Endocrine Abstracts

Objective: Genetic susceptibility to autoantibody formation in association with autoimmune thyroid disease and type 1 diabetes mellitus has been described with varying frequencies. We have, therefore, investigated the prevalence of anti-thyroid peroxidase (anti-TPO), overt and subclinical hypothyroidism in type 1 diabetic patients.

Methods: Sixty-five subjects with type 1 diabetes mellitus and 65 unrelated normal controls were recruited for the detection of anti-TPO and Thyroid-stimulating hormone (TSH). Written informed consent was obtained after the procedure had been fully explained.

Results: Among 65 type 1 diabetic patients, 18 (27.7%) were positive for anti-TPO and 18 (27.7%) had abnormal serum TSH level. Among these patients 11 (16.0%) had overt hypothyroidism and 7 (10.8%) had subclinical hypothyroidism. Compared with those without thyroid autoimmunity, there was a female preponderance for the type 1 diabetic patients with thyroid autoimmunity (female:male, 24:23 vs 11:7 respectively). Patients with thyroid antibodies were older, had a longer duration of diabetes (17.6±9.3 vs 10.8±7.8 years), and developed diabetes later in life than those without antibodies. The mean anti-TPO levels were higher in patients with overt hypothyroidism (238.18±223.69 U/ml) than in patients with subclinical hypothyroidism (36.38±22.46 U/ml). Among 11 patients with overt hypothyroidism 9 (81.1%) had abnormal anti-TPO levels, whereas positive anti-TPO were detected in 57% of patients (4:7) with subclinical hypothyroidism.

Conclusion: The presence of anti-TPO in 27.7% of our type 1 diabetic patients confirmed the strong association of autoimmune thyroid disease and type 1 diabetes mellitus. For early detection of autoimmune thyroid disease in patients with type 1 diabetes mellitus, measurement of anti-TPO and TSH preferably at type 1 diabetes mellitus onset is recommended.