Abstract Study Objective To determine whether spinal anesthesia blunts surgical stress reactions and results in less perioperative hyperglycemia. Design Prospective, randomized controlled study. Setting Operating room of a university hospital. Patients 68 adult, nondiabetic (n=40) and diabetic (n=28), ASA physical status 1, 2, and 3 patients patients undergoing elective total hip replacement. Interventions General or spinal anesthesia was administered. Measurements Blood HbA1C was measured preoperatively to identify patients with undiagnosed diabetes. Glucose levels were checked preoperatively, then immediately after, and one hour after surgery. A conventional glucose control protocol was used, where insulin was given when blood glucose concentrations exceeded 250 mg/dL. Main Results Preoperative glucose levels in general and spinal anesthesia patients were comparable and not significantly different in nondiabetic and diabetic patients. At the end of surgery and one hour after surgery, glucose levels were significantly higher in patients undergoing general anesthesia compared with baseline values in both diabetic and nondiabetic patients ( P < 0.05). In nondiabetic and diabetic patients, a significant increase in glucose level was found in patients undergoing general anesthesia versus spinal anesthesia ( P < 0.05). In patients receiving spinal anesthesia, glucose levels remained stable. Two diabetic patients undergoing general anesthesia received insulin. Conclusion Spinal anesthesia attenuates the hyperglycemic response to surgical stimuli in diabetics and nondiabetic patients.