The aim of this study was to determine the factors affecting the severity of COVID-19 pneumonia in patients with type 2 diabetes using computed tomography severity scores. Computed tomography findings and pneumonia scores of 136 patients with type 2 diabetes and 136 patients without diabetes (n=272) with positive polymerase chain reaction test between January 2020 and January 2021 were compared using the hospital information system. The number of patients with moderate and severe pneumonia was significantly higher in the type 2 diabetes group (p<0.05). Pneumonia scores were significantly higher in type 2 diabetic patients older than 60 years (p<0.05). No significant correlation was found between pneumonia scores and hemoglobin A1c (p=0.865) and fasting blood glucose (p=0.78). No negative effect of hypertension on pneumonia score was observed in diabetic patients. Pneumonia scores of diabetic patients with renal insufficiency were higher than those of diabetic patients aged <60 years (P<0.05). In conclusion, the present study results revealed that the severity of COVID-19 pneumonia in patients with type 2 diabetes is higher than in healthy subjects. However, there was no significant positive correlation between pneumonia severity, hyperglycemia, and hemoglobin A1c levels in patients with type 2 diabetes.