title: Glutamic acid decarboxylase autoantibodies are dominant but insufficient to identify most Chinese with adult-onset non-insulin requiring autoimmune diabetes: LADA China study 5.
abstract: OBJECTIVE
  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.
authors.affiliation: Institute of Metabolism and Endocrinology, The Second Xiangya Hospital, Key Laboratory of Diabetes Immunology, Ministry of Education, Central South University, National Clinical Research Center for Metabolic Diseases, Changsha, 410011, China.
authors.forename: Yufei
authors.initials: Y
authors.lastname: Xiang
authors.affiliation: Institute of Metabolism and Endocrinology, The Second Xiangya Hospital, Key Laboratory of Diabetes Immunology, Ministry of Education, Central South University, National Clinical Research Center for Metabolic Diseases, Changsha, 410011, China.
authors.forename: Gan
authors.initials: G
authors.lastname: Huang
authors.affiliation: Department of Endocrinology and Metabolism, Institute of Endocrinology, Liaoning Provincial Key Laboratory of Endocrine Diseases, The First Affiliated Hospital of China Medical University, Shenyang, China.
authors.forename: Zhongyan
authors.initials: Z
authors.lastname: Shan
authors.affiliation: Institute of Metabolism and Endocrinology, The Second Xiangya Hospital, Key Laboratory of Diabetes Immunology, Ministry of Education, Central South University, National Clinical Research Center for Metabolic Diseases, Changsha, 410011, China.
authors.forename: Linlin
authors.initials: L
authors.lastname: Pan
authors.affiliation: Institute of Metabolism and Endocrinology, The Second Xiangya Hospital, Key Laboratory of Diabetes Immunology, Ministry of Education, Central South University, National Clinical Research Center for Metabolic Diseases, Changsha, 410011, China.
authors.forename: Shuoming
authors.initials: S
authors.lastname: Luo
authors.affiliation: The Endocrinology Department, The First Affiliated Hospital of Fujian Medical University, Fuzhou, China.
authors.forename: Liyong
authors.initials: L
authors.lastname: Yang
authors.affiliation: Section of Endocrinology, Affiliated Hospital of Guiyang Medical College, Guiyang, China.
authors.forename: Lixin
authors.initials: L
authors.lastname: Shi
authors.affiliation: Department of Endocrinology, The First Affiliated Hospital of Chongqing Medical University, Chongqing, China.
authors.forename: Qifu
authors.initials: Q
authors.lastname: Li
authors.affiliation: Department of Diabetes and Metabolic Medicine, Blizard Institute, London, UK.
authors.forename: R David
authors.initials: RD
authors.lastname: Leslie
authors.affiliation: Institute of Metabolism and Endocrinology, The Second Xiangya Hospital, Key Laboratory of Diabetes Immunology, Ministry of Education, Central South University, National Clinical Research Center for Metabolic Diseases, Changsha, 410011, China. Zhouzg@hotmail.com.
authors.forename: Zhiguang
authors.initials: Z
authors.lastname: Zhou
mesh_terms: D000328:Adult; D000368:Aged; D044466:Asian People; D001323:Autoantibodies / Q000032:analysis*; D015415:Biomarkers; D027682:Cation Transport Proteins / Q000276:immunology; D002681:China; D003924:Diabetes Mellitus, Type 2 / Q000175:diagnosis*; D005260:Female; D005968:Glutamate Decarboxylase / Q000276:immunology*; D006801:Humans; D007515:Islets of Langerhans / Q000276:immunology; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D054648:Protein Phosphatase 2 / Q000276:immunology; D000075703:Zinc Transporter 8
chemical_list: D001323:Autoantibodies; D015415:Biomarkers; D027682:Cation Transport Proteins; C492522:SLC30A8 protein, human; D000075703:Zinc Transporter 8; D054648:Protein Phosphatase 2; D005968:Glutamate Decarboxylase
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)