The past 20 years have witnessed a remarkable increase in our knowledge of the cellular and molecular mechanisms that underlie the diverse actions of insulin, the central hormone of metabolic regulation. Interest in the molecular details of insulin action has been heightened by the prevalence of insulin resistance and by the fact that insulin resistance has a key role in the pathogenesis of many disorders, including obesity, diabetes mellitus, ovarian hyperan-drogenism, and possibly hypertension. In this review, we discuss current concepts of the mechanisms of insulin action and insulin resistance and the implications of insulin resistance for a variety of . . .