Women with polycystic ovary syndrome (PCOS) are at increased risk of developing diabetes mellitus type 2. Insulin resistance plays a key role in the predisposition to diabetes in PCOS; however, defects in insulin secretion also appear to contribute to its development. Since diabetes mellitus is not a universal consequence in PCOS, however, it is important to develop means to identify those women who are at highest risk. In this way, it may become possible to delay or even prevent the onset of diabetes mellitus in later life. Identification of genetic factors and use of pharmacological agents may allow early identification of those women with PCOS who are at greatest risk for development of diabetes mellitus type 2.