Abstract

Objective: The β-score is a highly regarded approach to the assessment of transplant functionality. Our aim was to develop an index of β-cell function that hinges on the pillars of β-score (daily insulin requirement and HbA_1c), has a straightforward physiological interpretation, and does not require the execution of an insulin-stimulation test.

Research Design And Methods: The new index is denoted TEF (Transplant Estimated Function) and is obtained from daily insulin requirement and HbA_1c. TEF estimates the amount of insulin secreted daily and can be normalized to the number of transplanted islets, thus permitting evaluation of the cost-effectiveness of the transplant. TEF was compared with the area under the curve (AUC) of C-peptide concentration over 24 hrs, as well as the acute insulin response to intravenous glucose (AIR_glu) and arginine (AIR_arg). The association between TEF and β-score was also investigated.

Results: TEF correlation with. 24-hrs-AUC(C-pep) was r=0.73 (p<0.005), whereas β-score vs. 24-hrs AUC(C-pep) was r=0.33 (p=NS). TEF correlation with AIR_glu was r=0.59 (p<0.001) and close to β-score vs. AIR_glu (r=0.65, p<0.001). TEF correlation with AIR_arg was r=0.33 (p<0.005) and similar to β-score vs. AIR_arg (r=0.34, p<0.005). TEF and β-score were correlated well (r=0.69, p<0.0001) and showed similar time profiles.

Conclusions: TEF estimates daily insulin secretion, it is simpler than β-score, and its performance against reference indices of β-cell secretion is in line with that exhibited by β-score. TEF can be normalized to the number of transplanted islets, and thereby provide a benchmarking tool to evaluate the cost-effectiveness of the transplant.