Previous studies showed that WC pos

Previous studies showed that WC positively correlatedwith insulin resistance and was a predictive factor forinsulin resistance.14 Insulin resistance was related to thedistribution, structure, and density of thyroid blood vessels, which might promote the growth of nodules. Insulinresistance may directly activate the proliferation pathwaythrough insulin or insulin-like growth factor 1 and regulatethe expression of thyroid genes and the proliferation anddifferentiation of thyroid cells.15 Thyroid cells maysynthesize insulin-like growth factor 1 and express insulin-like growth factor 1 receptor. The expression level ofinsulin-like growth factor 1 was higher in thyroid cellswith nodules than in those without nodules. In patientswith insulin resistance, the volumes of thyroid nodulesdecreased obviously after metformin treatment for sometime,16 further proving the relationship between insulinresistance and thyroid nodules.Bastemir et al found that the TSH levels were significantly higher in obese people than in normal people. Theyalso pointed out that the TSH level positively correlatedwith weight, BMI, and WC levels.17 In the present study,the TSH level was higher in patients with WC ≥90 cm thanin those with WC