Preoperative oral carbohydrate administration reduces postoperative insulin resistance

Infusions of carbohydrates before surgery reduce postoperative insulin resistance. We investigated the effects of a carbohydrate drink, given shortly before surgery, on postoperative metabolism. Method: Insulin sensitivity, glucose turnover ([6,6, ²H₂]-D-glucose) and substrate utilization were measured using hyperinsulinemic normoglycemic clamps and indirect calorimetry in two matched groups of patients before and after elective colorectal surgery. The drink group (n = 7) received 800 ml of an isoosmolar carbohydrate rich beverage the evening before the operation (100 g carbohydrates), as well as another 400 ml (50 g carbohydrates) 2 h before the initiation of anesthesia. The fasted group (n = 7) was operated after an overnight fast. Results: After surgery, energy expenditure increased in both groups. Endogenous glucose production was higher after surgery and the difference was significant during low insulin infusion rates in both groups (P < 0.05). The supressibility of endogenous glucose production by the two step insulin infusion was similar pre- and postoperatively in both groups. At the high insulin infusion rate postoperatively, whole body glucose disposal was more reduced in the fasted group (-49 ± 6% vs -26 ± 8%, P < 0.05 vs drink). Furthermore, during high insulin infusion rates, glucose oxidation decreased postoperatively only in the fasted group (P < 0.05) and postoperative levels of fat oxidation were greater in the fasted group (P < 0.05 vs drink). Only minor postoperative changes in cortisol and glucagon were found and no differences were found between the treatment groups. Conclusions: Patients given a carbohydrate drink shortly before elective colorectal surgery displayed less reduced insulin sensitivity after surgery as compared to patients who were operated after an overnight fast.