Insulin resistance and hyperinsulinemia plays a pivotal role in the pathogenesis of polycystic ovary syndrome (PCOS). Hyperinsulinemia stimulates ovarian cytochrome P450c17 alpha activity, in obese and nonobese women with PCOS, thereby increasing serum levels of 17-alpha-hydroxyprogesterone, androgens concentrations, decreasing SHBG and promoting the clinical features of hyperandrogenism.