Studies show that avoiding long-time fasting by oral carbohydrates 2 hours before surgery attenuates discomfort and anxiety; it also reduces stress, insulin resistance and catabolism in patients undergoing gastrointestinal surgery, resulting in earlier recovery of gastrointestinal function and short length of hospital stay after surgery. However, for diabetic patients scheduled to undergo gastrointestinal surgery, the risks and benefits of preopertive oral carbohydrate remain unclear. The purpose of this pilot study is to investigate the impact of preoperative oral carbohydrate (outfast®) on the recovery in diabetic patients after gastrointestinal surgery.