Objective To explore the application of coronary CT angiography (CTA) in assessing the degree of luminal stenosis of coronary intermediate lesions in patients with diabetes. Methods A retrospective analysis was performed in 62 patients with type 2 diabetes mellitus and coronary intermediate lesions diagnosed by coronary angiography (CAG) who were admitted to the hospital from May 2016 to May 2017. All patients were examined by CTA, and the vascular stenosis rate was evaluated. With the stenosis rate measured by CAG as the golden standard, and 50% as the boundary value to judge the degree of vascular stenosis, the sensitivity, specificity and accuracy of CTA were calculated. The consistency of results of CTA and CAG was compared. Results The sensitivity, specificity, positive predictive value, negative predictive value and accuracy rate of CTA in assessing coronary artery stenosis were 90.80%, 88.89%, 79.79%, 95.23% and 89.51%, respectively. There was a good consistency between CTA and CAG in the diagnosis of coronary artery stenosis (Kappa=0.769). Conclusion The specificity, sensitivity, negative predictive value and accuracy of CTA are high in evaluating the severity of luminal stenosis of coronary intermediate lesions. It can be used for detecting the severity of luminal stenosis of coronary intermediate lesions in patients with diabetes.