Zinc transporter 8 autoantibody (ZnT8A) could help differentiate latent autoimmune diabetes in adults (LADA) from phenotypic type 2 diabetes mellitus

Background The ZnT8A is an independent marker for diagnosis of type 1 diabetes mellitus. We investigated the distribution and clinical features of ZnT8A positive latent autoimmune diabetes in adult (LADA) patients to explore the potential diagnostic application. Methods A total of 3062 phenotypic T2DM patients were randomly selected from a national multicenter study - the LADA China Study. Radioligand binding assays were applied to detect the presence of ZnT8A, GADA and IA-2A. HbA(1c), fasting C-peptide and serum lipid levels were followed up with ZnT8A positive patients. Results The positive prevalence of ZnT8A, GADA and IA-2A in phenotypic T2DM patients was 1.99%(61/3062), 6.43% (197/3062) and 1.96% (60/3062), respectively. The ZnT8A positivity was lower than that of GADA(x(2)= 74.8, p< 0.001) but was comparable with that of IA-2A(p> 0.05). The positivity of ZnT8A in IA-2A positive patients was higher than that in GADA positive patients (38.3% vs. 10.7%, x(2)= 24.8, p< 0.001). On the basis of GADA and IA-2A positivity, the ZnT8A assay enhanced the diagnostic prevalence of LADA from 7.58 to 8.62%. The LADA patients who were positive for ZnT8A had higher systolic blood pressure when compared with GADA positive cases(p= 0.049) and higher total cholesterol levels when compared with antibody-negative T2DM patients(p= 0.035). Conclusion The detection of ZnT8A at the basis of GADA and IA-2A can improve diagnostic sensitivity of Chinese LADA. Copyright (C) 2013 John Wiley & Sons, Ltd.