Prevalence and risks of undiagnosed diabetes mellitus in patients undergoing coronary artery bypass grafting

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 >= 126 mg/dL), or as nondiabetics ( FPG >= 126 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 >= 126 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%; P < 0.01) and reintubation (2.1% versus 5.0% versus 3.5%; P < 0.01) and often showed a longer period of ventilation > 1 day (5.6% versus 10.5% versus 7.4%; P < 0.01). Perioperative mortality rate was highest in this group (0.9% versus 2.4% versus 1.4%; P < 0.01). 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.