Role of metformin in overweight and obese people without diabetes: a systematic review and network meta-analysis

PurposeOur aim was to assess the efficacy of metformin for weight loss in overweight and obese people through a systematic review and network meta-analysis and to identify the most suitable dosage and intervention period for using metformin in adolescents and adults.MethodsWe searched databases for studies published by April 2018. A total of 34 trials (44 analyses) involving 8461 participants and 16 intervention arms were eligible. The study was registered with PROSPERO International prospective register of systematic reviews (CRD42017081053).ResultsMetformin was found to significantly decrease body mass index percentile (BMI) and had a tendency to decrease BMI (kg/m(2)) and weight (kg). Significant efficacy was observed in many subgroups. The metaregression may have identified the causes of heterogeneity as metformin dosage, control type, and intervention period. Network meta-analysis revealed that in adolescents, intervention with 2000mg/day metformin ranked better than other interventions; however, 1000mg/day metformin for 3months may be most suitable for adolescents. For adults, metformin at doses of 3000and 1000mg/day ranked the highest, other than minimeal and lifestyle interventions; moreover, intervention with 3000mg/day for 6months and 1000mg/day for 0.5months may be suitable for adults.ConclusionWhen considering the efficacy of interventions for losing weight, metformin offers clear advantages for overweight and obese populations.