Background: Diabetes mellitus (DM) is known to be associated with atherosclerosis and endothelial dysfunction. However, whether the duration of DM can be associated with coronary artery spasm (CAS) with the intracoronary acetylcholine (Ach) provocation test is not clear. Methods: A total 71 consecutive patients (pts, 39 men; mean age 57.6짹12.4 years) without significant coronary artery disease who underwent the Ach provocation test by injecting incremental doses of 20, 50, 100 ug into the left coronary artery were enrolled between November 2004 and March 2009. Siginificant CAS was defined as focal or diffuse severe transient luminal narrowing (>70%) with/without chest pain or ST-T change on ECG. The Ach provocation test results and its associated parameters were compared between the diabetic pts with history of ��� 10 years group (n= 21 pts) and < 10 years (n=50 pts). Results The clinical and angiographic characteristics were similar between two groups. Basal diffuse spasm at baseline coronary angiography tended to be higher and the incidence of myocardial bridge (MB) was more common in the DM < 10 years group. However, after Ach injection, the rate of positive provocation test result and associated clinical and angiographic parameters were not different between the two groups (Table).Conclusion: In our study, pts with over 10 years of DM duration did not show any significant impact on the incidence of Ach induced CAS, associated clinical and angiographic parameters compared with those of pts with less than 10 years of DM duration.