Objective: Recent epidemiological evidence suggests that subclinical hypothyroidism (SCH), defined as elevated TSH concentrations with normal circulating levels of triiodothyronine (T3) and thyroxine (T4), is associated with dyslipidemia and cardiovascular disease in adult populations. As currently no data are available on the prevalence of SCH and its potential association with lipoprotein profile in children and adolescents with type 1 diabetes (T1DM), we investigated the prevalence of SCH and associated lipid levels in young diabetic patients.
Design and methods: Cross-sectional analysis of 22,747 children, adolescents, and young adults (age <25 years) with T1DM with normal T3 and T4 and either normal TSH (≥0.5 to <4.0 mIU/l, euthyroid group) or elevated TSH (≥4.0 to <25.0 mIU/l, SCH group) and simultaneous measurement of serum lipid and lipoprotein status.
Results: The prevalence rate of SCH in the study population was 7.2%. Adjusted for age, gender, diabetes duration, current insulin dose, HbA1c, and BMI z-score, patients with SCH had significantly higher levels of total cholesterol (178.7 vs 175.3 mg/dl, P<0.001) and LDL-cholesterol (97.0 vs 93.7 mg/dl, P<0.001) compared with euthyroid patients.
Conclusions: SCH is a common finding in children, adolescents, and young adults with T1DM. SCH is associated with increased levels of total cholesterol, and LDL-cholesterol adjusted for potential confounders. SCH-associated increases in lipid and lipoprotein levels may therefore add to an increased long-term cardiovascular risk in young patients with T1DM.