Background-Numerous studies have shown that diabetes mellitus (DM) is not identified and, consequently, inadequately treated in a substantial proportion of the patients in the general population. We know very little about the extent and the consequences of undiagnosed diabetes in the risk group of patients with coronary heart diseases. The objective of this study was therefore to determine the prevalence and the risks of undiagnosed DM among patients with coronary artery bypass. Methods and Results-The data of 7310 patients who have undergone coronary bypass operations between 1996 and 2003 were analyzed. Depending on their diagnosis on admission and their fasting plasma glucose (FPG) level, these patients were classified as known diabetics, undiagnosed diabetics (FPG Ն126 mg/dL), or as nondiabetics (FPG Ͻ126 mg/dL) and were compared in terms of their preoperative, intraoperative, and postoperative characteristics. Among the patients with coronary bypass that we examined, we found a prevalence of diagnosed diabetics of 29.6%. The prevalence of patients with undiagnosed DM (FPG Ն126 mg/dL) was 5.2%. In comparison with the other groups (non-DM versus undiagnosed DM versus known DM), the undiagnosed diabetics more frequently required resuscitation (1.7% versus 4.2% versus 1.5%; PϽ0.01) and reintubation (2.1% versus 5.0% versus 3.5%; PϽ0.01) and often showed a longer period of ventilation Ͼ1 day (5.6% versus 10.5% versus 7.4%; PϽ0.01). Perioperative mortality rate was highest in this group (0.9% versus 2.4% versus 1.4%; PϽ0.01). Conclusions-This study is the first to publish the prevalence of undiagnosed diabetes mellitus in cardiac surgery. During the perioperative and postoperative courses, these patients displayed a substantially higher morbidity and mortality rate.

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.

A steady increase in the numbers of diabetic patients in coronary surgery has been recorded over the last years. The causes for these rises are seen mainly in the general demographic development in the western industrialized nations, the epidemic progress and wide spread of diabetes mellitus, and changes in assignment behavior. In the following, the specific risk profile of diabetic coronary patients in heart surgery and tried and tested treatment concepts for this particularly challenging group of patients with reference to most recent study results will be presented. Particularly the peculiarities of coronary heart disease in diabetic patients, the choice of the revascularization method, different operative strategies for diabetic patients with coronary heart disease, and challenges faced at the cardiac surgery intensive care unit are discussed in detail.

Advances in percutaneous coronary revascularization have meant that, increasingly, patients with multivessel diseases are initially treated with the methods of interventional cardiology. Ongoing studies involving new stent coatings and optimized anti-thrombotic therapies could help to lower future restenosis rates and improve the success rate of stenting. Thrombocyte glycoprotein IIb/IIIa receptor blockers have already been shown to reduce the rate of acute PTCA complications in high-risk patients and could have a sustained impact on the long-term prognoses for PTCA patients. However, for diabetic patients with coronary multivessel diseases, coronary artery bypass grafting using arterial grafts as the initial revascularization method must be given preference over other therapy methods. Consequently, this group of patients is bound to grow in importance in cardiac surgery. The advances made in percutaneous coronary revascularization and in coronary surgery call for further prospective, controlled, randomized clinical studies in order to establish the best possible treatment strategy for patients with diabetes. It should be noted, however, that the therapeutic effect of myocardial revascularization is generally limited to individual coronary-arterial segments, whereas the pathological process of atherosclerosis is rather diffuse. The surgical strategy should therefore be seen as part of an overall strategy which encompasses other forms of treatment (e.g. intensive efforts to improve control of blood glucose level, blood pressure, and cholesterol level) in order to arrest the general progression of the disease and to reduce the risk of myocardial infarction and death.

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