Usefulness of preoperative oral glucose tolerance testing for perioperative risk stratification in patients scheduled for elective vascular surgery

Patients scheduled for major vascular surgery are screened for cardiac risk factors using standardized risk indexes, including diabetes mellitus (DM). Screening in patients without a history of DM includes fasting glucose measurement. However, an oral glucose tolerance test (OGTT) could significantly improve the detection of DM and impaired glucose tolerance (IGT) and the prediction of perioperative cardiac events. In a prospective study, 404 consecutive patients without signs or histories of IGT or DM were included and subjected to OGTT. The primary study end point was the composite of perioperative myocardial ischemia, assessed by 72-hour Holter monitoring using ST-segment analysis and troponin release. The primary end point was noted in 21% of the patients. IGT was diagnosed in 104 patients (25.7%), and new-onset DM was detected in 43 patients (10.6%). The OGTT detected 75% of the patients with IGT and 72% of the patients with DM. Preoperative glucose levels significantly predicted the risk for perioperative cardiac ischemia; odds ratios for DM and IGT were, respectively, 3.2 (95% confidence interval 1.3 to 8.1) and 1.4 (95% confidence interval 0.7 to 3.0). In conclusion, the prevalence of undiagnosed IGT and DM is high in vascular patients and is associated with perioperative myocardial ischemia. Therefore, an OGTT should be considered for all patients who undergo elective vascular surgery.