Thyroid Disorders in Children and Adolescents with Type 1 Diabetes Mellitus in Isfahan, Iran

OBJECTIVE Studies in different populations have shown great variation in the prevalence of thyroid diseases in patients with type 1 diabetes mellitus (T1DM). Our aim was to study the prevalence of thyroid disorders such as autoimmunity of thyroid (AIT), thyroid dysfunction, and goiter in children and adolescents with T1DM, compared with age- and sex-matched healthy controls in Isfahan. METHODS One hundred patients with T1DM who were referred to Isfahan Endocrine and Metabolism Research Center and 184 healthy schoolchildren matched for age and sex were included. They were examined for goiter by two endocrinologists. Thyroid function test and serum thyroid antibodies (anti-TPO Ab and anti-Tg Ab) were measured. FINDINGS The prevalence of subclinical hypothyroidism was high in both groups (18%). T1DM patients had lower frequency of goiter (21% vs. 38%, P=0.001), and higher prevalence of positive AIT (22% vs. 8%, P=0.001), anti-TPO Ab positivity (19.3% vs. 5.3%, P=0.000), and anti-Tg Ab (11.1% vs. 6.4%, P=0.1) in comparison with the control group. Being positive for AIT in diabetic patients meant an odds ratio of 5 (CI 95%: 1.5-15.6) for thyroid dysfunction. There was no association between age, sex, duration of diabetes and HbA(1C) with serum anti-TPO Ab and anti-Tg Ab concentrations in this group. CONCLUSION Our results demonstrated the high prevalence of AIT and thyroid dysfunction in patients with T1DM. We suggest regular thyroid function and antibody testing in these patients.