Oral Glucose Tolerance Test as a Risk Marker for Developing Post-Transplant Diabetes Mellitus

The incidence of post-transplant diabetes mellitus (PTDM) can reach 30% during the first 6 months after kidney transplantation (KT), increasing the risk of graft failure and mortality. There is no well-established biomarker for predicting PTDM occurrence. This study evaluated the association between the abnormal 2-hour oral glucose tolerance test (OGTT) and the PTDM incidence.

A retrospective single-center study, including adult kidney transplant recipients from deceased donors, was performed between March 2021 and June 2022.

age <18 years; pretransplant diabetes mellitus (DM); death with a functioning graft; loss of follow-up and/or graft failure before 6 months post-transplant. The results of pretransplant OGTT, fasting (FPG), and afternoon plasma glucose levels at hospitalization and FPG in the first, second, and third months post-transplant were evaluated. For analysis, patients were grouped according to the PTDM diagnosis: PTDM and non-PTDM.

From 164 KT performed in the period, 50 (30%) were included, most male (n = 34, 68%), with a mean age of 48.3 ± 12.5 years. Nine patients (18%) developed PTDM, 44% between 3 and 6 months. General characteristics and immunosuppressive therapy were similar between the groups. The mean FPG in the pretransplant OGTT was significantly higher in the PTDM group compared with the non-PTDM group (85.7 ± 7.9 vs 79.1 ± 8.2, P = .03). The number of patients classified as impaired glucose tolerance (IGT) on the pre-transplant OGTT was significantly higher in the PTDM group.

IGT in the pretransplant OGTT was associated with PTDM cases in kidney transplant recipients without a previous diagnosis of DM.