Patients with diabetes are more likely to undergo surgery than nondiabetics, and maintaining glycemic control in subjects with diabetes can be challenging during the perioperative period. Surgery in diabetic patients is associated with longer hospital stay, higher health care resource utilization, and greater perioperative mortality. In addition, several observational and interventional studies have indicated that hyperglycemia is associated with adverse clinical outcomes in surgical and critically ill patients. This paper reviews the pathophysiology of hyperglycemia during trauma and surgical stress and will provide practical recommendations for the preoperative, intraoperative, and postoperative care of diabetic patients.