Metformin for Treatment of Antipsychotic-Induced Amenorrhea and Weight Gain in Women With First-Episode Schizophrenia: A Double-Blind, Randomized, Placebo-Controlled Study

Women who experienced amenorrhea during their first antipsychotic treatment for schizophrenia also received metformin, 1000 mg/day, for 6 months in a double-blind placebo-controlled study. Two-thirds of metformin-treated patients, compared to 5% of placebo-treated patients, resumed menstruation. Metformin-treated patients had a mean decrease in body mass index (BMI) of 0.93 and a mean change in insulin resistance index of 2.04. In contrast, placebo-treated patients had a mean increase in BMI of 0.85. Prolactin, luteinizing hormone, and testosterone levels and the ratio of luteinizing hormone to follicle-stimulating hormone decreased significantly with metformin. Metformin had no significant adverse effects.