Glutamic acid decarboxylase autoantibodies are dominant but insufficient to identify most Chinese with adult-onset non-insulin requiring autoimmune diabetes: LADA China study 5.

Yufei Xiang,R David Leslie,Lixin Shi,Zhongyan Shan,Linlin Pan,Shuoming Luo,Qifu Li,Zhiguang Zhou,Liyong Yang,Gan Huang

doi:10.1007/s00592-015-0799-8

Abstract

AimsAdult-onset autoimmune diabetes is prevalent in China, in contrast to childhood-onset type 1 diabetes mellitus. Islet autoantibodies are the most important immune biomarkers to diagnose autoimmune diabetes. We assayed four different islet autoantibodies in recently diagnosed adult non-insulin-requiring diabetes Chinese subjects to investigate the best antibody assay strategy for the correct diagnosis of these subjects.MethodsLADA China study is a nation-wide multicenter study conducted in diabetes patients from 46 university-affiliated hospitals in China. Non-insulin-treated newly diagnosed adult diabetes patients (n = 2388) were centrally assayed for glutamic acid decarboxylase autoantibody (GADA), protein tyrosine phosphatase-2 autoantibody (IA-2A), and zinc transporter 8 autoantibody (ZnT8A) by radioligand assay and insulin autoantibody (IAA) by microtiter plate radioimmunoassay. Clinical data were determined locally.ResultsTwo hundred and six (8.63 %) subjects were autoantibody positive, of which GADA identified 5.78 % (138/2388) of the total, but only 67 % (138/206) of the autoimmune cases. IA-2A, ZnT8A, and IAA were found in 1.51, 1.84, and 1.26 % of the total study subjects, respectively. When assaying three islet autoantibodies, the most effective strategy was the combination of GADA, ZnT8A, and IAA, which could identify 92.2 % (190/206) autoimmune diabetes patients. The clinical data showed that those subjects with positive GADA had lower random C-peptide than autoantibody negative subjects (P < 0.05).ConclusionsAs with Europeans, GADA is the dominant autoantibody in this form of autoimmune diabetes in China, but in contrast to Europeans, screening should include other diabetes-associated autoantibodies.

Highlights

Adult-onset autoimmune diabetes, associated with diabetesassociated autoantibodies, often presents a similar clinical phenotype to type 2 diabetes mellitus [1–3]
When assaying three islet autoantibodies, the most effective strategy was the combination of glutamic acid decarboxylase antibody (GADA), zinc transporter 8 autoantibody (ZnT8A), and insulin autoantibody (IAA), which could identify 92.2 % (190/206) autoimmune diabetes patients
We found that adult-onset autoimmune diabetes is prevalent in China when testing for GADA [1], while ZnT8A augments the detection of latent autoimmune diabetes of adults (LADA) in such Chinese patients [17]

Summary

Results

LADA China is the first multicenter study to investigate adult-onset autoimmune diabetes in recently diagnosed phenotypic type 2 diabetes mellitus subjects in China in terms of the epidemiology, clinical features, and immunogenetic characteristics [1]. From this patient cohort (n = 4880), we assayed 2388 non-insulin-requiring recently diagnosed diabetes patients with sufficient serum. In non-insulin requiring diabetes patients: positivity of GADA, IA-2A, ZnT8A and IAA were 5.8, 1.5, 1.8, and 1.3 % respectively We stratified all these patients by age, i.e., 30–39, 40–49, 50–59 and over 60 years; the four islet autoantibodies did not show any statistical differences between these age subgroups. Compared with type 2 diabetes mellitus patients, clinical and laboratory characteristics of adult-onset autoimmune

Introduction

Conclusions

Compliance with ethical standards