The good, the bad, and the ugly facets of insulin resistance.

Insulin is a potent anabolic hormone, and binding to its receptor activates downstream intracellular signaling pathways that regulate the nutrient metabolism, fluid homeostasis, growth, ionic transport, maintenance of vascular tone, and other functions. Insulin resistance (IR) is a condition characterized by subnormal cellular response to physiological levels of insulin. The IR is divided into three types (prereceptor, receptor, and postreceptor) based on the site of pathology. Beta cells attempt to overcome the IR by increasing the release of insulin, leading to hyperinsulinemia. IR is the predisposing factor for many metabolic and cardiovascular disorders. From the evolutionary perspective, the presence of IR offers a survival advantage in the face of starvation or stress. In this brief review, we discuss the different facets of insulin resistance and appraise the readers about the hitherto neglected beneficial advantages.