Objective To observe the feature of post-operative hyperglycemia after coronary artery bypass grafting(CABG) surgery in department of intensive care unit（ICU） patients.Methods Patients who had CABG surgery in Zhongshan Hospital from January 2005 to December 2005 were enrolled.Data were collected including the history of diabetes，pre-operative and post-operative blood glucose(BG) levels，and the time that post-operative hyperglycemia and peak BG occurred.The patients were divided into diabetic and non-diabetic groups according to the diabetic history.The data were compared and analyzed between the two groups.Results 200 patients were enrolled in this study.The incidence of post-operative hyperglycemia was 77%，and about 99.4% occurred in the first 24 hours admitted to ICU，which was independent on diabetic history (χ2=2.58，P=0.108)，but was related to the BG level above 6.1 mmol/L (χ2=12.31，P=0.000).In 80% of the patients，peak BG occurred in the first 24 hours admitted to ICU，which was significantly earlier in the non-diabetic group compared with the diabetic group (8.5 h vs 18.5 h，P=0.02 ).In the patients who had post-operative hyperglycemia，the median time of the BG peak is 10 hours，and 75.3% of the BG peak occurred in the first 24 hours admitted to ICU.Conclusion There is a high incidence of post-operative hyperglycemia in post-CABG patients which always occur within 24 hours after operation and relate to pre-operative high BG.