Autoimmune Thyroiditis in Patients with Type 1 Diabetes Mellitus: A long-term Follow-up Study

Aims: In type 1 diabetes mellitus and autoimmune thyroiditis, there seems to be common genetic loci. The purpose of the present study was to determine whether patients with type 1 diabetes had increased prevalence of autoimmune thyroiditis, and which factors were influencing the co-existence of these two clinical entities.

Patients And Methods: A cohort of 256 patients, 18-79 years of age, a median duration of diabetes of 20 years and a mean follow-up duration of 13 years were included in the study.

Results: Of the 256 patients with type 1 diabetes, 150 participants (58.6%) were women and 106 (41.4%) were men. One hundred and fifty-nine patients (64.6%) did not have autoimmune thyroiditis, whereas 97 (35.4%) had autoimmune thyroiditis, as was documented by the presence of anti-thyroid antibodies (anti-TPO and/or anti-TG). Of the 97 patients with both diabetes type 1 and autoimmune thyroiditis, 64 (66%) were women and 33 (34%) were men. Among the 97 patients who had both diabetes type 1 and autoimmune thyroiditis, 87 had abnormal levels of both anti-TPO and anti-TG, while 7 patients had subnormal levels of solely anti-TPO and only 3 patients had abnormal levels of only anti-TG.

Conclusions: There was a slightly higher prevalence of autoimmune thyroiditis among our patients with type 1 diabetes mellitus. Also, female sex was predominant, when compared to male sex, among the adult participants of this study. Therefore, regular screening of thyroid function and thyroid autoantibodies may be suggested for all patients with type 1 diabetes.