Impact of metformin on anti-Müllerian hormone in women with polycystic ovary syndrome: a secondary analysis of a randomized controlled trial.

Conclusions on the effect of metformin on circulating anti-Müllerian hormone (AMH) levels in women with polycystic ovary syndrome (PCOS) are ambiguous. We performed a secondary analysis of a randomized, double-blind, placebo-controlled cross-over trial. Fifty-six women with hyperandrogenemic PCOS were included. Each woman served as her own control receiving a daily dose of either 1700 mg metformin or placebo for 6 months. After a 3-month wash-out period they received the opposite treatment. The decrease in AMH from a median of 49.5 to 46.9 pmol/L after 6 months on metformin was overall not significant (p = 0.81), nor were changes in obese women (from 49.5 to 38.2 pmol/L; p = 0.53). Comparing individual metformin/placebo AMH values, a small absolute decrease of 9.3 pmol/L (p = 0.03) was observed in obese women after 6 months relative to baseline, suggesting a trend towards decreasing values after metformin treatment, mainly in obese women.