title: Secretory units of islets in transplantation index is a useful predictor of insulin requirement in Japanese type 2 diabetic patients.
abstract: OBJECTIVE
  The objective of the present study was to clarify the validity of β-cell function-related parameters for predicting the insulin requirement of Japanese type 2 diabetic patients.
  
  
  METHODS
  In 188 patients with type 2 diabetes who had been admitted to the University of Toyama Hospital (Toyama, Japan) without receiving insulin therapy, we carried out a cross-sectional study examining the relationship between the homeostasis model assessment of β-cell function (HOMA-β) and C-peptide-based indices, and also carried out a retrospective study to examine the utility for predicting insulin requirement of several β -cell function-related indices using a receiver operating characteristic (ROC) curve analysis.
  
  
  RESULTS
  The secretory units of islets in transplantation index (SUIT) had the strongest correlation with HOMA-β, followed by the fasting serum C-peptide immunoreactivity index (CPI); the fasting serum C-peptide immunoreactivity itself (F-CPR) had the least correlation. The CPI, HOMA-β and SUIT were significantly lower in the insulin-requiring group than in the non-insulin-requiring group, even after adjustments for confounding factors (P < 0.01). The areas under the ROC curve for insulin requirement were 0.622, 0.774, 0.808, and 0.759 for F-CPR, CPI, SUIT, and HOMA-β, respectively. The cut-off values of SUIT, CPI, and HOMA-β for an over 80% specificity for the prediction of insulin therapy were 23.5, 1.00, and 14.9, respectively.
  
  
  CONCLUSIONS
  The present study shows that SUIT is the best predictor of insulin requirement among these β-cell function-related markers.
authors.affiliation: First Department of Internal Medicine University of Toyama Toyama Japan ; Community Medical Support Unit Faculty of Medicine University of Toyama Toyama Japan.
authors.forename: Minoru
authors.initials: M
authors.lastname: Iwata
authors.affiliation: Department of Clinical Research National Center for Global Health and Medicine Tokyo Japan.
authors.forename: Yumi
authors.initials: Y
authors.lastname: Matsushita
authors.affiliation: First Department of Internal Medicine University of Toyama Toyama Japan.
authors.forename: Kazuhito
authors.initials: K
authors.lastname: Fukuda
authors.affiliation: First Department of Internal Medicine University of Toyama Toyama Japan.
authors.forename: Tatsurou
authors.initials: T
authors.lastname: Wakura
authors.affiliation: First Department of Internal Medicine University of Toyama Toyama Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Okabe
authors.affiliation: First Department of Internal Medicine University of Toyama Toyama Japan.
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Koshimizu
authors.affiliation: Department of Internal Medicine Asahi General Hospital Asahi-machi Japan.
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Fukushima
authors.affiliation: Department of Internal Medicine Kamiichi General Hospital Kamiichi-machi Japan.
authors.forename: Chikaaki
authors.initials: C
authors.lastname: Kobashi
authors.affiliation: Department of Internal Medicine Saiseikai Toyama Hospital Toyama Japan.
authors.forename: Yu
authors.initials: Y
authors.lastname: Yamazaki
authors.affiliation: Division of Endocrinology and Metabolism Department of Internal Medicine Saiseikai Takaoka Hospital Takaoka Toyama Japan.
authors.forename: Hisae
authors.initials: H
authors.lastname: Honoki
authors.affiliation: Department of Internal Medicine Shakaihoken Takaoka Hospital Takaoka Toyama Japan.
authors.forename: Hikari
authors.initials: H
authors.lastname: Suzuki
authors.affiliation: Department of Public Health University of Toyama Toyama Japan.
authors.forename: Mika
authors.initials: M
authors.lastname: Kigawa
authors.affiliation: First Department of Internal Medicine University of Toyama Toyama Japan.
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Tobe
keywords: Insulin requirement; Type 2 diabetes; β‐cell function