Background: There has been limited data regarding impact of diabetes mellitus (DM) on coronary artery endothelial dysfunction is not clarified yet. We compared the severity of acetylcholine (Ach)-induced coronary artery endothelial dysfunction between DM and non-DM patients and according to the glycemic control level. Methods: This study consisted of 1,083 patients (pts, Male 539, Age 56.46짹12.23 years) without significant coronary artery disease underwent Ach provocation test by injecting incremental doses of 20, 50 and 100 g to left coronary artery. Coronary artery endothelial dysfunction severity was defined as mild (<50%), moderate (50– 0%) or severe transient luminal narrowing (>70%) regardless of chest pain or ST-T change of EKG. Impact of presence of DM and HbA1c on the coronary endothelial dysfunction severity was analyzed. Results: Conventional risk factors of coronary atherosclerosis were not different between the groups. DM patients did not show any difference in Ach induced mild, moderate, or severe endothelial dysfunction distribution compared to non-DM patients (Table 1). This finding was constant when insulin/OHA treated group and diet therapy group was compared (Table 2). Also, HbA1c level did not reveal any difference in distribution between any of the pre-defined endothelial dysfunction severity (Table 3). Conclusion: DM patients did not show any difference in endothelial dysfunction distribution compared to non-DM patients.

Transient luminal narrowing by QCA	DM (n=122)	Non-DM (n=961)	p-value
mild (< 50%) moderate (50-70%) severe (> 70%)	77 (63.1%) 65 (53.0%) 27 (22.1%)	559 (58.2%) 509 (53.5%) 276 (28.7%)	0.172 0.513 0.076
HbA1c	< 7 (n=390)	7 - 9 (n=40)	> 9 (n=13)	P-value
mild (< 50%) moderate (50-70%) severe (> 70%)	247 (63.3%) 226 (57.9%) 123 (31.5%)	25 (62.5%) 22 (55.0%) 25 (23.1%)	9 (69.2%) 7 (53.8%) 4 (30.8%)	0.903 0.903 0.696