Objective To assess the tolerance of preoperative carbohydrate-rich beverage, to determine its effect on postoperative insulin resistance and analyze its potential mechanism. Methods Thirty-two patients undergoing elective colorectal cancer resection were recruited to this randomized controlled study and assigned to two groups at random. Patient in control group was fasted before operation, while patient in study group was given oral water. Homeostasis model assessment (HOMA) indexes, activity of PTK, and mRNA and (or) protein expressions of PKB, PI3K and GluT4 were measured before and (or) immediately after surgery. Furthermore preoperative well-beings of patients were studied. Results Among well-beings, feeling of thirst, hunger and anxiety tended to be better in patients receiving carbohydrate-rich beverages compared with fasted ones (P＜0.05). Whole body insulin sensitivity decreased by 33% in the study group while 38% in the control group (P=0.007 2), and the activity of PTK, expressions of PI3K and PKB in study group were higher than those in control group (P＜0.05， P＜0.01), but no significantly difference was observed about GluT4 in both groups (Pgt;0.05）. Conclusion Preoperative consumption of carbohydrate-containing fluids is safe and effective. Provision of carbohydrate energy source prior to surgery may attenuate immediate postoperative insulin resistance. A carbohydrate-rich drink enhances insulin action at the time of onset of anaesthesia or surgery by activating three kinases named PTK, PI3K, PKB which are key enzymes in pathway of insulin signal transduction. It is likely to explain the effects on postoperative insulin resistance.