Cross-sectional associations of insulin resistance-related indices with self-reported anxious days among U.S. adults

Anxiety is a common mental health condition that substantially impairs quality of life. Emerging evidence suggests that insulin resistance may be related to anxiety symptoms. However, the associations between commonly used insulin resistance-related indices and anxiety symptom burden remain insufficiently characterized in nationally representative populations. We conducted a cross-sectional analysis using data from 5623 U.S. adults aged 20 years and older from the 2007 to 2012 National Health and Nutrition Examination Survey. Anxiety-related symptom burden was assessed as the number of days during the past 30 days that participants reported feeling anxious, tense, or worried. This single self-reported item was analyzed as a continuous outcome and does not constitute a clinical diagnosis of an anxiety disorder. Four insulin resistance-related indices, including the homeostatic model assessment of insulin resistance, triglyceride–glucose index, metabolic score for insulin resistance (METS-IR), and triglyceride/high-density lipoprotein cholesterol ratio, were calculated using standardized laboratory and anthropometric measurements. Survey-weighted multivariable linear regression models were used to examine the associations between these indices and anxiety symptom burden, and restricted cubic spline analyses were performed to explore potential nonlinear patterns. In fully adjusted models, higher levels of homeostatic model assessment of insulin resistance, triglyceride–glucose index, triglyceride/high-density lipoprotein cholesterol ratio, and METS-IR were associated with a greater number of self-reported anxious days, with corresponding β values of 0.11, 0.93, 0.11, and 0.08, respectively. Pairwise Spearman correlation coefficients among the 4 insulin resistance-related indices ranged from 0.465 to 0.899. Quartile-based analyses showed generally similar patterns, although the association for METS-IR was borderline in the fully adjusted model. Restricted cubic spline analyses suggested possible nonlinear associations for some indices. In this nationally representative cross-sectional study, higher insulin resistance-related indices were associated with a greater number of self-reported days of feeling anxious, tense, or worried among U.S. adults. Because the outcome was based on a single nondiagnostic self-reported item, the findings should not be interpreted as evidence of increased clinical anxiety-disorder risk or as support for clinical anxiety discrimination.