Thyroid function and autoantibody status in Bangladeshi patients with type 2 diabetes mellitus

Background: Thyroid dysfunction is common in patients with type 2 diabetes mellitus (T2DM), and data on thyroid autoimmunity in T2DM are scarce. This study was designed to observe the frequency of thyroid dysfunction and autoimmune thyroid disease in Bangladeshi T2DM patients. Materials and Methods: In this cross-sectional study, we investigated 1056 T2DM patients with unknown thyroid function status throughout the country. Serum thyroid stimulating hormone (TSH) and free T4 (FT4) and antithyroid antibodies (antithyroid peroxidase or antimicrosomal) were measured. Statistical analysis was done using IBM SPSS Statistics for Windows, version 23.0 software. P ≤ 0.05 was considered statistically significant. Results: The observed frequency of thyroid dysfunction in our study was 21.9% (subclinical hypothyroid 14.1%, primary hypothyroid 4%, subclinical hyperthyroid 1.9%, overt hyperthyroid 1%, and secondary hypothyroid 0.9%). 32.9% of the participants were positive for thyroid autoantibodies. The patients with thyroid dysfunction had a higher body mass index (BMI), higher TSH, lower FT4, and higher thyroid autoantibody titer than euthyroid ones. Thyroid dysfunction was more common in females and autoantibody-positive individuals. TSH had an inverse negative correlation with FT4 in both euthyroid and thyroid dysfunction groups and had a positive correlation with age in the euthyroid group only. FT4 had an inverse correlation with age and duration of diabetes in both groups and with BMI in euthyroid diabetic patients. Conclusion: Thyroid dysfunction and autoimmunity are common in Bangladeshi T2DM patients. Thyroid dysfunction was more common in females and autoantibody-positive diabetic patients.