Metformin, a
biguanide antihyperglycemic drug, has been shown to improve ovarian function and
glucose metabolism in women with
polycystic ovary syndrome (PCOS), but results concerning its effects on
insulin sensitivity are controversial.
Oral contraceptive pills are commonly used in the treatment of PCOS; but, like
metformin, their influence on
insulin sensitivity is not well known. We randomized 32 obese (body mass index > 27 kg/m2) women with PCOS, either to
metformin (500 mg x 2 daily for 3 months, then 1,000 mg x 2 daily for 3 months) or to
ethinyl estradiol (35 microg)-cyproterone
acetate (2 mg)
oral contraceptive pills (Diane Nova) for 6 months.
Metformin significantly decreased the waist-to-hip ratio, serum
testosterone, fasting
free fatty acid, and
insulin concentrations and improved oxidative
glucose utilization and menstrual cyclicity, with slight (but nonsignificant) improvements in
insulin hepatic extraction and
insulin sensitivity. Diane Nova significantly decreased serum
testosterone and increased serum
sex hormone-binding globulin concentrations and
glucose area under the curve during oral
glucose tolerance test. It is concluded that
metformin, probably by way of its effect on adipose tissue, leads to reduction of
hyperinsulinemia and concomitant improvement in the menstrual pattern; and therefore, it offers a useful alternative treatment for obese, anovulatory women with PCOS. Despite slight worsening of
glucose tolerance, Diane Nova is an efficient treatment for women with
hyperandrogenism and
hirsutism.