Abstract: Objective: To analyze the clinical and CT features of elderly patients with type 2 diabetes mellitus complicated with pulmonary infection. Methods: A total of 150 elderly patients with type 2 diabetes mellitus and pulmonary infection treated in our hospital from May 2019 to May 2021 were analyzed retrospectively. Results: The positive rate of pathogenic bacteria was 90% (135/150), most of which were gram negative. The CT manifestations of 150 patients were mainly lobular pneumonia, lobar pneumonia, pulmonary tuberculosis, pulmonary abscess and fungal infection, and the number of the cases were 62, 41, 31, 9, 7 respectively;Lobular pneumonia and pulmonary tuberculosis were mainly distributed in multiple lobes while lobar pneumonia and pulmonary fungal infection were mainly distributed in single lobe; Among the 150 ceses, there were 101 cases with good blood glucose control and 49 cases with poor blood glucose control. We compared the healing efficacy betwwen the two groups, and found that the difference was statistically significant. Conclusion: Elderly patients with type 2 diabetes are easily associated with pulmonary infection. CT can accurately analyze the pathological changes in the lung.