PURPOSE: Coronary artery calcium scoring (CACS) is widely used to differentiate an asymptomatic individual at high risk from an individual at low risk for diabetes. However, CACS only detect calcified plaque as a surrogate marker of coronary atherosclerosis, and the absence of calcified plaque alone might not be enough to exclude future cardiac events. We, therefore, assessed the relationship between CACS and plaque composition determined by coronary CT angiography (CTA) in asymptomatic diabetes. METHODS: One-hundred seventy-seven asymptomatic type II diabetes (57.3 짹 9.1 years, male 69.5%, duration of DM 5.7 짹 7.2 years) consecutively underwent coronary CT angiography (CTA), using 64 slice multidetector CT. CACS as a whole and presence and type (non-calcified, mixed or calcified) of atherosclerotic plaque, significant stenosis (��� 50% diameter stenosis) for each coronary segment were determined on CTA. RESULTS: Ninety-five (53.7%) patients who had atherosclerotic plaques (2.2 짹 1.3 segments per subjects; range 1 to7) and 16 (9%) patients had significant coronary artery stenosis. 21.6% (45) of plaques were characterized as non-calcified, 30.3% (63) as calcified, and 48.1% (100) as mixed plaques. The mean CACS of the whole patients was 74.1 짹 192.7 [range 0 to 1522], and the distribution of CACS was as follows; 23 (13.7%) patients with CACS > 400, 28 (16.7%) with CACS 100 to 400, and 117 (69.6%) with CACS < 100. Dividing subjects according to CACS, incidence of obstructive lesions, calcified and mixed plaques increased proportional to CACS (all p<0.001). However, incidence of non-calcified plaque was not related CACS (p>0.05), and 48.4% patients with non-calcified plaque have a negligible CACS (<100). CONCLUSIONS: Although current screening method guided by CACS could detect obstructive CAD, calcified and mixed plaques efficiently in asymptomatic diabetes, it is not sufficient to detect non-calcified plaque. Screening of non-calcified plaque by CTA could detect high-risk subjects who are missed in CACS and allow for improved cardiovascular risk management in asymptomatic diabetes.