Efficacy and Safety of Metformin for Obesity: A Systematic Review

The efficacy and safety of metformin for obesity in children and adolescents remains unclear. To assess the efficacy and safety of metformin via systematic review. Data sources included PubMed, Embase, the Cochrane Library, Scopus, and ClincalTrials.gov (inception to November 2019). 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. Two researchers independently extracted data and assessed quality. The primary outcomes were mean changes from baseline in BMI, BMI score, homeostatic model assessment of insulin resistance, and gastrointestinal adverse effects. 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 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%). The available evidence is of varying quality, with high heterogeneity between trials, suggesting some uncertainty in the benefits of metformin in this population. 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.