Insulin Resistance in Patients with Benign Thyroid Nodules.

OBJECTIVE Recently, it has been questioned whether insulin resistance is associated with thyroid nodules. The aim of this study was to examine insulin resistance prevalence in a case-control study of patients with benign thyroid nodules in an iodine-sufficient area. METHODS This was a single-center, case-control study on euthyroid patients with benign nodular diseases. Thirty newly diagnosed patients with benign thyroid nodules according to fine needle aspiration cytology were investigated for insulin resistance. As a control group, 30 euthyroid control subjects with normal thyroid sonography without nodule were recruited from the general population. The participants were matched in pairs by age, gender, and body mass index. The diagnosis of insulin resistance was made when the homeostasis model assessment of insulin resistance (HOMA-IR) index was more than 2.5. RESULTS The mean of HOMA-IR value was significantly higher in patients compared to controls (1.32 ± 0.65 vs. 0.76 ± 0.36, P-value < 0.001). Insulin resistance was seen in two subjects with thyroid nodules (6.7%), but none in the control group. There was a positive significant correlation between HOMA-IR and thyroid nodule size (r-value: +0.38, P < 0.03). CONCLUSION Patients with thyroid nodules have higher HOMA-IR value. There is an association between insulin resistance and benign thyroid nodules. More investigations are required to define the role of this factor in thyroid nodule formation.