Endocrine Abstracts

Introduction: Coexistence of type 1 diabetes mellitus (DM) and autoimmune thyroid diseases was shown in previous studies. Thyroid dysfunctions and thyroid autoantibody positiveness were reported in 23–25 and 27–44% of patients with type 1 DM, respectively. In recent years, thyroid ultrasonography (US) is widely used to diagnose autoimmune thyroid diseases with regard to its ability to define thyroid morphology and echogenity. In this study, we aimed to evaluate thyroid functions, autoantibodies and US features in Type 1 DM patients.

Material and method: We retrospectively analyzed 104 Type 1 DM patients (53 females, 51 males) followed in our clinic. Patients were matched with 58 healthy controls (27 females, 31 males) according to age and sex. Serum thyrotropin (TSH), thyroid hormones and thyroid autoantibodies were evaluated. Thyroid US was performed in all subjects.

Results: Mean ages of Type 1 DM patients and control group were 31.08±9.38 and 27.59±7.17, respectively. Median TSH and fT3 were similar in Type 1 DM patients and control subjects, however median fT₄ was significantly higher in patient group (P≤0.001). Of 26.3% of diabetic patients and 3.7% of control subjects had at least one of the thyroid autoantibodies (P≤0.001.). Prevalence of thyroid dysfunctions was significantly higher in Type 1 DM patients compared to control subjects (28.8 vs 3.4%, P≤0.001). In thyroid US, thyroid parenchyma was homogenous in 22.1% and heterogenous in 78.9% of patients, while it was homogenous in 91.4% of healthy controls. Similar rates of thyroid nodules were observed in the two groups.

Conclusion: Patients with Type 1 DM have higher rates of thyroid dysfunctions, autoantibody positivity and ultrasonographical abnormalities. Morphological abnormalities of thyroid gland are closely associated with thyroid autoantibody positivity and thyroid dysfunctions in Type 1 DM patients indicating the need for close follow-up in patients with abnormal US features.