Prevalence of subclinical hypothyroidism in women with type 2 diabetes

Background: Subclinical hypothyroidism is a common thyroid disorder. Although there is a recognized association between thyroid disease and diabetes mellitus, there is no definite answer as to whether screening for subclinical hypothyroidism is necessary in patients with type 2 diabetes. The objective of the present study was to evaluate the prevalence of subclinical hypothyroidism in women with type 2 diabetes. Material/Methods: Four hundred ten women with type 2 diabetes (aged 59.6 +/- 10.9 years) and 125 women without diabetes (aged 51.8 +/- 15.8) were studied. Subclinical hypothyroidism was defined as a thyroid stimulating hormone level above the upper normal limit together and a normal free thyroxine level. Measurements of lipids, glycosylated hemoglobin, and antithyroid antibody levels were also performed. Results: After excluding patients with previous thyroid disease, the prevalence of subclinical hypothyroidism was similar between patients with diabetes and control subjects (5.4% vs 7.9%, respectively) (p=0.32). When patients with known thyroid disease were included, the prevalence of subclincal hypothyroidism between groups was similar (9% in diabetes vs 8% in control subjects) (P=0.75). Across all participants, positivity for antithyroid antibody was significantly higher in patients with subclinical hypothyroidism than in euthyroid subjects. Conclusions: The similar prevalence of subclinical hypothyroidism in women with type 2 diabetes and women without diabetes suggests that routine screening of thyroid function in patients with type 2 diabetes is unwarranted.