Efficacy of metformin on glycemic control and weight in drug-naive type 2 diabetes mellitus patients: A systematic review and meta-analysis of placebo-controlled randomized trials

Aim of the study. - Metformin is recommended as the first-line treatment of type 2 diabetes mellitus. Despite its common use, few studies have been conducted to precisely measure the efficacy of metformin versus placebo as a first-line treatment. This study aims to assess the precise effects of metformin monotherapy on glycemic control and weight in drug-naive patients with type 2 diabetes mellitus. Methods. - Medline(R) and Cochrane databases were searched until March 19, 2016 to perform a systematic review and meta-analysis of placebo-controlled randomized trials evaluating metformin monotherapy in drug-naive patients with type 2 diabetes mellitus. Assessed outcomes include glycemic control (fasting plasma glucose, glycosated hemoglobin) and weight. Results. - Overall, 16 studies (1140 patients) were selected. Compared to placebo, metformin monotherapy was associated with decreased glycosated hemoglobin by 0.95% at 3 months (95% CI: 0.50 to 1.39, I-2 = 87%) and 1.32% at 6 months (95% CI: 1.01 to 1.62, I-2 = 71%), and decreased fasting plasma glucose by 1.92 mmol/L at 1 month (95% CI: 0.11 to 3.74, I-2 = 88%), 1.79 mmol/L at 3 months (95% CI: 0.92 to 2.66, I-2 = 88%) and 2.14 mmol/L at 6 months (95% CI: 1.17 to 3.12, I-2 = 82%). No significant difference was demonstrated for the comparisons of weight due to relatively small number of studies retrieved from the literature resulting in insufficient statistical power. Conclusion. - This study provides the precise effects of metformin monotherapy regarding the decreases in fasting plasma glucose and glycosated hemoglobin that physician can expected in drug-naive patients with type 2 diabetes mellitus. No evidence was found for the effects on weight. (C) 2018 Societe francaise de pharmacologie et de therapeutique. Published by Elsevier MassonSAS. All rights reserved.