The Association Between Insulin Resistance and Vascularization of Thyroid Nodules

Context: Insulin resistance (IR) is an important factor for the growth and progression of thyroid nodules, which might be associated with the distribution, construction, and density of nodular vascularization. Objective: The objective of the study was to explore the association between IR and the vascularization of thyroid nodules. Design and Setting: A cross-sectional, population-based study was conducted in Nanjing, China, from June to November 2011. Participants: Among 10 050 participants aged 40-79 years, 2886 thyroid nodule cases were detected and 2532 cases met eligibility criteria for enrollment in the study. Main Outcome Measures: Power Doppler was performed to measure the flow patterns, resistive index (RI), and vascular index (VI) of thyroid nodular vascularization. Fasting insulin, fasting glucose, 2-hour oral glucose tolerance test, glycosylated hemoglobin (HbA1c), homeostasis model assessment of IR (HOMA-IR), and body mass index were also tested. Results: HOMA-IR (R = 0.35, P < .001) and HbA1c (R = 0.19, P < .001) were positively correlated with thyroid nodular flow patterns, and the positive correlations were more significant in participants with large nodules (volume >= 0.2 mL). Additionally, in participants with large nodules, HOMA-IR and HbA1c were positively correlated with RI (HOMA-IR: beta = .42, SE = .03, R = 0.43, P = .001; HbA1c: beta = .22, SE = .04, R = 0.23, P < .001) and VI (HOMA-IR: beta = .49, SE = 0.05, R = 0.53, P < .001; HbA1c: beta = .34, SE = 0.11, R = 0.37, P < .001). Conclusions: IR and hyperglycemia were positively correlated with the flow patterns, RI, and VI of thyroid nodules, especially in large nodules. The findings suggest a pivotal role of IR in the distribution, construction, and density of thyroid nodular vascularization, which might contribute to the growth and the progression of thyroid nodules.