Polycystic ovary syndrome (PCOS) is the commonest cause of menstrual disorder in teenagers. Insulin resistance reportedly is associated with high androgen levels and related symptoms including anovulation and oligomenorrhea. More than half of teenage girls with PCOS are obese, and many of them later develop type 2 diabetes. This study assessed the effects of the insulin-lowering drug metformin in 18 obese girls 15–18 years of age who received a diagnosis of PCOS based on consensus criteria. Starting on days 6–8 of induced menstrual bleeding, participants received metformin in tablet form in a daily dose of 1700 mg for 6 months and were followed for 6 months longer.
Two girls withdrew from the study because of side effects. The remaining 16 had improved menstrual cyclicity during follow-up. Once-a-month menstrual bleeding returned within 30 days of the start of the second month of treatment. The menstrual periods were ovulatory, as evidenced by increased luteal-phase progesterone levels and significantly lower androgen concentrations. Hirsutism decreased significantly, and in several instances acne and seborrhea were alleviated. Body mass indices decreased to within normal limits in all girls. Levels of luteinizing hormone (LH) and the LH/follicle-stimulating hormone (FSH) ratio decreased significantly, while levels of sex hormone-binding globulin rose significantly. Levels of total testosterone, free testosterone, and androstenedione all declined significantly during metformin therapy. Basal fasting insulin levels during treatment were less than 5 mIU/liter. Ovulation continued during follow-up, with progesterone levels exceeding 5000 pg/mL in all instances.
Metformin has favorable effects on ovulation in moderately obese adolescents with PCOS. It may well be a more appropriate treatment than estrogen and progestin in these patients, not only promoting ovulation but relieving symptoms of hyperandrogenism.