Endocrine Abstracts

Introduction: Both subclinical hyperthyroidism and type 2 diabetes (T2D) have been associated with an increase in cardiovascular disease risk and mortality. We aimed to assess the prevalence of newly diagnosed subclinical hyperthyroidism in a cohort of patients with T2D, and also to analyse the relationships between diabetes-related characteristics and the presence of subclinical hyperthyroidism.

Methods: Nine hundred and thirty-three diabetic patients without previous history of thyroid disease (45.4% females; mean age, 66.3 year; median duration of diabetes, 10 years; mean HbA1c, 7.8±1.6%) were evaluated. A sample of 911 non-diabetic subjects without known thyroid dysfunction was studied as control group. Serum concentrations of thyrotropin were measured in all subjects. When thyrotropin values were lower than 0.40 mU/l serum concentrations of free thyroxine and triiodothyronine were also quantified.

Results: Subclinical hyperthyroidism was found in 22 female (4.3%) and 15 male (3.5%) diabetic patients. No case of overt hyperthyroidism was found. In comparison with control subjects, the relative risk (OR and 95% confidence interval) for subclinical hyperthyroidism was 1.67 (0.98–2.85). This OR was significant in women (3.69 (1.56–8.71), P=0.001), but not in men (0.78 (0.38–1.61)). In comparison with patients without hyperthyroidism, patients with subclinical hyperthyroidism were older, had longer duration of diabetes, had a higher percentage of goiter, a higher percentage of subjects treated with diet, and a lower percentage of subjects treated with oral antidiabetics. Furthermore, fasting glucose levels were lower in patients with subclinical hyperthyroidism. Logistic regression analysis showed that age and the presence of goiter were significantly related to subclinical hyperthyroidism in patients with T2D.

Conclusion: The risk for subclinical hyperthyroidism is increased in women with T2D. Advanced age and the presence of goiter are significantly and independently related with the presence of subclinical hyperthyroidism in diabetic population.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.