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 years) 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.
Material and Method

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 subclinical 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.

Keywords: Israel - epidemiology, Hypothyroidism - epidemiology, Diabetes Mellitus, Type 2 - complications, Case-Control Studies, Prevalence