Objective To investigate the coronary CT imaging features of patients with coronary heart disease and coronary artery disease complicated with type 2 diabetes mellitus. Methods The clinical data of 88 patients diagnosed with coronary heart disease who were treated in our hospital between May 2012 and May 2015 were analyzed retrospectively. According to the status of being complicated with type 2 diabetes mellitus, the patients were divided into diabetes group (n=32) and non-diabetes group (n=56). The two groups of subjects were examined by 128 speed spiral CT coronary angiography. The number of diseased coronary arteries, distribution of coronary artery lesions and characteristics of calcified lesions were compared. Results In 32 patients in diabetes group, 96 diseased blood vessels were detected in the main blood vessel segments of left/right coronary artery, and 124 diseased blood vessels were detected in 56 patients in the non-diabetic group. There were no significant differences in the rate of double diseased branches of coronary arteries, rate of diffuse lesions and the distribution of diseased coronary arteries between the two groups (P>0.05). The rates of multi-vessel lesions and calcified plaques in the diabetic group (46.9%, 60.4%) were significantly higher than those in the non-diabetic group (17.9%, 20.2%) (P<0.05). Conclusion Most coronary CT images of patients with coronary heart disease complicated with type 2 diabetes mellitus show calcified plaque and multi-vessel lesions, which needs clinical attention.