(1) Background: To analyze the incidence, clinical characteristics, use of procedures, and in-hospital outcomes in patients who developed pneumonia during their hospital admission according to sex and to the presence of type 2 diabetes mellitus (T2DM). (2) Methods: Retrospective cohort study using data from the Spanish National Hospital Discharge Database. Hospital-acquired pneumonia (HAP) was classed as non-ventilator HAP and ventilator-associated pneumonia (VAP). Separate analyses were performed for men and women with and without T2DM. Population subgroups were compared using propensity score matching. (3) Results: HAP was identified in 38,814 patients (24.07% with T2DM). The adjusted incidence of HAP was higher in patients with T2DM (both sexes) (IRR 1.28; 95% CI 1.25–1.31). The incidence of HAP was higher in men with T2DM than in women with T2DM (adjusted-IR 1.47; 95% CI 1.41–1.53). The incidence of HAP among T2DM patients increased over time. In-hospital mortality (IHM) was around 28% irrespective of T2DM status and sex. After adjusting for confounders and sex, VAP was associated to higher IHM among patients with T2DM (OR 2.09; 95% CI 1.7–2.57). (4) Conclusions: T2DM is associated with a higher risk of HAP, whose incidence increased over time. Men with T2DM have an almost 50% higher risk of HAP than women with T2DM. The probability of dying in the hospital was not associated with sex or T2DM.