The spectrum of thyroid disorders in adult type 1 diabetes mellitus

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Abstract
Background: Thyroid disorders such as goiter, nodules, autoimmune thyroid disease and thyroid dysfunction have rarely been investigated in adult type 1 diabetes mellitus. Our aim was to study the spectrum of thyroid disorders in adult type 1 diabetic subjects and compare them with results obtained from a sample of the general adult population.Methods: The study population comprised 224 type 1 diabetic and 3481 non‐diabetic subjects aged 20–69 years. Thyroid function (TSH, FT3 and FT4) and serum autoantibodies to thyroperoxidase (anti‐TPO‐Ab) were evaluated from blood samples. Thyroid structure and size were measured by ultrasound.Results: Type 1 diabetic subjects had a higher risk of known thyroid disease [odds ratio (OR) 1.78, 95% confidence interval (CI) 1.11–2.85], a lower risk of goiter (OR 0.73; 95%‐CI 0.54–0.99) and nodules (OR 0.54; 95%‐CI 0.35–0.85), and a higher risk of anti‐TPO‐Ab >200 IU/mL (OR 1.94; 95%‐CI 1.28–2.95) compared to the reference population. Furthermore, diabetic subjects had lower serum FT3 levels than the non‐diabetic references (adjusted mean 5.00 pmol/L; 95%‐CI 4.88–5.12 pmol/L versus 5.27 pmol/L; 95%‐CI 5.24–5.30 pmol/L).Conclusions: Adult type 1 diabetes mellitus is associated with a decreased risk of goiter and nodules and an increased risk of thyroid autoimmunity. A diabetes‐related low T3 syndrome may contribute to the differences in thyroid function between type 1 diabetic and non‐diabetic subjects. Copyright © 2006 John Wiley & Sons, Ltd.