Objective: To evaluate the effects of metformin on gonadotropin-induced ovulation in patients with polycystic ovary syndrome (PCOS).
Methods: Forty patients with PCOS (study group) and 20 women with normal weight and menstrual cycle (control group) were enrolled. Serum follicle stimulating hormone (FSH), luteinizing hormone (LH), testosterone (T), fasting glucose (FG), fasting insulin (FINS) and fasting leptin were measured before and after treatment. In the study group, 20 cases (group A) were assigned to take 500 mg of metformin three times daily for 12 weeks, if pregnancy did not occur, high purified FSH (FSH-HP) was added for one cycle; another 20 cases (group B) were induced ovulation with FSH-HP alone for one cycle.
Results: There were significant high FINS and leptin levels in the study group as compared with the control group [(20 +/- 16) vs (12 +/- 6) nmol/L, P < 0.05; (14 +/- 16) vs (8 +/- 4) mg/L, P < 0.05]. The obese PCOS group had markedly higher serum FINS and leptin than the non-obese PCOS group [(24 +/- 18) vs (14 +/- 8) nmol/L, P < 0.05; (20 +/- 22) vs (8 +/- 4) mg/L, P < 0.05], but serum FINS and FG were not significantly different between the non-obese PCOS and the control group (P > 0.05). After administration of metformin for 12 weeks, serum LH, T, leptin and FINS decreased significantly (P < 0.05 - 0.01), serum FSH levels and body mass index showed a slight decrease, whereas no change was found in FG. In the study group, 3 cases conceived during metformin therapy, the remaining 37 were induced ovulation with FSH-HP or FSH-HP and metformin, 7 cases obtained pregnancy. The rates of ovulation and pregnancy in group A were higher than those in group B (88% vs 70%, 24% vs 15%), but no significant difference was found.
Conclusions: Metformin therapy in PCOS can decrease the FINS and leptin levels, normalize the endocrine abnormalities, resumes ovulation and pregnancy in some patients, and may improve the ovarian response to gonadotropin.