Association of Autoimmune Thyroid Disease with Anti-GAD Antibody ELISA Test Positivity and Risk for Insulin Deficiency in Slowly Progressive Type 1 Diabetes.

Masahito Katahira,Hiromi Takashima,Tsutomu Miwata,Megumi Goto,Hidetada Ogata,Takahiro Ito,Shizuka Nakamura

doi:10.1155/2018/1847430

Abstract

The presence of antiglutamic acid decarboxylase antibody (GADA) is required for the diagnosis of slowly progressive type 1 diabetes (SPT1D). We examined the factors influencing GADA determination by radioimmunoassay (GADA-RIA) and by enzyme-linked immunosorbent assay (GADA-ELISA). Sixty patients with SPT1D and 154 patients with type 2 diabetes were examined by both GADA-RIA and GADA-ELISA and for the presence of autoimmune thyroid disease (AITD). We compared the clinical characteristics of these patients based on the positivity or negativity of GADA-RIA and GADA-ELISA, and the existence or nonexistence of AITD. Thirty of 60 (50.0%) GADA-RIA-positive patients were GADA-ELISA negative, whereas none of the 154 GADA-RIA-negative patients were GADA-ELISA positive. Concomitant AITD was significantly less in patients with GADA-RIA and without GADA-ELISA and was significantly more in patients with GADA-RIA and GADA-ELISA. In GADA-RIA-positive patients, there was no significant difference in the GADA-RIA titer among the GADA-ELISA-negative patients with and without AITD, and the GADA-ELISA-positive patients without AITD; whereas the frequency of insulin deficiency was significantly higher in the patients with AITD and/or GADA-ELISA than in those without AITD and GADA-ELISA. Examination of GADA-ELISA and AITD in GADA-RIA-positive patients might be useful in predicting insulin deficiency in these patients.

Highlights

Type 1 diabetes (T1D) results from β-cell destruction that may lead to a clinical stage in which insulin is required for survival [1]
This study aimed to clarify the differences in the clinical characteristics of patients with slowly progressive T1D (SPT1D) or type 2 diabetes (T2D) based on the positivity or negativity of GADA-RIA and GADA-enzyme-linked immunosorbent assay (ELISA), and the existence or nonexistence of autoimmune thyroid disease (AITD)
The present study suggested that the presence of AITD and/or GADA-ELISA, both of which synergistically elevate the titer of GADA-RIA, might accelerate insulin deficiency in GADA-RIA-positive patients

Summary

Introduction

Type 1 diabetes (T1D) results from β-cell destruction that may lead to a clinical stage in which insulin is required for survival [1]. T1D is divided into three prevalent subtypes: fulminant, acute onset, and slowly progressive [2]. The first two subtypes are abrupt in onset when compared with type 2 diabetes (T2D) and do not necessarily require the presence of islet cell-associated autoantibodies for the diagnosis of T1D [3, 4]. Slowly progressive T1D (SPT1D) is difficult to diagnose based on the mode of onset and requires the presence of antiglutamic acid decarboxylase antibody (GADA) and/or islet cell antibodies (ICA) [5]. The social health insurance in Japan covers the cost of a GADA test, but not an ICA test, and the presence of GADA is virtually essential for the diagnosis of SPT1D. The ELISA kit was characterized by higher sensitivity and increased specificity for the detection of GADA compared with the RIA kit [6]. Oikawa et al reported that the positive rate of GADA by ELISA (GADA-ELISA) had a tendency to be higher than that of GADA by RIA (GADA-RIA) in patients with fulminant and/or acute-onset T1D, and that the former had a tendency to be lower than the latter in patients with

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