Post-Heart Transplant Diabetes Mellitus: Incidence, Prevalence and Outcomes

Purpose De novo diabetes mellitus (DM) is a common complication of solid organ transplantation. However, studies about post-transplant DM (PTDM) following heart transplantation (HT) are scarce. This study aims to compare baseline characteristics and clinical outcomes between patients who developed PTDM and those who did not as well as investigate the incidence and prevalence of PTDM following HT. Methods 148 consecutive patients undergoing HT between 4/2014 and 12/2018 were enrolled to this retrospective study. PTDM diagnosis was made based on a HbA1c ≥6.5%, fasting blood glucose ≥ 126mg/dL or use of insulin or oral hypoglycemic agents. Results Of the 148 patients, 57 (39%) had no DM, 37 (25%) had DM prior to HT, and 54 (36%) developed PTDM. Among the patients without DM at the time of HT, cumulative incidence of PTDM was 37% at discharge, 46% at 6 months, and 48% at 1 year post-HT. The prevalence of PTDM at 6 months post-HT was 44% and decreased to 36%, 26%, and 17% at 1, 2, and 3 years, respectively (Figure 1A). PTDM patients had a significantly higher pre-HT HbA1c compared to those without DM (5.8 (5.6, 6.0) vs 5.5 (5.3, 5.9)%; p=0.017). There was no difference in the dose of immunosuppressive medications between the groups. PTDM patients had a higher rate of infection requiring hospitalization compared to patients with no DM post-HT (80% vs 61%; p=0.036). Infection free survival was significantly lower in the PTDM group at 2 years (16% vs 35%; p=0.046) (Figure 1B). Overall survival (96% vs 96% at 2 years; p=0.986), rejection-free survival (46% vs 51% at 2 years; p=0.410), rate of cardiac allograft vasculopathy (33% vs 22%; p=0.267), kidney function and number of hospitalizations were similar between the PTDM and no DM groups. Conclusion The incidence of PTDM after HT was high but prevalence decreased after 6 months. Patients with PTDM had increased pre-HT HbA1c and higher post-HT rates of infection compared to patients without DM. Further studies are needed to determine the clinical impact of PTDM.