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

Purpose: Our 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.

Methods: We 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).

Results: Metformin was found to significantly decrease body mass index percentile (BMI) and had a tendency to decrease BMI (kg/m) 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 2000 mg/day metformin ranked better than other interventions; however, 1000 mg/day metformin for 3 months may be most suitable for adolescents. For adults, metformin at doses of 3000 and 1000 mg/day ranked the highest, other than minimeal and lifestyle interventions; moreover, intervention with 3000 mg/day for 6 months and 1000 mg/day for 0.5 months may be suitable for adults.

Conclusion: When considering the efficacy of interventions for losing weight, metformin offers clear advantages for overweight and obese populations.