Metformin effects on ovarian ultrasound appearance and steroidogenic function in normal-weight normoinsulinemic women with polycystic ovary syndrome: a randomized double-blind placebo-controlled clinical trial.

OBJECTIVE: To investigate metformin effects on the endocrine-metabolic parameters and ovarian morphology in normoinsulinemic women with polycystic ovary syndrome (PCOS). DESIGN: Randomized double-blind study. SETTING: Operative Division of Endocrinological Gynecology, Università Cattolica del Sacro Cuore. PATIENT(S): Twenty-eight normal-weight normoinsulinemic PCOS women. INTERVENTION(S): Patients were randomized to receive metformin 500 mg twice a day (group A, 15 subjects) or placebo (group B, 13 subjects) for 6 months. Ultrasonographic pelvic exams, hormonal and lipid features, and oral glucose tolerance test were performed at baseline and after 3 and 6 months of treatment. MAIN OUTCOME MEASURE(S): Hormonal and glycoinsulinemic assessment, ovarian ultrasound appearance. RESULT(S): Glycoinsulinemic assessment remained unvaried in both groups. About 70% of patients in group A experienced a restoration of menstrual cyclicity. Metformin significantly decreased testosterone levels at 3 and 6 months) and 17-hydroxyprogesterone levels at 6 months, and improved hirsutism score at 6 months. No clinical or hormonal modifications occurred in group B. Metformin, but not placebo, reduced ovarian volume and stromal/total area ratio at 3 and 6 months. CONCLUSION(S): Metformin seems to improve the menstrual pattern and ultrasonographic ovarian features in normoinsulinemic PCOS women. These effects seem to be, at least in part, independent of the insulin-lowering properties of the drug.