Insulin sensitivity and fertility.

This review sets in context significant recent advances in the understanding of the pathophysiology of polycystic ovary syndrome (PCOS). The occurrence of variable insulin sensitivity in individuals is discussed. Information is presented to demonstrate that prolonged anovulation decreases insulin sensitivity and, conversely, that improvement in insulin sensitivity normalizes ovarian function in PCOS. In addition, a meta-analysis of studies on metformin and troglitazone treatment in PCOS is presented.