The effect of metformin on fat distribution and the metabolic syndrome in women with polycystic ovary syndrome—a randomised, double‐blind, placebo‐controlled trial

Abstract

OBJECTIVE: To establish whether metformin has a significant action in reducing visceral fat and improving other metabolic parameters in women with polycystic ovary syndrome (PCOS). DESIGN: Randomised, double-blind, placebo-controlled trial. SETTING: Reproductive medicine clinic. POPULATION: Forty women with anovulatory PCOS. METHODS: Participants were randomised into receiving metformin 500 mg three times a day or placebo for 3 months. MAIN OUTCOME MEASURES: Fat distribution was measured by computed tomography scan. Secondary outcome measures included serum indices of the metabolic syndrome and evidence of ovulation. RESULTS: We found no significant differences in any of the measures of fat distribution between the placebo and metformin groups. The metformin group had significantly lower total cholesterol (P= 0.02), low-density lipoprotein cholesterol (P= 0.02) and cholesterol:high-density lipoprotein cholesterol ratio (P= 0.05), but there was no statistically significant treatment effect on androgens, insulin, insulin resistance, triglycerides, ovulation or pregnancy. CONCLUSIONS: Metformin has no clinically significant effect in reducing visceral fat mass, although it does have a beneficial effect on lipids. This trial lends support to the growing evidence that metformin is not a weight loss drug. Metformin might therefore be used as an adjunct to lifestyle modification in women with PCOS, but not as a substitute for it.