Biochemical and molecular basis of insulin resistance

Insulin-resistance is a major problem associated with diabetes and that is increasing rapidly worldwide. Insulin is a peptide hormone secreted by the beta-cells of the pancreatic islets of Langerhans in response to increased circulating levels of glucose and amino acids and it is essential for appropriate tissue development, growth, and maintenance of whole-body glucose homeostasis by regulating carbohydrate, lipid and protein metabolism. Insulin resistance is a defect in signal transduction. The signaling mechanisms involved in the various biologic responses to insulin remain somewhat elusive. This review focuses on the structure and activity of insulin receptor, inheritance of insulin resistance, insulin receptor and alleles, enzyme activity in insulin resistance, insulin receptor in phosphorylation and relating substrate. We have discussed insulin receptor substrate-family (IRS) related to insulin resistance, detail downstream signaling effects, GLUT4 vesicle translocation and related events, cytokine-mediated insulin resistance, and feedback control mechanisms. This review also focuses on insulin resistance in obesity-linked metabolic syndrome, insulin resistance related to plasma membrane disturbances and insulin resistance for exercise and cellular integrity. Finally, we can conclude that insulin resistance is really a complex phenomenon in which several genetic defects combine with environmental stresses.