Impact of tight glucose control on postoperative infection rates and wound healing in cardiac surgery patients.

Approximately 1 of every 4 hospitalized patients has diabetes mellitus (DM). Type 2 DM is commonly associated with cardiovascular disease, and many undergo cardiothoracic surgical procedures such as coronary artery bypass grafting. Persons with type 2 DM are at higher risk for postoperative infections due to a muted immune response, the effects of hyperglycemia on neutrophil function and pathogen proliferation, and the negative effects of diminished perfusion. Hyperglycemia resulting from insulin resistance is common in critically ill patients, including those who have not previously been diagnosed with diabetes. Factors contributing to postoperative hyperglycemia include increased levels of catecholamines, growth hormone, and corticosteroids. Higher glucose levels may also result from pharmacologic agents commonly used during and following surgery, such as heparin and beta-blockers. Tight glucose control has been shown to improve survival and reduce morbidity after cardiac surgery and lower the incidence of wound complications. In contrast, the traditional approach to glucose management, sliding-scale insulin administration, does not provide adequate control. Continuous insulin infusion protocols may significantly reduce postoperative morbidity and mortality in patients with type 2 DM and hyperglycemia associated with metabolic syndrome.