Up to 40% of women with polycystic ovary syndrome (PCOS) demonstrate some degree of glucose intolerance, either impaired glucose tolerance (IGT) or non-insulin dependent diabetes mellitus (NIDDM). Defects in insulin action have long-been recognized as characteristic in these women. Recently, evidence has been obtained which documents that insulin secretory dysfunction also contributes significantly to the observed glucose intolerance. This chapter will focus on the recent evidence supporting the specific roles of disordered insulin secretion and action, in the development of glucose intolerance in PCOS. In addition, the use of pharmacological agents that modify insulin action as therapeutic options for women with PCOS, will be discussed.