title: Comparative evaluation of simple indices of graft function after islet transplantation.
abstract: BACKGROUND
  Several simple measures of graft function after islet transplantation have been proposed but a comparative evaluation is lacking. Here, we compared the performance of five indices of β-cell function: β-score, transplant estimated function (TEF), homeostasis model assessment (HOMA) 2-B%, C-peptide/glucose ratio, and Secretory Units of Islets in Transplantation (SUIT).
  
  
  METHODS
  Two cohorts of transplanted patients were analyzed. Cohort 1 consisted of 14 recipients with type 1 diabetes of islet transplantation whereas cohort 2 consisted of 21 recipients with type 1 diabetes of cultured islet cell graft. The five surrogate indices were compared against the first- and second-phase insulin response to arginine in cohort 1, and against the C-peptide response to a hyperglycemic clamp in cohort 2.
  
  
  RESULTS
  We found that the performances of the five surrogate indices were close one to each other in cohort 1. The correlation coefficients ranged 0.62 to 0.67 and 0.62 to 0.68 against the first- and second-phase insulin response to arginine, respectively. In cohort 2, we found that the β-score, TEF, C-peptide/glucose ratio, and SUIT were reasonably well correlated with the clamp response (correlation coefficients were in the range 0.71-0.81), whereas HOMA2-B% showed a modest performance (r=0.54). HOMA2-B% could not be evaluated in one patient whose fasting glucose concentration level was below the lower bound indicated by the HOMA calculator (3 mmol/L). SUIT could not be evaluated in three patients whose fasting glucose concentration was below the glucose threshold of the SUIT formula (3.43 mmol/L).
  
  
  CONCLUSIONS
  In summary, no single index outperformed the others. Nevertheless, when the benefit to cost ratio is considered, TEF stands out for its good performance at a very low cost.
authors.affiliation: Nutrition and Metabolism Unit, Division of Metabolic and Cardiovascular Sciences, San Raffaele Scientific Institute, Milano, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Caumo
authors.forename: Paola
authors.initials: P
authors.lastname: Maffi
authors.forename: Rita
authors.initials: R
authors.lastname: Nano
authors.forename: Livio
authors.initials: L
authors.lastname: Luzi
authors.forename: Robert
authors.initials: R
authors.lastname: Hilbrands
authors.forename: Pieter
authors.initials: P
authors.lastname: Gillard
authors.forename: Daniel
authors.initials: D
authors.lastname: Jacobs-Tulleneers-Thevissen
authors.forename: Antonio
authors.initials: A
authors.lastname: Secchi
authors.forename: Bart
authors.initials: B
authors.lastname: Keymeulen
authors.forename: Daniel
authors.initials: D
authors.lastname: Pipeleers
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Piemonti
mesh_terms: D000328:Adult; D001120:Arginine / Q000494:pharmacology; D001786:Blood Glucose / Q000378:metabolism; D002097:C-Reactive Protein / Q000378:metabolism; D015331:Cohort Studies; D003922:Diabetes Mellitus, Type 1 / Q000097:blood* / Q000601:surgery*; D006085:Graft Survival / Q000502:physiology*; D006706:Homeostasis / Q000502:physiology; D006801:Humans; D007328:Insulin / Q000097:blood; D007515:Islets of Langerhans / Q000187:drug effects / Q000502:physiology*; D016381:Islets of Langerhans Transplantation / Q000502:physiology*; D008875:Middle Aged; D016896:Treatment Outcome
chemical_list: D001786:Blood Glucose; D007328:Insulin; D002097:C-Reactive Protein; D001120:Arginine