Journal of Diabetes Investigation (May 2020)

Increased diagnosis of autoimmune childhood‐onset Japanese type 1 diabetes using a new glutamic acid decarboxylase antibody enzyme‐linked immunosorbent assay kit, compared with a previously used glutamic acid decarboxylase antibody radioimmunoassay kit

  • Shigetaka Sugihara,
  • Ichiro Yokota,
  • Tokuo Mukai,
  • Takahiro Mochizuki,
  • Masashi Nakayama,
  • Emiko Tachikawa,
  • Yasumasa Kawada,
  • Kinship Minamitani,
  • Nobuyuki Kikuchi,
  • Tatsuhiko Urakami,
  • Tomoyuki Kawamura,
  • Eiji Kawasaki,
  • Toru Kikuchi,
  • Shin Amemiya,
  • The Japanese Study Group of Insulin Therapy for Childhood, Adolescent Diabetes (JSGIT)

DOI
https://doi.org/10.1111/jdi.13184
Journal volume & issue
Vol. 11, no. 3
pp. 594 – 602

Abstract

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Abstract Aims/Introduction We compared the results of testing for glutamic acid decarboxylase antibodies (GADAb) using a radioimmunoassay (RIA) and an enzyme‐linked immunosorbent assay (ELISA) in individuals with childhood‐onset type 1 diabetes mellitus. Materials and Methods Serum specimens were collected from 1,024 Japanese children (426 boys and 598 girls) in 2013. The median age at diagnosis was 7 years (0–18 years). The blood specimens were obtained at a median age of 13 years (2–22 years). Results Among the 628 children whose serum specimens were collected within 5 years after diagnosis, the rate of GADAb positivity was 47.9% using RIA and 69.4% using ELISA. The participants were divided into four groups according to their RIA and ELISA results for GADAb as follows: group I (RIA+/ELISA+), group II (RIA+/ELISA−), group III (RIA−/ELISA+) and group IV (RIA−/ELISA−). The clinical and genetic characteristics of group I and group III were quite similar in terms of age at diagnosis, male/female ratio, relatively high positive rates for both autoantibody to protein tyrosine phosphatase IA‐2 and autoantibody to the cation efflux transporter zinc transporter 8, and human leukocyte antigen genotype. Group II contained just five patients, and was characterized by a younger age at diagnosis, low positive rates for both autoantibody to protein tyrosine phosphatase IA‐2 and autoantibody to the cation efflux transporter zinc transporter 8, and a unique human leukocyte antigen genotype. If the positive rates of either autoantibody to protein tyrosine phosphatase IA‐2 or autoantibody to the cation efflux transporter zinc transporter 8 or both were added to the GADAb results using RIA, the percentage of autoimmune type 1 diabetes increased from 47.9% to 78.5%. Conclusions The diagnosis of autoimmune childhood‐onset Japanese type 1 diabetes increased when GADAb results were obtained using a new ELISA method, compared with a previously utilized RIA method.

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