Database (EudraCT, ID: 2010-023061-21) on 14 November 2011.

Metabolic Syndrome, Type 2 Diabetes, and Cancer: Epidemiology and Potential Mechanisms

Obesity is associated with multiple metabolic disorders that drive cardiovascular disease, T2D and cancer. The doubling in the number of obese adults over the past 3 decades led to the recognition of obesity as a "disease". With over 42 million children obese or overweight, this epidemic is rapidly growing worldwide. Obesity and T2D are both associated together and independently with an increased risk for cancer and a worse prognosis. Accumulating evidence from epidemiological studies revealed potential factors that may explain the association between obesity-linked metabolic disorders and cancer risk. Studies based on the insulin resistance MKR mice, highlighted the roe of the insulin receptor and its downstream signaling proteins in mediating hyperinsulinemia's mitogenic effects. Hypercholesterolemia was also shown to promote the formation of larger tumors and enhancement in metastasis. Furthermore, the conversion of cholesterol into 27-Hydroxycholesterol was found to link high fat diet-induced hypercholesterolemia with cancer pathophysiology. Alteration in circulating adipokines and cytokines are commonly found in obesity and T2D. Adipokines are involved in tumor growth through multiple mechanisms including mTOR, VEGF and cyclins. In addition, adipose tissues are known to recruit and alter macrophage phenotype; these macrophages can promote cancer progression by secreting inflammatory cytokines such as TNF-α and IL-6. Better characterization on the above factors and their downstream effects is required in order to translate the current knowledge into the clinic, but more importantly is to understand which are the key factors that drive cancer in each patient. Until we reach this point, policies and activities toward healthy diets and physical activities remain the best medicine.

Therapeutic Use of Metformin in Prediabetes and Diabetes Prevention

People with elevated, non-diabetic, levels of blood glucose are at risk of progressing to clinical type 2 diabetes and are commonly termed 'prediabetic'. The term prediabetes usually refers to high-normal fasting plasma glucose (impaired fasting glucose) and/or plasma glucose 2 h following a 75 g oral glucose tolerance test (impaired glucose tolerance). Current US guidelines consider high-normal HbA1c to also represent a prediabetic state. Individuals with prediabetic levels of dysglycaemia are already at elevated risk of damage to the microvasculature and macrovasculature, resembling the long-term complications of diabetes. Halting or reversing the progressive decline in insulin sensitivity and β-cell function holds the key to achieving prevention of type 2 diabetes in at-risk subjects. Lifestyle interventions aimed at inducing weight loss, pharmacologic treatments (metformin, thiazolidinediones, acarbose, basal insulin and drugs for weight loss) and bariatric surgery have all been shown to reduce the risk of progression to type 2 diabetes in prediabetic subjects. However, lifestyle interventions are difficult for patients to maintain and the weight loss achieved tends to be regained over time. Metformin enhances the action of insulin in liver and skeletal muscle, and its efficacy for delaying or preventing the onset of diabetes has been proven in large, well-designed, randomised trials, such as the Diabetes Prevention Program and other studies. Decades of clinical use have demonstrated that metformin is generally well-tolerated and safe. We have reviewed in detail the evidence base supporting the therapeutic use of metformin for diabetes prevention.

Adolescent oligomenorrhea (age 14-19) tracks into the third decade of life (age 20-28) and predicts increased cardiovascular risk factors and metabolic syndrome

OBJECTIVE

Assess whether adolescent oligomenorrhea (age 14-19) tracks into young adulthood (age 20-28) and predicts increased cardiometabolic risk factors, metabolic syndrome (MetS), and impaired fasting glucose-type II diabetes mellitus (IFG+T2DM).

MATERIALS AND METHODS

Prospective study of menstrual cyclicity and its metabolic effects in 865 black and white schoolgirls from age 9 to 19, and 605 of these 865 girls from age 20 to 28.

