BACKGROUND AND OBJECTIVES: Advanced glycation end-products (AGEs) contribute to the development of atherosclerosis. We investigated whether serum AGEs are related to the presence or severity of coronary artery disease (CAD), and explored the association between serum AGEs and arterial stiffness according to diabetes status in patients suspected of having CAD. SUBJECTS AND METHODS: The measurement of serum AGEs and brachial-ankle pulse wave velocity (baPWV) were performed in 145 consecutive patients (63+/-9 years, 58% men) who received a coronary angiogram for evaluation of CAD. RESULTS: Forty-four diabetics and 101 non-diabetics were classified into three subgroups based on the number of diseased vessels with obstructive CAD: 0, 1, and 2 or more vessel diseases (VDs). Serum AGEs were significantly higher in diabetics with obstructive CAD than in those without obstructive CAD (2.16+/-0.29 vs. 1.85+/-0.29 mU/mL, p=0.010) and were significantly correlated with the number of VDs only in diabetics (r=0.504, p<0.001). Serum AGEs were not significantly correlated with baPWV in diabetics or non-diabetics. In receiver operating characteristics analysis, the cut-off value of serum AGEs as a predictor of obstructive CAD was 1.98 mU/mL, with 64% sensitivity and 63% specificity in diabetics. In multiple regression analysis, serum AGEs independently predicted obstructive CAD and were associated with the number of VDs in diabetics. CONCLUSION: Serum AGEs independently predict obstructive CAD and the severity of coronary atherosclerosis irrespective of arterial stiffness only in diabetics. Evaluation of PWV and serum AGEs together may be more effective to identify the risk of CAD in diabetic individuals.