Metformin therapy improves the menstrual pattern with minimal endocrine and metabolic effects in women with polycystic ovary syndrome.

OBJECTIVE: To determine the clinical, hormonal, and biochemical effects of 4-6 months of metformin therapy in obese patients with polycystic ovary syndrome (PCOS).
DESIGN: Prospective study.
SETTING: The Gynecological Endocrine Unit of University Central Hospital, Oulu, Finland. PATIENT(S): Twenty obese patients with PCOS. INTERVENTION(S): Patients were treated with 0.5 g of metformin three times daily for 4-6 months. MAIN OUTCOME MEASURE(S): Clinical symptoms, menstrual pattern, and hirsutism, as well as serum concentrations of sex steroids, sex hormone-binding globulin (SHBG), gonadotropins, and lipids were assessed during the treatment. RESULT(S): Eleven women (68.8% of the women with menstrual disturbances) experienced more regular cycles during therapy. No changes in hirsutism, body mass index, or blood pressure occurred. The mean testosterone level was decreased significantly after 2 months of treatment but returned to the starting level by 4-6 months. Free testosterone levels decreased significantly during the treatment. There was no significant change in the levels of other sex steroids or lipids measured at 4-6 months of treatment. CONCLUSION(S): Metformin therapy is well tolerated by the majority of patients and may be clinically useful, especially in obese patients with PCOS and menstrual disturbances.