Introduction: Type 1 diabetes mellitus (T1DM) is commonly associated with other organ specific autoimmune disorders. Autoimmune thyroid disease (AITD) is the most common comorbid autoimmune condition in patients with T1DM. The occurrence of both T1DM and AITD is defined as Autoimmune Polyglandular Syndrome type 3 variant (APS3v). We sought to clarify thyroid autoimmunity in a cohort of Malaysian patients with T1DM.
Methods: A total of 77 patients (42 girls) with T1DM were followed up over time at the Paediatric Endocrine Unit, Hospital Putrajaya, Malaysia from the period of 2001 to 2019. At diagnosis, all the patients were evaluated for beta cell autoimmunity (antibodies to IA-2, ICA and GAD). Thyroid function tests and autoantibodies to thyroid peroxidase (TPO Ab) and thyroglobulin (TG Ab) were evaluated periodically.
Results: The median age of T1DM patients in the cohort was 13[9 15.5] years. The median age of diagnosis of T1DM was 7[3 10] years with the mean duration of diabetes of 5.9(3.8) years. The prevalence of AITD in the cohort of T1DM patients was 6.5%. One patient was diagnosed with Graves disease prior to the diagnosis of T1DM. The rate at which at least one of the thyroid autoantibodies tested positive (TPO Ab or TG Ab) was 35.3% T1DM/AIT(+). Further analysis revealed, 26.4% had only positive TPO Ab, 2.9% had only positive TG Ab and 8.9% were positive for both TPO Ab and TG Ab. In binary logistic regression analysis, antibodies to GAD was a significant risk factor for the development of thyroid autoantibodies . Additionally, female sex, an older age onset of T1DM, and a higher prevalence of antibodies to GAD were significantly observed in the T1DM/AIT(+) group.
Conclusion: This study demonstrates several differences in the clinical characteristics of T1DM patients with or without thyroid autoimmunity. This finding may indicate a distinct genetic background of these subset of patients and may shed light in the understanding of the pathogenesis of these conditions.
19 - 21 Sep 2019
European Society for Paediatric Endocrinology