Risk Factors and Clinical Implications of Post-Transplant Diabetes Mellitus: Role of Vitamin D Status

Background: Post-transplant diabetes mellitus (PTDM) is a significant metabolic complication affecting kidney transplant recipients (KTx), contributing to increased cardiovascular morbidity, infections, graft dysfunction, and decreased survival. Understanding the risk factors associated with PTDM is essential for prevention and improved management. The aim of this study is to evaluate the association between vitamin D levels and the development of in PTDM KTx. Methods: This retrospective cohort study included 106 KTx followed between 2005 and 2020 (median follow-up 8.1 years). Data on demographic characteristics, transplantation details, immunosuppressive regimens, dialysis history, vitamin D status, and clinical outcomes were analyzed. Logistic regression analysis identified independent predictors of PTDM. Results: Post-transplant diabetes mellitus incidence was 25.5%. Age over 50 years (odds ratio (OR) = 1.83, 95% CI: 1.25-2.72, P = .036), retransplantation (OR = 2.16, 95% CI: 1.32-2.88, P = .009), and vitamin D deficiency (<20 ng/mL) (OR = 1.70; 95% CI: 1.25- 2.72; P = .029) were independently associated with PTDM development. Continuous vitamin D levels, analyzed per 5 ng/mL decrease, were also significantly associated with PTDM (OR = 1.53, 95% CI: 1.09-2.25; P = .028). Receiver operating characteristic analysis identified serum vitamin D as the strongest predictor (AUC 0.761; sensitivity 0.72; specificity 0.68). The PTDM was associated with higher rejection episodes (37.0% vs. 15.2%, P = .004), increased mortality (18.5% vs. 7.5%, P = .012), and a trend toward higher allograft loss (25.9% vs. 12.7%, P = .058). Kaplan–Meier curves demonstrated consistently lower patient and graft survival in the PTDM group, although differences were not statistically significant after multivariate adjustment. Conclusion: The PTDM occurred in one-quarter of KTx and was independently predicted by older age, retransplantation, and vitamin D deficiency.   Cite this article as: Akgül A, Demir ME, Oguz EG, Aylı MD. Risk factors and clinical implications of post-transplant diabetes mellitus: role of vitamin D status . Turk J Nephrol. Published online February 23, 2026. doi:10.5152/turkjnephrol.2026.251015.