We performed an observational analysis of a prospective cohort of immunocompetent hospitalized adults with community-acquired pneumonia (CAP) to determine the epidemiology, clinical features, and outcomes of pneumonia in patients with diabetes mellitus (DM). We also analyzed the risk factors for mortality and the impact of statins and other cardiovascular drugs on outcomes. Of 2407 CAP episodes, 516 (21.4%) occurred in patients with DM; 483 (97%) had type 2 diabetes, 197 (40%) were on insulin treatment, and 119 (23.9%) had end-organ damage related to DM. Patients with DM had different clinical features compared to the other patients. They were less likely to have acute onset, cough, purulent sputum, and pleural chest pain. No differences in etiology were found between study groups. Patients with DM had more inhospital acute metabolic complications, although the case-fatality rate was similar between the groups. Independent risk factors for mortality in patients with DM were advanced age, bacteremia, septic shock, and gram-negative pneumonia. Patients with end-organ damage related to DM had more inhospital cardiac events and a higher early case-fatality rate than did the overall population. The use of statins and other cardiovascular drugs was not associated with better CAP outcomes in patients with DM. In conclusion, CAP in patients with DM presents different clinical features compared to the features of patients without DM.