Does Metformin Help With Weight Loss in Antipsychotic Induced Weight Gain?

Patients with schizophrenia receiving metformin experience reductions in weight, body mass index (BMI), fasting glucose level, and insulin resistance index, according to new research in Schizophrenia Bulletin.

The current study sought to clarify appropriate dosing and treatment duration information for the use of metformin in preventing and managing antipsychotic-induced weight gain.

Researchers used PubMed, Google Scholar, Cochrane Central Register of Controlled Trials, Clinicaltrials.gov, and Embase databases to conduct their literature search. Studies could be published from the inception of each database up to June 18, 2024. Eligible studies had to be double blind, randomized-controlled trials in patients with diagnosed schizophrenia who were prescribed an antipsychotic medication. The studies needed to evaluate the impact of metformin on reversing or preventing antipsychotic-induced weight gain.

Overall, 3968 unique records were found; 19 were eligible for inclusion; and 8 were used in addition to 12 trials found in a previous review. Across the 20 studies analyzed, there were 1070 patients. The daily metformin dosage ranged from 500 to 2550 mg and treatment regimens ran from 12 to 24 weeks. The mean age of participants at diagnosis ranged from 13 to 47 years with three studies focusing on children and adolescents.

In this meta-analysis, the researchers found that patients taking metformin had significant reductions in weight, BMI, fasting glucose level, and insulin resistance index. The mean difference (MD) for weight change was −3.32 kg (95% CI −4.57 to −2.07); -1.24 kg/m², 95% CI -1.70 to -0.77 for BMI; -0.47 mg/dl, 95% CI -0.92 to -0.01 for fasting blood glucose; and -1.43, 95% CI -2.17 to -0.69 for insulin resistance index. P values were <0.05 across all measures.

Additionally, metformin reduced body weight by -2.87 kg (95% CI -5.37 to -0.37) in patients who had never taken an antipsychotic drug and in patients receiving antipsychotics for a first episode (MD -6.10 kg; 95% CI -6.97 to -5.22) or chronic schizophrenia (MD -2.84 kg; 95% CI -4.32 to -1.36). Similar trends were noted for all measures in patient BMI.

Doses ≤1000 mg/day and (>1000 mg/day) were both effective, and efficacy was maintained across various treatment durations; weight loss at 12 weeks of therapy was not signifi­cantly different than weight loss observed at 24 weeks of therapy.

The concluded stating, “Such research will enhance clinical manage­ment and improve the quality of life for patients with schiz­ophrenia and associated metabolic complications.”

The primary limitations of the study include the fact that 6 out of the 20 studies had a high risk of bias and that there was heterogeneity in the subgroup analyses.

This article originally appeared on Psychiatry Advisor