Background & Aims: Insulin sensitivity often decreases after surgery in spite of normal insulin secretion, and may worsen the outcome. This post-operative insulin resistance increases according to the magnitude of surgical invasion. However, supplementation of carbohydrates before surgery attenuates the post-operative insulin resistance. This study aimed to investigate the effect of intra-operative administration of low-dose glucose on the post-operative insulin resistance. Methods: Patients undergoing maxillofacial surgery were randomly assigned to two groups throughout the surgical procedure: The glucose group receiving acetated Ringer solution with 1.5% glucose and the control group receiving acetated Ringer solution without glucose. Insulin resistance quantified by the mean glucose infusion rate (the glucose infusion rate) was evaluated by glucose clamp using the STG-22TM instrument on the previous day and on the next day of surgery. Blood glucose level was monitored continuously during surgery. In addition, serum insulin, ketone bodies and 3-methylhistidine were measured during perioperative period. Results: Patients in the glucose group (n=11) received 0.15±0.06 g/kg/h of glucose during surgery, while patients in the control group (n=11) received no glucose. In both groups, however, the mean blood glucose levels were maintained stable at less than 150 mg/dL during and after surgery. The serum ketone bodies significantly increased after surgery in the control group (p=0.0035), while it decreased significantly in the glucose group (p=0.043). The reduction rate in the glucose infusion rate was significantly lower in the glucose group, 43.3±20.7%, than that in the control group, 57.7±9.3% (p=0.041). Conclusions: Intra-operative small-dose of glucose administration may suppress ketogenesis and attenuate the post-operative insulin resistance without causing hyperglycemia.