In recent advance in technology, coronary CT angiography makes it more accurately and easier in detecting CAD not only in symptomatic patients but also in asymptomatic population. In asymptomatic population, coronary CT angiography could detect subclinical coronary atherosclerosis with high sensitivity and specificity. However, there is a paucity of information on the role of coronary CT angiography as a screening method in high risk asymptomatic population, i.e. asymptomatic patients with diabetes.