title: Simple measures to monitor beta-cell mass and assess islet graft dysfunction.
abstract: The aim of this study was to develop a simple test for the assessment of islet graft dysfunction based on measures involving fasting C-peptide. Calculations were made to account for the dependence of C-peptide secretion on glucose concentration (C-peptide/glucose ratio [CP/G]) and adjusted for renal function by calculating the C-peptide/glucose-creatinine ratio (CP/GCr). Values from 22 recipients were analyzed at different times post-last islet infusion. Receiver operating characteristic curves were used to determine which of these measures best predicts high 90-minute glucose (90 min-Glc; >10 mmol/L) after a Mixed Meal Tolerance Test (MMTT). In this initial analysis, CP/G was found to be superior predicting high 90 min-Glc with a larger area under the ROC curve than C-peptide (p = 0.01) and CP/GCr (p = 0.06). We then correlated C-peptide and CP/G with islet equivalents--IEQ/kg infused, 90 min-Glc after MMTT and clinical outcome (beta-score). C-peptide and CP/G in the first 3 months post-last islet infusion correlated with IEQ/kg infused. CP/G correlated with 90 min-Glc and beta-score. C-peptide and CP/G are good indicators of islet mass transplanted. CP/G is more indicative of graft dysfunction and clinical outcome than C-peptide alone. The ease of calculation and the good correlation with other tests makes this ratio a practical tool when monitoring and managing islet transplant recipients.
authors.affiliation: Clinical Islet Transplant Program at the Diabetes Research Institute, University of Miami Leonard M. Miller School of Medicine, Miami, Florida, United States.
authors.forename: R N
authors.initials: RN
authors.lastname: Faradji
authors.forename: K
authors.initials: K
authors.lastname: Monroy
authors.forename: S
authors.initials: S
authors.lastname: Messinger
authors.forename: A
authors.initials: A
authors.lastname: Pileggi
authors.forename: T
authors.initials: T
authors.lastname: Froud
authors.forename: D A
authors.initials: DA
authors.lastname: Baidal
authors.forename: P E
authors.initials: PE
authors.lastname: Cure
authors.forename: C
authors.initials: C
authors.lastname: Ricordi
authors.forename: L
authors.initials: L
authors.lastname: Luzi
authors.forename: R
authors.initials: R
authors.lastname: Alejandro
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D002096:C-Peptide / Q000097:blood*; D003404:Creatinine / Q000097:blood; D005260:Female; D006084:Graft Rejection / Q000097:blood* / Q000175:diagnosis / Q000503:physiopathology*; D006801:Humans; D050417:Insulin-Secreting Cells / Q000473:pathology*; D016381:Islets of Langerhans Transplantation / Q000473:pathology / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012372:ROC Curve; D012189:Retrospective Studies; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D001786:Blood Glucose; D002096:C-Peptide; D003404:Creatinine