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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.

Reports of amputations associated with sodium-glucose cotransporter 2 (SGLT2) inhibitors have been inconsistent. We aimed to compare the risk of below-knee amputation with SGLT2 inhibitors versus dipeptidyl peptidase 4 (DPP-4) inhibitors among patients with type 2 diabetes. RESEARCH DESIGN AND METHODSThis multicenter observational study used administrative health care databases from seven Canadian provinces and the U.K. Incident SGLT2 inhibitor users were matched to DPP-4 inhibitor users using a prevalent new-user design and timeconditional propensity scores. Cox proportional hazards models were used to estimate site-specific adjusted hazard ratios (HR) and corresponding 95% CIs of incident below-knee amputation for SGLT2 inhibitor versus DPP-4 inhibitor users. Random effects meta-analyses were used to pool the site-specific results. RESULTSThe study cohort included 207,817 incident SGLT2 inhibitor users matched to 207,817 DPP-4 inhibitor users. During a mean exposed follow-up time of 11 months, the amputation rate was 1.3 per 1,000 person-years among SGLT2 inhibitor users and 1.5 per 1,000 person-years among DPP-4 inhibitor users. The adjusted HR of below-knee amputations associated with SGLT2 inhibitor use compared with DPP-4 inhibitor use was 0.88 (95% CI 0.71-1.09). Similar results were obtained in stratified analyses by specific SGLT2 inhibitor molecule. CONCLUSIONSIn this large multicenter observational study, there was no association between SGLT2 inhibitor use and incident below-knee amputations among patients with type 2 diabetes compared with DPP-4 inhibitor use. While these findings provide some reassurance, studies with a longer duration of follow-up are needed to assess potential long-term effects.Sodium-glucose cotransporter 2 (SGLT2) inhibitors are the newest antidiabetic agents for type 2 diabetes management (1). They inhibit the SGLTs on renal proximal tubules, leading to glucosuria. This effect not only lowers glycemia but also induces weight loss and blood pressure reduction (2). Indeed, randomized placebo-controlled trials have shown that SGLT2 inhibitors also decrease the risk of cardiovascular outcomes (3,4) and heart failure (3-5). Current guidelines from the American Diabetes Association