Performance of computed tomography versus chest radiography in patients with pulmonary tuberculosis with and without diabetes at a tertiary hospital in Riyadh, Saudi Arabia Yosra M Alkabab,1 Mushira A Enani,2 Nouf Y Indarkiri,3 Scott K Heysell1 1Department of Medicine, Division of Infectious Diseases and International Health, University of Virginia, Charlottesville, VA, USA; 2Department of Infectious Diseases, King Fahad Medical City, 3Department of Family Medicine, Prince Sultan Military Medical City, Riyadh, Saudi Arabia Background: Prior research suggests that diabetes mellitus (DM) is associated with increasing risk for developing cavitary lung disease in patients with pulmonary tuberculosis (TB). Additionally, chest computed tomography (CT) scan may be more sensitive than chest X-ray in detecting cavitary disease in such patients. The aim of this study was to compare the performance of chest CT to chest X-ray in detecting cavitary lung disease and to compare the frequency of cavities between TB patients with DM and without DM.Patients and methods: We conducted a retrospective cohort study at King Fahad Medical City, Riyadh, Saudi Arabia, from January 2004 to December 2015. We included patients aged 18 years and older with a positive sputum culture for Mycobacterium tuberculosis, and their medical charts were reviewed from admission to discharge.Results: Of the 133 patients who met the inclusion criteria, 38 (28.6%) patients were known to have DM and were compared with 95 (71.4%) patients without DM. DM patients with glycated hemoglobin (HbA1c) >6.5% had significantly more cavitary lesions when compared to all patients (with or without DM) with HbA1c <6.4% and/or random blood sugar <200 mg/dL. Furthermore, CT was able to detect lung cavities in 58.8% of the patients who had negative chest X-ray findings for cavities.Conclusion: The presence of lung cavities was significantly associated with the presence of DM and levels of HbA1c in patients with pulmonary TB. CT scan in those with normal radiography increased the detection of cavities. Keywords: diabetes, pulmonary tuberculosis, lung cavities, computed tomography