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The Optimal Dosage and Duration of Metformin for Prevention and Treatment of Antipsychotic-Induced Weight Gain: An Updated Systematic Review and Meta-Analysis

Peng TR, Chen JA, Lee JA, Hsing CP, Lee MC, Chen SM

Schizophrenia bulletin, 2025

1,070 participants

Abstract

BACKGROUND: Weight gain and metabolic complications are substantial adverse effects associated with second-generation antipsychotics. However, comprehensive guidelines for managing antipsychotic-induced weight gain are lacking.

METHODS: This review included all double-blind, placebo-controlled studies investigating metformin's effectiveness in addressing antipsychotic-related weight gain. We systematically searched PubMed, Embase, the Cochrane Central Register of Controlled Trials, Google Scholar, and ClinicalTrials.gov for relevant studies from the inception to 2024. A random-effects model was used for the meta-analysis.

RESULTS: This meta-analysis, including 20 studies with 1070 patients, revealed that metformin significantly surpassed placebo in attenuating weight gain in patients receiving antipsychotics. The mean weight change with metformin was -3.32 kg [95% confidence interval (CI): -4.57 to -2.07]. Additionally, metformin use resulted in a marked decrease in body mass index [-1.24 kg/m2 (95% CI: -1.70 to -0.77)]. Metformin could maintain the effects from 12 to 24 weeks.

CONCLUSIONS: This updated meta-analysis investigated the durations and dosages of metformin use in patients with schizophrenia experiencing antipsychotic-induced weight gain. The findings highlight the need for additional large-scale research to validate our findings.

How strong is the evidence?

Evidence Hub reads this as a meta-analysis, done in people. Its evidence level is 1 of 5 (Highest · pooled evidence). Pooled evidence from several studies sits at the top of the evidence pyramid. Reported size: 1,070 participants or records.

How the five levels of evidence work. The level is assigned automatically from the abstract and can be wrong, so check the paper.

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