NEW YORK (Reuters Health) Mar 24 - Oral contraceptives improved features of polycystic ovary syndrome (PCOS) in adolescent girls but have an unfavorable impact on insulin resistance, according to a report in the February issue of Fertility and Sterility.

Adolescent girls with PCOS often have reduced insulin sensitivity, hepatic insulin resistance, and compensatory hyperinsulinemia, the authors explain. Oral contraceptives may worsen these features.

Dr. George Mastorakos and colleagues from Athens University School of Medicine, investigated the effect on carbohydrate metabolism of two combined oral contraceptives containing cyproterone or desogestrel as progestogenic compounds in 36 adolescent girls with PCOS.

Although body mass index and waist-to-hip ratio remained unchanged during treatment, three patients developed impaired fasting glucose and another three patients developed impaired glucose tolerance after 12 months of treatment, the authors report.

The fasting glucose-to-insulin ratio declined after 12 months of treatment in both groups, the results indicate, although the decline was statistically significant only in the cyproterone group. Similarly, the insulin sensitivity index decreased significantly and insulin secretion increased significantly only in the cyproterone-treated group.

"Both combined oral contraceptive formulations are effective in ensuring normal menstrual cyclicity and in reducing hirsutism in adolescent patients with PCOS," the authors note. "Both treatments have an unfavorable impact on insulin resistance. However, as has been suggested in the past, this effect is not translated into a clinically relevant major impact."

"The positive correlation between insulin values and body mass index in women with PCOS suggests that obese teenage patients, along with psychological support, should also be encouraged to lose weight and exercise in an effort to improve the clinical and metabolic features of the syndrome," the researchers conclude.