Diabetes mellitus (D.M.) is a group of metabolic diseases characterized by hyperglycemia resulting from defects in insulin secretion, insulin action, or both. The chronic hyperglycemia of diabetes is associated with long-term damage, dysfunction, and failure of various organs, especially the eyes, kidneys, nerves, heart, and blood vessels. Because of the distribution of diabetes mellitus and the little studies that concerns by subjects suffer from diabetes mellitus especially type 2 in Iraq, we went to study some of physiological and biochemical changes in patients with type 2 diabetes mellitus.