Blood sampling

Blood sampling was performed in control women during the follicular phase (days 5–10 of the menstrual cycle) and in PCOS women during documented oligo- anovulation by serum P4 level. Fasting blood samples were collected immediately before a frequently sampled intravenous glucose tolerance test (FSIGT) as previously described (7, 23) to determine total and free T, androstenedione (A4), dihydrotestosterone (DHT), dehydroepiandrosterone sulfate (DHEAS), gonadotropins, estrone (E1), estradiol (E2), glucose, insulin, sex hormone binding globulin (SHBG) and lipid (total cholesterol, high density lipoprotein [HDL], low density lipoprotein [LDL], triglycerides [TG]) levels. The modified minimal model of Bergman was used to define insulin sensitivity (Si) (23).