HbA1c and diabetes predict perioperative hyperglycemia and glycemic variability in on-pump coronary artery bypass graft patients.

Objective: Perioperative hyperglycemia and glycemic variability are considered independent predictors of morbidity and mortality in critically ill patients. The purpose of this study was to investigate the relation of HbA1c and/or a prior diagnosis of diabetes mellitus and intra- and postoperative hyperglycemia and glycemic variability.

Design: A retrospective data analysis from a single-center database.

Setting: A single university hospital.

Participants: Diabetic and nondiabetic patients undergoing isolated on-pump coronary artery bypass graft (CABG) surgery.

Measurements: One hundred twenty patients undergoing isolated CABG surgery were evaluated. Glucose values were acquired pre-, intra-, and postoperatively on the day of surgery as well as on the first postoperative day. The extent of hyperglycemia within and between groups was compared using mean and maximum glucose values. As a measure of the patient's individual intra- and postoperative glucose variability, the standard deviation (SD) and the coefficient of variation (CV) of glucose values were calculated. Outcomes were analyzed using a multiple logistic regression model.

Results: Diabetics and/or patients with elevated HbA1c had higher postoperative glucose levels, a higher SD, and a higher CV of postoperative glucose values; however, higher glucose variability was not associated with higher rates of complication. Intraoperative glucose values and variation did not differ significantly between groups. Increased mean blood glucose values were associated with increased risk of infection.

Conclusions: Diabetic status and/or elevated HbA1c are predictors of postoperative glucose variability and hyperglycemia in CABG surgery patients. However, in the intraoperative period, these groups show similar glycemic responses to operative stress.