Background: Precise, yet logistically feasible evaluation of beta-cell function is extremely important after total pancreatectomy with islet autotransplantation (TP-IAT). We investigated the utility and possible limitations of indices using only a single fasting blood glucose and C-peptide levels: The Secretory Unit of Islet Transplant Objects (SUITO), transplant estimated function (TEF), homeostasis model assessment (HOMA)2-B%, C-peptide/glucose ratio (CP/G), C-peptide/glucose creatinine ratio (CP/GCr) and BETA-2 score  as we did it previously for islet allografts.
Methods: Laboratory values from clinical evaluations in patients submitted to TP-IAT were analyzed at different times post TP-IAT. The six surrogate indices were compared against 90-min serum glucose and peak glucose in mixed meal tolerance test (MMTT), beta-score and a modified version of the Igls score which we propose for the assessment of islet function in the setting of IAT. Accurate estimates of the areas under receiver operating characteristic curves (AUROC) were obtained to see which tool would best predict insulin independence.
Results: We analyzed values from 32 MMTTs in 15 patients after TP-IAT due to chronic pancreatitis and intractable pain (8 women and 7 men).  Mean age was 39 ± 12.8 years and follow up 3 years. Four (27%) patients stopped insulin completely prior to day 75, maintaining A1c of 5.8% (5.2-6.3). Seven of 13 patients (54%) did not require insulin support at 1 year with A1c 6.0% (5.5-6.8). The remaining 6 patients were taking insulin with A1c 6.7% (5.5-8.4). All 3 patients who completed 2-year follow-up are currently off insulin with A1c of 5.8%. SUITO, CP/G, TEF and BETA-2 were well correlated with MMTT 90-min and peak glucose and beta-score (r in the range 0.5–0.72), whereas CP/GCr and HOMA-2B showed a modest performance (r = 0.3). Upon ROC analysis all surrogate indices reliably identified insulin independence and optimal/good vs. marginal islet function in modified Igls score, while BETA-2 and TEF showed the best performance with AUROC 0.85-0.99 (95% confidence interval 0.7-1.0, p<0.001). BETA-2 ≥ 9.11 differentiated between good and marginal islet function according to our modification of Igls score for IAT. BETA-2 ≥ 16.45 detected insulin independence. This value was higher than previously reported for alloislets transplant recipients.
Conclusions: Using a single fasting blood sample, SUITO, CP/G, TEF and BETA-2 scores offer a simple and valid alternative tool allowing frequent assessments of graft function in patients undergoing TP-IAT.