Metformin in prevention and treatment of antipsychotic induced weight gain: a systematic review and meta-analysis

BACKGROUND: Most antipsychotics are associated with weight gain and other metabolic complications. Several randomized trials have shown metformin to be effective, but this still hasn’t been included in clinical guidelines on managing antipsychotic induced weight gain. METHODS: All double blind placebo controlled trials assessing the efficacy of metformin in the treatment of antipsychotic induced weight gain were included. Cochrane Central Register of Controlled Trials (CENTRAL) and MEDLINE were searched for the period January 2000-December 2015. Meta-analysis was carried out using the random effects model. RESULTS: Meta analysis of 12 published studies with a total of 743 patients found that in patients treated with antipsychotics, metformin treatment resulted in significantly better anthropometric and metabolic parameters than placebo. The mean change in weight was −3.27 kg (95 % CI −4.66 to −1.89) (Z = 4.64, p < 0.001). Metformin compared to placebo resulted in significant reduction in BMI [−1.13 kg/m(2) (95 % CI −1.61 to −0.66)] and insulin resistance index [−1.49 (95 % CI −2.40 to −0.59)] but not fasting blood sugar [−2.48 mg/dl (95 % CI −5.54 to 0.57]. CONCLUSION: This meta-analysis confirms that metformin is effective in treating antipsychotic induced weight gain in patients with schizophrenia or schizoaffective disorder. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12888-016-1049-5) contains supplementary material, which is available to authorized users.