Assessing the risk of post-transplantation diabetes mellitus with an oral glucose tolerance test

This Practice Point commentary discusses the findings of a prospective study by Kuypers et al. that was designed to determine the best clinical diagnostic tool for identifying patients at risk of developing post-transplantation diabetes mellitus (PTDM) following renal transplantation. Fasting plasma glucose (FPG) levels on the day of transplantation and FPG levels and an oral glucose tolerance test (OGTT) at 5 days after transplantation were evaluated in de novo renal transplant recipients. The predictive values of these tests were assessed alongside other known risk factors for PTDM. A normal (vs diabetic) OGTT on day 5 was associated with a significantly reduced risk for PTDM (odds ratio 0.03; P = 0.0002). A similar reduction in the risk of PTDM was conferred by normal FPG levels on day 5 (odds ratio 0.06; P<0.0001). While the OGTT or FPG test at 5 days after transplantation might prove to be useful predictive diagnostic tools for the development of PTDM, studies that incorporate baseline evaluation of pre-existing glucose metabolic disorders are needed.