Diabetes mellitus as a risk factor for pulmonary complications after coronary bypass surgery

Objectives: In the past few years there has been increasing evidence that the respiratory function of patients with diabetes is impaired in the course of their disease. The objective of this article was to investigate whether patients with diabetes are particularly at risk of pulmonary complications during the perioperative stage of coronary bypass surgery. Methods: The data of 8555 patients who had undergone coronary bypass operations in the years between 1996 and 2004 were analyzed. Depending on their diagnosis on admission and their fasting plasma glucose levels, these patients were classified as having "no diabetes'' (fasting plasma glucose level < 126 mg/dL), "undiagnosed diabetes'' (glucose level >= 126 mg/dL), "oral therapy diabetes,'' or "insulin-treated diabetes.'' The 3 diabetic groups were compared with the nondiabetic group in terms of the preoperative and postoperative characteristics. Results: The reintubation rate among patients with undiagnosed diabetes (4.6%) and among those with insulin-treated diabetes (4.5%) was significantly higher than that of nondiabetic patients (1.8%; P < .01). The proportion of patients who required respiration for periods longer than 1 day was also significantly higher among patients with undiagnosed diabetes (9.9%) and those with insulin-treated diabetes (8.6%) than among the nondiabetic patients (4.8%; P < .01). The regression models show that unidentified diabetes and insulin-treated diabetes constitute independent risk factors for perioperative pulmonary complications. Conclusions: Patients with undiagnosed and insulin-treated diabetes have a higher risk of having pulmonary complications in the perioperative course of coronary bypass operations than do nondiabetic patients. These results may be explained if one considers the lung as another target organ of the diabetic disease.