MAIN FINDINGS

Patterns of menstrual delays (oligomenorrhea) during ages 14-19 and ages 20-28 were closely related (p<.0001). Adolescent menses delay (ages 14-19, p<.0001), mean insulin (ages 20-28, p=.0003), and self-identified polycystic ovary syndrome (PCOS, p=.049) predicted ages 20-28 menses delay. Menses delays during ages 14-19 and 20-28, and, their interaction product were correlated with IFG+T2DM and MetS at ages 20-28. Waist circumference (ages 20-28, p<.0001), mean triglyceride (ages 20-28, p=.005), and the number of average menstrual cycles≥42 days (ages 20-28, p=.04) predicted IFG+T2DM (ages 20-28). MetS (ages 9-19, p<.0001), mean insulin (ages 20-28, p=.0002), the number of ≥42 day gaps between menstrual periods (ages 20-28, p=.02), and cigarette smoking at age 18-19 (p=.04) were significant explanatory variables for MetS at ages 27-28. As MetS status category changed from age 14-19 to 27-28 from best to worst: (no → no), (yes → no), (yes → yes), (no → yes), the number of women with ≥2 menses delays during ages 20-28 rose from 3% to 4% to 15% to 17%, p=.0001. MetS status change from age 9-19 to 27-28 was positively associated with mean insulin (age 20-28, p<.0001), cigarette smoking (age 24-25, p=.01) and the number of menses delays during ages 20-28 (p=.04).

PRINCIPAL CONCLUSIONS

Menstrual patterns track from adolescence to young adulthood, and oligomenorrhea predicts MetS and IFG+T2DM. Patterns of menses delays in adolescence should be considered as a significant risk factor for future development of young adult IFG+T2DM, MetS, oligomenorrhea, and polycystic ovary syndrome.

The impact of metformin treatment on adiponectin and resistin levels in women with polycystic ovary syndrome: a prospective clinical study

Women with polycystic ovary syndrome (PCOS) are often characterized by adiposity and insulin resistance (IR). Recent studies in patients with obesity and diabetes mellitus type 2 (DMt2) indicate that adiponectin and resistin may play a role in the pathophysiology of IR. The aim of this study was to identify a possible correlation between the plasma levels of adiponectin and resistin and IR in patients with PCOS. Thirty-one women of reproductive age were enrolled in this prospective study after being diagnosed with PCOS and IR according to Rotterdam and American Diabetes Association (ADA) criteria, respectively. Every patient was treated with a daily dose of 1275 mg metformin for 6 months. Adiponectin, resistin, and the primary hormonal and metabolic parameters of the syndrome were evaluated at entry and endpoint of treatment. Adiponectin plasma levels were reduced after metformin treatment, but resistin levels were not significantly affected. Our study suggests that circulating levels of adiponectin should be evaluated with skepticism in patients with PCOS. The adipokine's role in the manifestation of IR in PCOS remains unclear and needs further investigation.

Metformin--mode of action and clinical implications for diabetes and cancer

Metformin has been the mainstay of therapy for diabetes mellitus for many years; however, the mechanistic aspects of metformin action remained ill-defined. Recent advances revealed that this drug, in addition to its glucose-lowering action, might be promising for specifically targeting metabolic differences between normal and abnormal metabolic signalling. The knowledge gained from dissecting the principal mechanisms by which metformin works can help us to develop novel treatments. The centre of metformin's mechanism of action is the alteration of the energy metabolism of the cell. Metformin exerts its prevailing, glucose-lowering effect by inhibiting hepatic gluconeogenesis and opposing the action of glucagon. The inhibition of mitochondrial complex I results in defective cAMP and protein kinase A signalling in response to glucagon. Stimulation of 5'-AMP-activated protein kinase, although dispensable for the glucose-lowering effect of metformin, confers insulin sensitivity, mainly by modulating lipid metabolism. Metformin might influence tumourigenesis, both indirectly, through the systemic reduction of insulin levels, and directly, via the induction of energetic stress; however, these effects require further investigation. Here, we discuss the updated understanding of the antigluconeogenic action of metformin in the liver and the implications of the discoveries of metformin targets for the treatment of diabetes mellitus and cancer.

