© 2017 American Association of Critical-Care Nurses. Background Findings on outcomes of heart transplant patients who had diabetes mellitus before transplant are conflicting. Objective To compare survival, hospitalization, and complications in heart transplant recipients during the first 3 years after surgery in recipients with or without diabetes mellitus before transplant. Methods Of 347 recipients, 64 were diabetic (35.9% taking insulin; mean age 56 years; 17.2% females; 12.5% minorities) and 283 were not (mean age 51 years; 20.8% females; 15.2% minorities). Outcomes examined were length of survival, number of days hospitalized (including transplant admission), acute graft rejection, infection, cardiac allograft vasculopathy, stroke, cancer, and renal dysfunction. Results Patients with pretransplant diabetes spent significantly more time in the hospital during the first 3 years after transplant than did patients without preexisting diabetes (P = .01). Compared with nondiabetic patients, diabetic patients were hospitalized more often for infections and complications related to the cardiovascular, gastrointestinal, respiratory, renal, hematologic, and neurological systems. The 2 groups did not differ significantly in length of survival or in rates of rejection, infection, cardiac allograft vasculopathy, stroke, cancer, or renal dysfunction. Conclusions Heart transplant recipients with pretransplant diabetes fared just as well as patients without pretransplant diabetes in 7 of the 8 outcomes examined, except for the number of days hospitalized during the first 3 years after heart transplant. This study provides clinically important new information on the greater hospitalization time and the reasons for hospitalization during the first 3 years after heart transplant in patients with pretransplant diabetes.