Abstract: Polycystic ovary syndrome （PCOS） causes major metabolic and reproductive morbidities, including substantially increased risk for type 2 diabetes mellitus and the metabolic syndrome. After the recognition that insulin resistance has a pivotal role in PCOS, insulin-sensitizing drugs, specifically metformin, have been widely adopted as therapy for this condition. A recent, large, randomized, clinical trial that assessed live-birth rates suggested that metformin alone is inferior to clomiphene citrate in treating infertility associated with PCOS. Furthermore, there is no evidence to support the use of metformin during pregnancy to prevent spontaneous abortions or gestational diabetes mellitus in women with PCOS. Renewed safety concerns about thiazolidinediones followed recent studies that reported increased cardiovascular events with these agents.

Key words: Infertility, Insulin resistance, Metformin, Polycystic ovary syndrome, Thiazolidinediones