Role of obesity on all-cause mortality in whites with type 2 diabetes from Italy

Mortality rate of diabetic patients is twice as much that of non-diabetic individuals. The role of obesity on mortality risk in patients with type 2 diabetes is controversial. Aim of our study was to address the relationship between obesity and all-cause mortality in a real-life set of white patients with type 2 diabetes from central-southern Italy from the Gargano Mortality Study (GMS). In addition, we used genetic data from genome-wide association studies (GWAs)-derived single nucleotide polymorphisms (SNPs) firmly associated with body mass index (BMI), in order to investigate the intrinsic nature of reduced mortality rate we, in fact, observed in obese patients. Study subjects with type 2 diabetes (n = 764) are part of the GMS, which is aimed at unraveling predictors of incident all-cause mortality. Time-to-death analyses were performed by Cox regression. Association between genotype risk score and obesity was tested by logistic regression. Of the 32 SNPs firmly associated with BMI, we investigated those with BMI β value ≥0.10 kg/m(2) and allele frequency ≥10 %. Genotyping was performed by KBioscience (http://www.lgcgenomics.com/). In GMS, obesity predicted a 45 % reduction in all-cause mortality. Individuals with high "obesity genetic load" (i.e., those carrying >9 risk alleles) were 60 % more likely to be obese as compared to individuals with low "obesity genetic load." Most importantly, mortality rate was not different in individuals with high and low "obesity genetic load," thus indicating no role of obesity genes on all-cause mortality and speaking against a cause-effect relationship underlying the association between obesity and reduced mortality rate.

Potential applications for biguanides in oncology

Metformin is widely prescribed for the treatment of type II diabetes. Recently, it has been proposed that this compound or related biguanides may have antineoplastic activity. Biguanides may exploit specific metabolic vulnerabilities of transformed cells by acting on them directly, or may act by indirect mechanisms that involve alterations of the host environment. Preclinical data suggest that drug exposure levels are a key determinant of proposed direct actions. With respect to indirect mechanisms, it will be important to determine whether recently demonstrated metformin-induced changes in levels of candidate systemic mediators such as insulin or inflammatory cytokines are of sufficient magnitude to achieve therapeutic benefit. Results of the first generation of clinical trials now in progress are eagerly anticipated. Ongoing investigations may justify a second generation of trials that explore pharmacokinetic optimization, rational drug combinations, synthetic lethality strategies, novel biguanides, and the use of predictive biomarkers.

Antidiabetic treatment restores adiponectin serum levels and APPL1 expression, but does not improve adiponectin-induced vasodilation and endothelial dysfunction in Zucker diabetic fatty rats

Background

Adiponectin is able to induce NO-dependent vasodilation in Zucker lean (ZL) rats, but this effect is clearly alleviated in their diabetic littermates, the Zucker diabetic fatty (ZDF) rats. ZDF rats also exhibit hypoadiponectinemia and a suppressed expression of APPL1, an adaptor protein of the adiponectin receptors, in mesenteric resistance arteries. Whether an antidiabetic treatment can restore the vasodilatory effect of adiponectin and improve endothelial function in diabetes mellitus type 2 is not known.

Methods

During our animal experiment from week 11 to 22 in each case seven ZDF rats received an antidiabetic treatment with either insulin (ZDF+I) or metformin (ZDF+M). Six normoglycemic ZL and six untreated ZDF rats served as controls. Blood glucose was measured at least weekly and serum adiponectin levels were quantified via ELISA in week 11 and 22. The direct vasodilatory response of their isolated mesenteric resistance arteries to adiponectin as well as the endothelium-dependent and -independent function was evaluated in a small vessel myograph. Additionally, the expression of different components of the adiponectin signaling pathway in the resistance arteries was quantified by real-time RT-PCR.

Results

In ZDF rats a sufficient blood glucose control could only be reached by treatment with insulin, but both treatments restored the serum levels of adiponectin and the expression of APPL1 in small resistance arteries. Nevertheless, both therapies were not able to improve the vasodilatory response to adiponectin as well as endothelial function in ZDF rats. Concurrently, a downregulation of the adiponectin receptors 1 and 2 as well as endothelial NO-synthase expression was detected in insulin-treated ZDF rats. Metformin-treated ZDF rats showed a reduced expression of adiponectin receptor 2.

