Objective To determine the CT angiographic characteristics of coronary artery of diabetic patients in different age groups and to discuss the appropriate time for them to undergo coronary computed tomography angiography(CCTA). Methods A retrospective analysis was performed on the coronary CT angiographic characteristics of 1876 diabetic patients suspected of coronary heart disease (CHD). These patients were divided into＜60 years group (878 cases) and≥60 years group(998 cases). The coronary stenosis and calcification score were compared between the two age groups after stratification by hypertension, dyslipidemia, obesity and smoking. Results There were significant differences between the two groups in the prevalence of coronary stenosis (32.11% vs 24.39%, P＜0.05) and the prevalence of multivessel lesions (23.25% vs 14.01%, P＜0.05). After stratification by obesity, smoking, and dyslipidemia, the statistical analysis showed that there were more patients who had severe or/and moderate coronary stenosis, multi-vessel lesions and higher calcium score in≥60 years group than in＜60 years group(P＜0.05). Conclusions For diabetic patients with multiple coronary risk factors and aged≥60 years, early screening for coronary artery disease is recommended. CCTA is a simple and noninvasive method for this task.