Ethnic group variations in islet autoantibodies in new-onset Type 1 diabetes in a UK cohort (ADDRESS-2)

Background: The influence of ethnicity on the frequency of islet autoantibodies (AAb) in type 1 diabetes is unclear. We investigated differences in frequencies of AAbs to glutamate decarboxylase (GADA), islet autoantigen-2 (IA-2A) and zinc transporter 8 (ZnT8A) in 3 ethnic groups with new-onset T1D: White European (WE), Asian (A), and Black African and Caribbean (AC).

Methods: Adults and children aged 5 or older were recruited within 6 months of a clinician-assigned diagnosis of T1D from 152 secondary care centres in England and Wales. Demographic and clinical data were collected and GADA, IA-2A and ZnT8A measured by radioimmunoassay for individuals who opted to donate a blood sample. Data collected from 2011 to 2017 were analysed if participants were WE, A or AC, had blood samples obtained within 12 months of diagnosis and were positive for at least one AAb.

Results: 1,861 AAb positive participants were included in the analysis, 755 children age <17 (WE: 712, A: 46, AC: 32) and 1,106 adults age&nbsp;?17 (WE:1,071, A:18, AC:17). Median time to blood sampling was 79 days (IQR: 43-127). Within the subgroups of children and adults there were no statistically significant differences between ethnic groups in diabetes presentation (osmotic symptoms, fatigue, weight loss, ketoacidosis) or individual characteristics (age at diagnosis, sex, BMI and family history). For children, the proportions with GADA were similar across ethnic groups (WE:71%, A:89%, AC:87%, p=0.05) but differed for IA-2A (WE:81%, A:41%, AC:60%, p&lt;0.0001) and ZnT8A (WE:69%, A:43%, AC:60%, p=0.01). For adults, no differences were seen in GADA (WE:90%, A:100%, AC:100%, p=0.2) and IA-2A (WE:59%, A:67%, AC:41%, p=0.3), but proportions with ZnT8A differed (WE:53%, A:39%, AC:18%, p=0.006). In conclusion, ethnic group differences in ZnT8A (children and adults) and IA-2A (children only), but not GADA were observed in this UK cohort of people with new-onset T1D.