Abstract： Objective To investigate the effect of diabetes on the prognosis, complications and medical cost in the patients with abdominal surgery. Methods To analyze the clinical data of 68 diabetic patients with abdominal surgery and the relationship among the average hospitalized length, medical cost and the complications of surgery due to hyperglycemia. Results Comparing with controls, diabetic patients had 13, 2, 3, and 3 days longer at the time of in hospital duration, stitch removing, food taking and using antibiotics after the operation, with significantly higher complications and higher in hospital medical cost. Diabetics with fasting blood glucose level less than 8 mmol/L before operation had no complications of surgery and much lower medical cost, and diabetics with higher blood glucose level had more complications (17.5%). Conclusion To intensify monitoring and control of blood glucose in the diabetic patients with abdominal surgery is very important for improving prognosis, and decreasing the complications and medical cost of the operation.