Glutamic Acid Decarboxylase Autoantibodies Are Dominant but Insufficient to Identify Most Chinese With Adult-Onset Non-Insulin Requiring Autoimmune Diabetes: LADA China Study 5

Acta Diabetol. 2015 Dec;52(6):1121-7. doi: 10.1007/s00592-015-0799-8. Epub 2015 Aug 5.

Abstract

Aims: Adult-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.

Methods: LADA 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.

Results: Two 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).

Conclusions: As 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.

Keywords: Glutamic acid decarboxylase antibody (GADA); Insulin autoantibody (IAA); Latent autoimmune diabetes of adults (LADA); Protein tyrosine phosphatase-2 antibody (IA-2A); Zinc transporter 8 autoantibody (ZnT8A).

Publication types

  • Multicenter Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Asian Continental Ancestry Group
  • Autoantibodies / analysis*
  • Biomarkers
  • Cation Transport Proteins / immunology
  • China
  • Diabetes Mellitus, Type 2 / diagnosis*
  • Female
  • Glutamate Decarboxylase / immunology*
  • Humans
  • Islets of Langerhans / immunology
  • Male
  • Middle Aged
  • Prevalence
  • Protein Phosphatase 2 / immunology
  • Zinc Transporter 8

Substances

  • Autoantibodies
  • Biomarkers
  • Cation Transport Proteins
  • SLC30A8 protein, human
  • Zinc Transporter 8
  • Protein Phosphatase 2
  • Glutamate Decarboxylase