Prevalence of anti-thyroid peroxidase in adults with type 1 diabetes participating in Poznań Prospective Study.

BACKGROUND: Type 1 diabetes (DM 1) is frequently associated with autoimmune thyroid diseases (AITD). Screening for AITD in adults is rarely performed. The aim of this study was to evaluate the prevalence of anti-thyroid peroxidase (anti-TPO) and thyroid function and their association with metabolic control in adults participating in Poznan Prospective Study (PoProStu).

MATERIAL AND METHODS: The analysis included 74 patients (26 women and 48 men) aged 38.5 (IQR: 34.5-42.5), who have had diabetes for 15.0 (14-16) years. All patients have been treated with intensive functional insulin therapy (IFIT) from the onset of the disease. Anti-TPO and thyroid-stimulating hormone (TSH) were determined. The concentration of anti-TPO ≥ 5.61 IU/mL was considered positive. Based on the levels of anti-TPO the patients were divided into two groups: anti-TPO positive and anti-TPO negative. Metabolic control was assessed by the level of glycated hemoglobin (HbA 1c).

RESULTS: Anti-TPO was positive in 32 (43.2%) patients. Prevalence of autoantibodies was significantly higher in women (53% vs 21%; p = 0.009). There was no significant difference in HbA 1c levels [median (IQR): 7.6% (7.1-8.6) vs 7.6% (7.1-8.8); p = 0.82] and TSH levels [median (IQR): 2.05 µIU/mL (1.23-3.15) vs 1.62 µIU/mL (1.00-2.10); p = 0.06] between anti-TPO positive and negative patients. After excluding patients with a thyroid dysfunction, a significant difference in TSH levels between anti-TPO positive and negative group was found [median (IQR): 2.11 µIU/mL (1.29-3.31) vs 1.66 µIU/mL (1.29-3.31); p = 0.04].

CONCLUSIONS: High anti-TPO prevalence is found in adult patients with long-standing DM 1, and autoantibodies occur more often in women. Therefore, screening for asymptomatic thyroid dysfunction should be performed in this group, as already recommended by the joint statement of Polish Society of Endocrinology and Diabetes Poland.