The goal of this study was to compare the coronary atherosclerotic burden in patients with and without type-2 diabetes by using CT coronary angiography (CTCA). A total of 206 diabetic (mean age 67 +/- A 11 years; male: 136) and 523 non-diabetic patients (mean age 62 +/- A 13 years; male: 323) without history of coronary artery disease (CAD) underwent CTCA. The per-patient number of diseased coronary segments was determined, and each diseased segment was classified as showing obstructive lesion (luminal narrowing > 50 %) or not. Coronary angiography was then performed to confirm diagnosis. Diabetics showed a higher rate of abnormal CAD (76 vs. 53 % of patients; p < 0.0001) and fewer normal coronary arteries (24 vs. 47 %; p < 0.0001) compared with non-diabetics. Multi-vessel disease was seen more frequently in patients with diabetes than in patients without diabetes [15 % (n = 22) vs. 7 % (n = 62), respectively; p = 0.0004]. The per-patient number of segments with plaque (4.5 vs. 2.0, respectively; p < 0.0001) and the number of segments with obstructive disease (0.9 vs. 0.5, respectively; p = 0.0001) were higher for diabetic patients than for non-diabetic patients. Diabetes was associated with higher coronary plaque burden.