Influence of Pretransplant and Posttransplant Diabetes on Long-Term Heart Transplant Outcomes

BACKGROUND Diabetes mellitus (DM) is increasingly prevalent among heart transplant candidates, but its long-term prognostic significance remains undefined. The impact of posttransplant DM (PTDM) and insulin-dependent PTDM on outcomes has not been fully characterized. This study evaluated associations of pretransplant DM, PTDM, and insulin-dependent PTDM with long-term outcomes after heart transplantation. MATERIAL AND METHODS Adult heart transplant recipients in the Scientific Registry of Transplant Recipients between December 2005 and December 2020, with no prior transplant, were included. Recipients were stratified by pretransplant DM status, PTDM development, and insulin dependence among PTDM patients. Overall survival (OS) was assessed using Kaplan-Meier analysis, and independent predictors of mortality and PTDM were evaluated using multivariable Cox and logistic regression. RESULTS A total of 30 430 recipients were analyzed, including 8361 with pretransplant DM. Pretransplant DM was associated with worse 10-year OS and independently predicted mortality (HR=1.39, 95% CI: 1.32-1.46; P<0.001). Recipients with pretransplant DM also had higher rates of acute drug-treated rejection, dialysis requirement, drug-treated infection, and infection- or pulmonary-related death. Among 21 121 recipients without pretransplant DM, 3003 developed PTDM. PTDM was independently associated with worse OS (HR=1.14; 95% CI, 1.06-1.22; P=0.001), acute rejection, and infection. Among patients with PTDM, insulin-dependent PTDM conferred greater mortality risk than non-insulin-dependent PTDM (HR=1.58; 95% CI, 1.38-1.80; P<0.001) and was associated with higher rates of rejection, dialysis, infection, and cardiovascular death. CONCLUSIONS Diabetes across the transplant continuum has distinct prognostic implications after heart transplantation. Pretransplant DM and PTDM are independently associated with worse long-term OS, while insulin-dependent PTDM identifies a particularly high-risk subgroup.