Background: The aim of this study was to investigate the effect of general anaesthesia combined with remifentanil or epidural blockade on glucose metabolism during surgery. Methods: We randomly assigned patients undergoing elective colorectal surgery to receive either desflurane anaesthesia supplemented with intravenous remifentanil (n ¼ 7) or desflurane anaesthesia supplemented with epidural bupivacaine (n ¼ 7). Plasma concentrations of glucose, lactate, free fatty acids (FFA), insulin, glucagon and cortisol were measured before and after 2 h of surgery. Pre-and intraoperative whole body glucose production and glucose clearance, an indicator of glucose uptake, were determined by an isotope dilution technique using [6,6-2 H 2 ]glucose. Results: In both groups intraoperative glucose production ( P< 0.05) and uptake ( P< 0.05) decreased. Plasma glucose concentrations ( P< 0.05) increased during surgery but did not exceed the normal range (remifentanil group: