Assessment of beta-cell function and insulin secretion in subjects that underwent renal transplantation

In this study we aimed to assess the performance of various indices of beta-cell function derived from oral glucose tolerance test (OGTT) in subjects that underwent renal transplantation. Impaired insulin secretion seems in fact central for development of new onset diabetes after transplantation, but its assessment has not been systematically evaluated. Twenty subjects underwent a 75 g 2h-OGTT for measurement of glucose, insulin, C-peptide. OGTT indices of beta-cell function were either derived by mathematical modeling (yielding the reference index: glucose sensitivity) or were empirical: insulinogenic index (IGI), IGI derived indices, whole shape C-peptide (WHOSH-CP). Indices of beta cell function, showed significant correlation with glucose sensitivity (R2=0.40-0.86, all P<0.003). The majority of beta-cell function indices provided comparable results also when subjects were divided into subgroups according to sex, age, body mass index, mean glycemia. In conclusion, in transplanted subjects OGTT empirical indices are typically acceptable for the estimation of beta-cell function