Obesity as an independent predictor of posttransplant diabetes mellitus

Background. In the general population, there is a clear association between obesity and type 2 diabetes mellitus. However, the evidence of relationship between body mass index (BMI: weight/height²) and the risk of posttransplant diabetes mellitus (PTDM) is inconsistent when studied at a level of single center. The aim of our study was to determine if pretransplant BMI is an independent risk factor for PTDM at our center and to demonstrate the pattern of weight gain in patients who develop PTDM. Methods. This is a retrospective analysis of renal allograft recipients at University of Colorado Hospital. The medical records of patients who received a kidney transplant from January 1998 to March 2001 were screened to identify the cases of PTDM. Controls were matched for immunosuppressive regimen, gender, and type of donor. A total of 18 cases and 36 controls were identified. Results. The incidence of PTDM in our transplant population was 10%. Of these cases, 72% developed PTDM in the first 2 months after transplant, and 38% of them required insulin. On multivariate analysis, BMI was significantly associated with PTDM (adjusted odds ratio 1.22, 95% confidence interval 1.04-1.42) while controlling for number of rejections, age, and other factors. We also noticed that weight gain was significantly lower in patients who developed PTDM after transplantation. Conclusions. We conclude that obesity is an independent predictor of PTDM. The weight gain was significantly poor among patients who developed PTDM. Among all the risk factors for PTDM, obesity is the only modifiable risk factor before transplantation. Obese patients should be treated with a less diabetogenic immunosuppressive regimen and be counseled to lose weight before transplant.