Diabetes in patients undergoing coronary artery bypass grafting. Impact on perioperative outcome

Diabetes mellitus is an established risk factor related to significant morbidity and mortality after coronary artery bypass grafting. Data on 9682 patients undergoing coronary artery bypass grafting either with (n=8917) or without cardiopulmonary bypass (off-pump coronary artery bypass grafting; n=765) were subjected to an univariate analysis to identify potential associations between diabetes mellitus and 26 a priori selected perioperative outcome variables. Those having a significant association with diabetes were then subjected to a stepwise logistic regression model to identify the impact of diabetes as compared to additional 22 different a priori chosen patient related risk factors and treatment variables. Prevalence of outcome variables independently associated with diabetes has been determined in the subgroup of diabetics undergoing coronary artery bypass grafting with cardiopulmonary bypass or off-pump coronary artery bypass grafting surgery to evaluate the effect of avoiding cardiopulmonary bypass on perioperative patient outcome. Diabetes mellitus was defined as glucose intolerance either treated dietary, with oral hypoglycemics or with insulin. According to this definition of diabetes mellitus we found an overall prevalence of 37.1% (coronary artery bypass grafting with cardiopulmonary bypass: 37.5%; off-pump coronary artery bypass grafting: 32.5%). Eleven outcome variables having a significant association with diabetes were identified. Diabetes could be identified as an independent predictor of postoperative delirium, renal dysfunction and respiratory insufficiency. Prevalence of these three variables was lower in diabetics undergoing off-pump coronary artery bypass grafting as in those undergoing coronary artery bypass grafting with cardiopulmonary bypass surgery reaching statistical significance with regard to postoperative delirium and respiratory insufficiency. In conclusion, diabetes mellitus is a significant independent predictor for three postoperative outcome variables in coronary artery bypass surgery. Avoiding cardiopulmonary bypass in diabetics seems to have a beneficial effect.