Metabolic effects of oral contraceptives in women with polycystic ovary syndrome

Insulin resistance and dyslipidemia have been described in women with polycystic ovary syndrome (PCOS), a disorder characterized by hyperandrogenism and oligomenorrhea. Although oral contraceptives (OC) are often instituted to regulate menses and suppress HA in women with PCOS, their use has been postulated to cause a deterioration in insulin sensitivity and to adversely affect circulating lipids. To investigate these effects, 9 women with PCOS and 10 age- and weight-matched control women were studied before and during the third month of therapy with a low-dose norethindrone-containing triphasic combination OC using the hyperglycemic clamp technique. At baseline, the PCOS group had higher androgen, triglyceride, and glycosylated hemoglobin concentrations, with a greater insulin response to oral glucose and a lower insulin sensitivity index (ISI) than controls. During OC therapy, a reduction in ISI was observed in both groups, whereas an increase in triglycerides was observed only in controls, removing any observed difference between the two groups in ISI or lipids. In women with PCOS, an increase in insulin concentrations during hyperglycemia accounted for the decline in ISI (P = 0.026), whereas in control women the decrease in ISI was attributable to a decrease in glucose disposal (P = 0.004). In conclusion, PCOS is characterized by insulin resistance in the untreated state. Short-term therapy with a triphasic OC results in a further decline in ISI in women with PCOS, without inducing additional adverse effects on lipids. A more pronounced decline in ISI together with an elevation in triglyceride levels occurs in normal women with OCs. The mechanisms leading to this decrease in ISI are different for each group.