Performance of HbA1c and Fasting Plasma Glucose in Screening for Diabetes in Patients Undergoing Coronary Angiography

OBJECTIVE The performance of glycated hemoglobin (HbA1c) and fasting plasma glucose (FPG) was compared in screening for diabetes by an oral glucose tolerance test (OGTT) in patients undergoing coronary angiography (CAG). RESEARCH DESIGN AND METHODS Patients without known diabetes admitted for CAG were eligible. OGTT and HbA1c were assessed 2-4 weeks after hospital discharge. The performance of HbA1c and FPG was evaluated by using receiver operating characteristic (ROC) analysis. RESULTS Diabetes was diagnosed in 83 of 400 patients (20.8%). The area under the ROC curve was higher for FPG than for HbA1c (0.81 vs. 0.73, P = 0.032). We proposed a screening algorithm and validated it in another 170 patients. Overall, this algorithm reduced the number of OGTTs by 71.4% (sensitivity 74.4%, specificity 100%). CONCLUSIONS FPG performed better than HbA1c in screening for diabetes in patients undergoing CAG. A screening algorithm might help to reduce the number of OGTTs.