C-Peptide and Glucose Values in the Peritransplant Period After Intraportal Islet Infusions in Type 1 Diabetes R.N. Faradji, K. Monroy, P. Cure, T. Froud, D. Baidal, A. Pileggi, S. Messinger, C. Ricordi, and R. Alejandro ABSTRACT Background. Successful islet allograft transplantation has been achieved worldwide. This study aimed at evaluating the relationship between peritransplant C-peptide (CP) values and long-term allograft function. Methods. We measured CP-to-glucose ratio (CPGR) in intraportal samples pre- and postinfusion, and in peripheral circulation at baseline pretransplant and at 1, 3, 6, 12, 72 hours, 1 week, and 15 and 30 days after first and second infusion in 13 islet allograft recipients. Peritransplant treatment included intravenous (IV) 5% dextrose in saline in all patients. We compared portal CPGR to insulin reduction (%) at 30 days after each infusion, and at 1 year after second infusion. Results. CPGR peaked between the immediate postinfusion and 3 hours and decreased at 12 hours. At 1 week, CPGR was 0.76  0.45 and 1.44  0.37 after first and second infusion, respectively. CPGR at 30 days after second infusion doubled compared to first infusion (P  .001). There was no correlation between peak CPGR and insulin reduction percent at any time point. One patient experienced hypoglycemia (47 mg/dL) 1 hour after second infusion. Conclusions. There was no relationship between the CP values in the peritransplant period and long-term graft function or success rate. The early peak in the C-peptide levels is indicative of a significant insulin release after each islet infusion. For this reason, it is important to carefully monitor serum glucose levels in the peritransplant period (hourly for the first 6 hours) and to maintain an IV glucose infusion to avoid hypoglycemia. I SLET ALLOGRAFT transplantation can restore -cell function and provide a better physiological glycemic control than exogenous insulin administration, particularly in patients with hypoglycemia unawareness. 1,2 Currently, there is a need to identify a test that can predict engraft- ment and long-term outcomes of islet allografts. C-peptide levels can be measured prior to and after islet transplanta- tion as a mean of quantifying endogenous insulin secretion and to document islet graft function. Production of tissue factor by islet cells may trigger detrimental thrombotic events. Increase in thrombin-antithrombin complex and C-peptide levels in the peritransplant period has been related to islet cell stress and poor outcome. 3,4 The aim of this study was to evaluate the relationship between peri- transplant C-peptide values and long-term allograft func- tion. METHODS In 13 recipients of two consecutive islet allografts, who belonged to the islet-alone protocol and underwent treatment with steroid-free immunosupression, we measured the C-peptide and glucose levels From the Departments of Medicine (R.N.F., R.A.), Surgery (T.F., A.P., C.R.), and Epidemiology (S.M.), Diabetes Research Institute (R.N.F., K.M., P.C., T.F., D.B., A.P., S.M., S.R., R.A.), University of Miami Miller School of Medicine, Miami, Florida, USA. This study was supported by grants from the National Insti- tutes of Health/NIDDK (R01 DK52802), NCRR (GCRC- MO1RR16587; U42RR016603), JDRFI (4-2004-361), State of Florida and Diabetes Research Institute Foundation. Address reprint requests to Rodolfo Alejandro, MD, Diabetes Research Institute, 1450 NW 10 Avenue (R-134), Miami, FL 33136 USA. E-mail: ralejand@med.miami.edu © 2005 by Elsevier Inc. All rights reserved. 0041-1345/05/$–see front matter 360 Park Avenue South, New York, NY 10010-1710 doi:10.1016/j.transproceed.2005.09.090 Transplantation Proceedings, 37, 3433–3434 (2005) 3433