A study of postoperative glucose metabolism in eight diabetic and 23 nondiabetic patients undergoing operations on the lower extremity showed the following changes: elevated fasting levels of glucose and unesterified fatty acids, most marked two days after surgery; one hour after dextrose ingestion the blood glucose level in diabetics was below preoperative levels while in the nondiabetics it was elevated. Both diabetics and nondiabetics showed a delayed fall of the blood glucose to fasting levels. Postoperative insulin concentrations were elevated in nondiabetic and suppressed in diabetic patients. Both 17-hydroxycorticosteroid and growth hormone levels were elevated in the postoperative period. It is possible that they influenced the observed changes in glucose metabolism.