Conclusions

An antidiabetic treatment with either insulin or metformin in ZDF rats inhibits the development of hypoadiponectinemia and downregulation of APPL1 in mesenteric resistance arteries, but is not able to improve adiponectin induced vasodilation and endothelial dysfunction. This is possibly due to alterations in the expression of adiponectin receptors and eNOS.

Effects of endurance exercise training, metformin, and their combination on adipose tissue leptin and IL-10 secretion in OLETF rats

Adipose tissue inflammation plays a role in cardiovascular (CV) and metabolic diseases associated with obesity, insulin resistance, and type 2 diabetes mellitus (T2DM). The interactive effects of exercise training and metformin, two first-line T2DM treatments, on adipose tissue inflammation are not known. Using the hyperphagic, obese, insulin-resistant Otsuka Long-Evans Tokushima Fatty (OLETF) rat model, we tested the hypothesis that treadmill training, metformin, or a combination of these reduces the secretion of proinflammatory cytokines from adipose tissue. Compared with Long-Evans Tokushima Otsuka (LETO) control rats (L-Sed), sedentary OLETF (O-Sed) animals secreted significantly greater amounts of leptin from retroperitoneal adipose tissue. Conversely, secretion of interleukin (IL)-10 by O-Sed adipose tissue was lower than that in L-Sed animals. Examination of leptin and IL-10 secretion from adipose tissue in OLETF groups treated with endurance exercise training (O-EndEx), metformin treatment (O-Met), and a combination of these (O-E+M) from 20 to 32 wk of age indicated that 1) leptin secretion from adipose tissue was reduced in O-Met and O-E+M, but not O-EndEx animals; 2) adipose tissue IL-10 secretion was increased in O-EndEx and O-E+M but not in O-Met animals; and 3) only the combined treatment (O-E+M) displayed both a reduction in leptin secretion and an increase in IL-10 secretion. Leptin and IL-10 concentrations in adipose tissue-conditioned buffers were correlated with their plasma concentrations, adipocyte diameters, and total adiposity. Overall, this study indicates that exercise training and metformin have additive influences on adipose tissue secretion and plasma concentrations of leptin and IL-10.

The effect of metformin on insulin resistance and exercise parameters in patients with heart failure

AIMS

Chronic heart failure (CHF) is an insulin-resistant state. The degree of insulin resistance (IR) correlates with disease severity and is associated with reduced exercise capacity. In this proof of concept study, we have examined the effect of metformin on IR and exercise capacity in non-diabetic CHF patients identified to have IR.

METHODS AND RESULTS

In a double-blind, placebo-controlled study, 62 non-diabetic IR CHF patients (mean age, 65.2 ± 8.0 years; male, 90%; left ventricular ejection fraction, 32.6 ± 8.3%; New York Heart Association class I/II/III/IV, 11/45/6/0) were randomized to receive either 4 months of metformin (n = 39, 2 g/day) or matching placebo (n = 23). IR was defined by a fasting insulin resistance index (FIRI) ≥2.7. Cardiopulmonary exercise testing and FIRI were assessed at baseline and after 4 months of intervention. Compared with placebo, metformin decreased FIRI (from 5.8 ± 3.8 to 4.0 ± 2.5, P < 0.001) and resulted in a weight loss of 1.9 kg (P < 0.001). The primary endpoint of the study, peak oxygen uptake (VO(2)), did not differ between treatment groups. However, metformin improved the secondary endpoint of the slope of the ratio of minute ventilation to carbon dioxide production (VE/VCO(2) slope), from 32.9 ± 15.9 to 28.1 ± 8.8 (P = 0.034). In the metformin-treated group, FIRI was significantly related to the reduction of the VE/VCO(2) slope (R = 0.41, P = 0.036).

CONCLUSION

Metformin treatment significantly improved IR but had no effect on peak VO(2), the primary endpoint of our study. However, metformin treatment did result in a significant improvement in VE/VCO(2) slope.

TRIAL REGISTRATION

NCT00473876.