Fasting parameters for estimation of stimulated β cell function in islet transplant recipients with or without basal insulin treatment

In order to assess β cell secretory capacity after islet transplantation, standardized mixed meal stimulation tests are often used. But these tests are cumbersome and the effect of exogenous insulin on the test results is unclear. The aim of our study was to determine to what extent fasting glycemic indices can estimate stimulated β cell function in islet transplant recipients with and without basal insulin. In total 100 mixed meal stimulation tests, including 31 with concurrent basal insulin treatment, were performed in 36 islet transplant recipients. In a multivariate model, fasting C‐peptide and fasting glucose together estimated peak C‐peptide with R 2 = .87 and area under the curve (AUC) C‐peptide with a R 2 = .93. There was a larger increase of glucose during tests in which exogenous insulin was used (+7.9 vs +5.3 mmol/L, P
Fasting C‐peptide and glucose can accurately estimate stimulated β cell function during a mixed meal tolerance test in islet transplant recipients, irrespective of concurrent basal insulin use.