Objectives: Diabetics with normal myocardial perfusion imaging (MPI) have a high incidence of adverse cardiac events compared to non-diabetics with normal MPI. However, little is known about the differences in characteristics of coronary atherosclerosis in these patients. This study sought to compare coronary atherosclerosis characteristics in asymptomatic diabetics (ASx-DM) with normal and abnormal MPI, to high risk asymptomatic non-diabetic patients (ASx-nonDM). Methods: ASx-DM with two or more cardiac risk factors (n=72, male 58%) underwent coronary CT angiography (CTA, 64-sliced MDCT) and MPI using technetium-99m sestamibi SPECT. High risk ASx-nonDM, according to NCEP guideline, who had undergone only CTA as part of a routine health screening were selected for comparison. MPI was considered abnormal if there were reversible and/or fixed perfusion defects. Presence and type of atherosclerotic plaque, and significant stenosis (��� 50% diameter stenosis) were determined for each coronary segment on CTA. Results: ASx-DM with normal MPI (n=57) had similar duration of diabetes, glucose control, hypertension, hypercholesterolemia, smoking, and family history of coronary heart disease compared to ASx-DM with abnormal MPI (n=15). ASx-DM with normal MPI had similar incidence of atherosclerotic plaque (78.9% vs 80.0%), non-calcified plaque (24.6% vs 26.7%), significant stenosis (15.8% vs 26.7%) and high coronary artery calcium score (CACS > 100) (56.1% vs 46.7%) compared to ASx-DM with abnormal MPI (all, p>0.05). Compared to ASx-nonDM with high risk factors, ASx-DM with normal MPI had a higher incidence of atherosclerotic plaque (78.9% vs 43.8%, p=0.006) and high CACS (56.1% vs 25.0%, p=0.028), but similar incidence of non-calcified plaque and significant stenosis (24.6% vs 18.8%; 15.8% vs 12.5%, all p>0.05). Conclusion: ASx-DM with normal MPI had increased incidence of atherosclerotic plaque compared to high risk ASx-nonDM. Furthermore, ASx-DM with normal MPI showed similar characteristics of coronary atherosclerosis on CTA compared to ASx-DM with abnormal MPI. Refining risk stratification in ASx-DM using CTA and MPI may provide complementary information on future cardiac events.