Influence of long-term statin use in type 2 diabetic patients on thyroid nodularity in iodine-sufficient area

Statins have marked beneficial effects on lipid profile, but also have pleiotropic actions. A previous study in an iodine-deficient area suggested that statin use is associated with reduced thyroid volume and nodularity. We performed this study to investigate how long-term statin use in type 2 diabetic patients affects thyroid nodularity in iodine-sufficient area.We recruited euthyroid type 2 diabetic patients, receiving statin therapy continuously for at least 5 years (statin group) and, age and sex matched statin-naive type 2 diabetic patients (control group). Subjects with past history of cancer, thyroid disease or treatment with lithium or amiodarone; family history of thyroid cancer; palpable goiter or thyroid nodule, and/or positive thyroperoxidase antibody were excluded. The prevalence, number, and volume of thyroid nodules, size of thyroid were evaluated in all subjects by high resolution ultrasound.Prevalence of non-palpable thyroid nodules of statin group (n=70) and control group (n=98) were 51 and 53%, respectively. There was no difference of prevalence, number, and volume of non-palpable thyroid nodules and size of thyroid between statin and control group. But, the patients aged between 60 and 65 years from statin group showed lower prevalence of non-palpable thyroid nodules than the patients with same age interval from control group (4 out of 12 patients, 33%, statin group; 19 out of 27 patients, 70%, control group; P=0.04).Long-term statin use in elderly type 2 diabetic patients was associated with lesser prevalence of thyroid nodules in an iodine-sufficient area. Our data might support a possible antiproliferative effect of statins on thyroid in old type 2 diabetic patients. But, the effect was not as strong as that in an iodine-deficient area and further studies with enough numbers of subjects and revised design will be needed.