Hyperinsulinemia in polycystic ovary syndrome correlates with increased cardiovascular risk independent of obesity

OBJECTIVE: To assess the role of insulin resistance, independent of obesity, in determining cardiovascular risk among women with the polycystic ovarian syndrome (PCOS). DESIGN: Cross-sectional study examining the relationships between hyperinsulinemia, composite cardiovascular risk scores, and prevalence of individual risk factors among lean and obese women with PCOS and healthy controls. SETTING: University-based tertiary care outpatient endocrinology clinic. PATIENT(S): 57 women with clinically defined PCOS and 45 unselected healthy age-matched controls. INTERVENTION(S): Clinical and anthropomorphic measurements and laboratory determinations of insulin and lipid levels. MAIN OUTCOME MEASURE(S): Fasting serum insulin and a cardiovascular risk score. RESULTS: Hyperinsulinemic women with PCOS carried more cardiovascular risk than their normoinsulinemic counterparts, who in turn had more risk than the control women (P=.004 by analysis of covariance). In addition to the lipid changes expected with insulin resistance (high triglyceride and low HDL cholesterol levels), there was an excess of LDL cholesterol among the women with PCOS (P=.006 by analysis of covariance). Across the range of body mass index, women with PCOS had greater insulin resistance than controls, suggesting that PCOS itself and body mass index both contribute to the observed insulin resistance. CONCLUSIONS: Our data support the hypothesis that insulin resistance in PCOS is a determinant of overall cardiovascular risk independent of obesity. The mechanism of this relationship remains uncertain and is the subject of ongoing research.