Insulin resistance: what is its role in PCOS?

Insulin resistance and associated hyperinsulinemia are common features of polycystic ovary syndrome (PCOS). There is evidence that hyperinsulinemia, in susceptible individuals, may play a major pathogenetic role by increasing free androgen levels. However, it remains unclear whether these alterations are primary or secondary defects. Increased exposure to androgens may contribute to impairing insulin action, generating vicious cycles in which it is difficult to recognize the initial defect. Moreover, distinct genetic and environmental mechanisms may be responsible for insulin resistance in different individuals. These women show several risk factors of cardiovascular disease, typically associated with insulin resistance. Recent data support the hypothesis of increased cardiovascular risk in these women, but there is still no definite proof of this. Large prospective studies should assess whether cardiovascular risk actually increases in these women, focusing on the specific role of insulin resistance and associated features in this phenomenon.