Surgical stress creates a state of insulin resistance which has been related to increased postoperative complications. Fasting before surgery induces a catabolic state that contributes to the development of insulin resistance. The aim of this study is to evaluate the effect of preoperative oral carbohydrates on postoperative insulin resistance in patients undergoing OPCAB (off-pump coronary artery bypass surgery). Sixty patients, aged 20 to 79 years, scheduled for OPCAB will be divided into carbohydrate (n=30) and control (n=30) groups. Randomly selected patients of the carbohydrate group are given 400ml of 12.8 g/100 ml carbohydrate beverage in the evening before surgery and in the morning of the operation day (3 hours before their scheduled operation). In contrast, patients in the control group consume no food or drink after midnight before their surgery. The primary endpoints are postoperative insulin resistance measured by short insulin tolerance test.

Inclusion Criteria:

• patients who are scheduled to undergo OPCAB

Exclusion Criteria:

• Subjects are ineligible if they have DM(Diabetes Mellitus),
• Gastroesophageal reflux disease or gastric emptying disorder,
• inflammatory bowel disease,
• previous treatment for intra-abdominal cancer,
• entered surgery more than 5 hours after ingestion of the morning carbohydrate beverage,
• cognitive dysfunction,
• disabling mental change disorder,
• are unable to communicate or speak Korean