Supplementary Material for: Inflammation on the waiting list is a risk factor for new-onset prediabetes and post-transplant diabetes mellitus: a prospective study.

Introduction: Inflammation is a risk factor for diabetes in the general population. The role of inflammation in prediabetes or post-transplant diabetes (PTDM) is not clear. We evaluated the association between inflammatory markers in patients on the waiting list for renal transplantation and the onset of prediabetes and PTDM 12 months after transplantation. Methods: This is a post-hoc analysis of a prospective study, that included non-diabetic patients on the waiting list for kidney transplantation who underwent an oral glucose tolerance test (OGTT) and were followed up to 12 months after transplantation. At this time, those patients without PTDM underwent another OGTT. At pretransplant five cytokines: TNFα, IL6, IL1β, CRP, MCP1 were determined. The association between inflammation and prediabetes/PTDM was evaluated using multiple regression models. Results: 110 patients on the waiting list were enroled: 74 had normal glucose metabolism and 36 had prediabetes or occult diabetes. At 12 months, 53 patients had normal glucose metabolism, 25 prediabetes and 32 PTDM. In multiple regression analysis, pre-transplant inflammation was not a risk factor for prediabetes or PTDM. This was attributed to the high interrelation between obesity, prediabetes and inflammation: about 75% of the cases had these conditions. In a sub-analysis we analysed only patients without prediabetes and occult diabetes on the waiting list and found that TNFα levels and BMI at pre-transplant were independently associated with the onset of prediabetes or PTDM one year after transplantation. Conclusions: Pre-transplant inflammation and BMI are risk factors for prediabetes and PTDM in patients without glucose metabolism alterations.