Thyroid function and thyroid autoimmunity in type 1 diabetes mellitus: impact on glycemic control

Abstract

Background: The frequency of AITD (autoimmune thyroid disease) and prevalence of thyroid autoantibodies in T1DM (Type 1 diabetes mellitus) patients is much higher than in general paediatric population, varying widely between 3-50% and is often related to age, gender and ethnicity. Although this association has been well established in various populations, very few studies have been done in this regard in South India. The objectives of the study were to study the proportion of abnormal thyroid function and thyroid autoimmunity among T1DM subjects in comparison with general pediatric population and to compare the disease severity among T1DM subjects with and without abnormal thyroid function. Methods: The 45 subjects diagnosed with T1DM (Group 1) and 45 age and gender matched subjects without T1DM (Group 2) were enrolled after applying the inclusion and exclusion criteria. Serum free T3, free T4 and TSH levels were tested for all the subjects in both the groups. In addition, HbA1c levels and Anti TPO antibody titers were tested for subjects with T1DM. Results: Abnormal thyroid function was found in 15.5% of T1DM subjects, in contrast to 2.2% of subjects in the comparison group (p=0.026). The anti-TPO antibody titers were positive in 31.1% of T1DM subjects and among them 42.8% subjects had abnormal thyroid function. T1DM subjects with abnormal thyroid function had significantly higher number of hospitalizations (p<0.05) and total number of ICU admissions (p<0.05) Conclusions: Abnormal thyroid function (predominantly subclinical hypothyroidism) and thyroid autoimmunity was not only more prevalent among T1DM subjects, but was also associated with poor glycemic control. Thus, highlighting the need for screening and a lower threshold for treatment.