A Naturalistic Randomized Placebo-Controlled Trial of Extended-Release Metformin to Prevent Weight Gain Associated With Olanzapine in a US Community-Dwelling Population.

Objective: This 24-week pilot study assessed the efficacy, tolerability, and safety of adjunctive metformin versus placebo for the prevention of olanzapine-associated weight gain in community-dwelling adult patients with schizophrenia, schizoaffective disorder, bipolar disorder, or major depression with psychotic features.

Methods: In a double-blind study, 25 patients were randomly assigned to receive 24 weeks of either olanzapine plus metformin or olanzapine plus placebo. Metformin extended release was titrated to 2000 mg daily as tolerated.