Endocrine Abstracts

Background: We investigated the frequency of autoimmune thyroid and diabetes antibodies in patients with type 1 diabetes mellitus (T1DM), their siblings, and controls.

Methods: Glutamic acid decarboxylase antibodies (GADA), islet cell antibodies (ICA), insulin autoantibodies (IAA), and thyroid antibodies were identified in all subjects.

Results: The rates of positive GADA and IAA were significantly higher in probands compared to siblings (P<0.001) and controls (P<0.001). None of the pancreatic autoantibodies were different between siblings and healthy controls. Thyroid antiperoxidase antibody (TPOAb) and antithyroglobulin antibody (TGAb) were significantly different between probands and control subjects (P=0.002 and P=0.018, retrospectively). The positive rates of TPOAb and TGAb in siblings were higher than those of controls, but no differences were detected between the groups. Thyroid autoimmunity (TA) was significantly different among the groups (P=0.004). Siblings of TA-positive probands revealed a greater prevalence of thyroid autoantibodies than did the control subjects (P=0.022), whereas siblings of TA-negative probands did not show such an increase over controls.

Conclusion: The prevalence of pancreatic and thyroid antibody positivity in probands was statistically significant compared to siblings and controls. Siblings of TA-positive probands revealed a greater prevalence of thyroid autoantibodies than did the control subjects. So the screening for TA in siblings, particularly siblings of TA-positive probands, is as important as in probands.