Autoimmune Thyroid Disease Correlates to Islet Autoimmunity on Zinc Transporter 8 Autoantibody: A Cross-Section Study

Abstract Background The most common coexisting organ-specific autoimmune disease in patients with Type 1 diabetes mellitus (T1DM) is autoimmune thyroid disease (AITD). Many studies have showed prevalence rate of thyroid autoantibodies range from 3.7-35% in T1DM patients, while some of them suggested the associations between thyroid autoantibodies and islet autoantibodies. However, little work has been done about the anti-islet autoimmune status in patients with autoimmune thyroid disease (AITD), and so far there have been no clinical report based on large population about zinc transporter 8 autoantibody (ZnT8A) in patients with AITD. We aimed to explore the presence of islet autoantibodies, ZnT8A, glutamic acid decarboxylase autoantibodies (GADA) and tyrosine phosphatase autoantibodies (IA-2A) compared with thyroid autoantibodies, thyroid peroxidase autoantibodies (TPOAb) and thyroglobulin autoantibodies (TGAb) and thyrotropin receptor autoantibodies (TRAb) in AITD patients. Methods In total 740 AITD patients, 108 type 1 diabetes mellitus (T1DM) patients with AITD, 172 non-autoimmune thyroid disease (nAITD) patients and 115 healthy controls were recruited in the cross-sectional study. Islet autoantibodies, ZnT8A, GADA, IA-2A and thyroid autoantibodies, TPOAb, TGAb, TRAb were detected with Radioimmunoassay and Chemiluminescence. Islet autoantibody relative value was established to compare the distribution of the three islet autoantibodies. Results The prevalence of ZnT8A and GADA in AITD group was significantly higher than that in healthy controls (ZnT8A: 15.00% vs 1.74%, GADA: 7.97% vs 0.87%, both P<0.05). Similarly, the prevalence of IA-2A in AITD group was higher than that in healthy controls (4.19% vs 0%, P<0.05). However, any islet autoantibodies positive rate in AITD group was significantly lower than that in T1DM with AITD group. Analysis of multivariable linear regression suggested that ZnT8A relative value was positively related with GADA relative value (β=0.352, P<0.01) and TPOAb titer (β=0.002, P<0.01), and GADA relative value was also positively related with ZnT8A relative value (β=0.183, P<0.01). Conclusions An increased prevalence of ZnT8A as well as a relatively high prevalence of islet autoimmunity was found in AITD patients, indicating that there is a potential link between thyroid autoimmunity and islet autoimmunity. Trial registration Retrospectively registered.