Diabetes mellitus is an increasingly common disease that affects people of all ages, resulting in significant morbidity and mortality. Diabetic patients require more frequent hospitalization, have greater lengths of stay, and cost more to manage than non-diabetics. The major risk factors for diabetics undergoing surgery are the end-organ diseases associated with diabetes: cardiovascular disease, autonomic neuropathy and immune deficiency. Physicians should pay extra attention to preoperative and preprocedure evaluation and treatment of these diseases to ensure optimal perioperative management. Furthermore, these patients unexpectedly develop hemodynamic instability in response to vasopressor or vasodilator administration during anesthesia, this being of particular importance in patients with concurrent ischemic heart disease in whom it may have a direct effect on mortality. Recent studies have shown that tight glycemic control in diabetic patients undergoing major surgery has been shown to improve perioperative morbidity and mortality.