The objective of this paper was to investigate the clinical features and pulmonary CT imaging features of COVID-19 patients with diabetes mellitus. From January 16, 2020 to March 28, 2020, among the 568 cases of COVID-19 patients diagnosed in Xiaogan Central Hospital, 64 cases of COVID-19 patients with diabetes were selected as the diabetic group, and 64 cases of COVID-19 patients with age and gender matching without diabetes were selected as the non-diabetic group, and their clinical data and pulmonary CT characteristics were retrospectively analysed. Compared with the non-diabetic group, the proportion of patients in the diabetic group with chronic underlying disease was higher, and they were in more a serious condition at admission. Inflammation index and characteristics of glycolipid metabolism results showed that COVID-19 patients with diabetes mellitus were more likely to have elevated inflammatory markers and hypercoagulability, accompanied by hypoproteinaemia and glucose and lipid metabolism disorders. Treatment and clinic outcome results showed that the time of nucleic acid turning negative in the diabetic group was significantly longer than that in the non-diabetic group. Radiological data showed that COVID-19 combined with diabetes prolonged the time of detoxification in patients. COVID-19 patients with diabetes mellitus and chronic hypertension are associated with increased inflammatory markers and disorders of glucose and lipid metabolism. These patients tend to develop serious diseases, especially the rapid progression of CT lesions in the lungs of patients with a wide range ofinvolvement, and prolonged absorption and detoxification time.