Menstrual cyclicity after metformin therapy in polycystic ovary syndrome

Objective: To assess the effect of insulin-lowering treatment on menstrual cyclicity in polycystic ovary syndrome (PCOS). Methods: Forty oligoamenorrheic women with PCOS were recruited in a prospective clinical study to receive metformin for a minimum period of 6 months. Twenty-two women completed the study. Serum LH, FSH, free testosterone, and glucose and insulin response to oral glucose load were measured both before and after 8 weeks of metformin treatment. Menstrual cyclicity and serum progesterone levels at the midluteal phase were assessed at the 30th week of metformin treatment. Results: Twenty-one of 22 women had restoration of menstrual cyclicity (95.7%). Four of these women (19%) became pregnant within the 6th and 7th months of treatment. All four of the pregnant women delivered, and the infants were healthy. Thirteen of 15 women who had regular menses demonstrated a serum progesterone level within the ovulatory range (3.1-28 ng/mL). Fasting (P < .001) and the integrated insulin response to the glucose load decreased (P < .001) after 8 weeks of metformin treatment. This was accompanied by significant decreases in serum LH (P < .001) and free testosterone (P < .001) levels and LH/FSH ratio (P < .001). There was a small but significant reduction in body mass index after 8 weeks of metformin treatment (P < .001). Conclusions: A 6-month course of metformin may improve menstrual cyclicity and fertility in women with the PCOS. Insulin-sensitizing agents provide a rational approach to the treatment of the metabolic and endocrine abnormalities in PCOS women. (C) 1997 by The American College of Obstetricians and Gynecologists.