The aim of this study is to evaluate evaluated the impact of preoperative HbA1c in diabetic patients on perioperative glycemic variability and outcome after off-pump coronary artery bypass (OPCAB).

The medical records of patients who had a preoperative diagnosis of diabetes and underwent OPCAB from 2005 to 2017 will be reviewed. Patients are divided by HbA1c levels (<7.0% or ≥7.0%). Glycemic variability during surgery and up to 24 hours after surgery is assessed by the coefficient of variation. The primary outcome is defined as a composite of postoperative permanent stroke, prolonged ventilation, deep sternal wound infection, renal failure, reoperation, mortality according to the definition of STS (Society of Thoracic Surgery) version 2.81 adult cardiac surgery database. If one or more of the above five morbidity or mortality occur, it is assumed that composite morbidity/mortality had occurred. We compare postoperative complications, mortality and perioperative glycemic variability between patients with HbA1c ≥7.0% and <7.0%, and examined the effects of perioperative glycemic control on postoperative morbidity and mortality (composite morbidity/mortality).

Inclusion Criteria:

• Patients with a history of preoperative diabetes mellitus and with available results of HbA1c test within 3 months before surgery.
• Patients who aged 20 to 89 years

Exclusion Criteria:

• Patient who had a history of previous coronary artery bypass surgery
• Patients whose surgery plan changed to cardiopulmonary bypass during surgery.

Patients with a history of preoperative diabetes mellitus