Objective To study the effect of intraoperative glucose and insulin infusion on the metabolism in patients undergoing esophageal cancer surgery under combined general anesthesia with epidural block. Methods Twenty ASA physical status Ⅰ-Ⅱ adult patients undergoing esophageal cancer surgery were studied. Ten patients received an iv glucose infusion at 0.5 g·kg~(-1)·h~(-1) and insulin infusion (1-1.5 IU ∶ 1 g glucose) throughout the anesthesia. Ten control subjects received isovolumic nutrient-free saline solution. Rectal temperature, plasma glucose concentrations, plasma free fatty acid (FFA) concentrations, plasma potassium concentrations and 24 hour urea nitrogen were measured perioperatively. Results No statistical difference was observed in rectal temperature and 24 hour urea nitrogen between the two groups. The plasma glucose concentrations continued to increase perioperatively in the control group. The glucose concentration increased during the operation in the glucose/insulin group, but the glucose concentrations at 1 and 2 hours after the operation were not statistically different from that before operation. Significant difference in plasma FFA concentration was found perioperatively (30, 90, 120, 150 min during the operation compared with 1 h after operation) between the two groups. In the glucose/insulin group, there was a significant decrease in the concentration of plasma potassium at 1 and 2 h during and after the operation. Conclusions Intraoperative glucose and insulin infusion cannot prevent hypothermia in patients undergoing esophageal cancer surgery under combined general anesthesia with epidural block, however, it may reduce lipoclasis.