Insulin Resistance Surrogates and Their Associations with Preserved Ratio Impaired Spirometry in United States Adults.

BACKGROUND: /FVC (≥ 0.7), represents an atypical spirometric pattern associated with increased risk of developing chronic obstructive pulmonary disease (COPD), as well as cardiometabolic comorbidities and mortality. Insulin resistance (IR) has been increasingly implicated in pulmonary impairment, yet its association with PRISm remains unclear. METHODS: This study utilized data from 4150 adults in the National Health and Nutrition Examination Survey (NHANES) 2007-2012. Seven IR surrogate indices were evaluated: triglyceride-glucose index (TyG), TyG-BMI, TyG-WC, TyG-WHtR, TG/HDL-C, METS-IR, and estimated glucose disposal rate (eGDR). Weighted multivariable logistic regression assessed associations between each index and PRISm. Weighted linear regression was used to examine associations with lung function parameters. Restricted cubic spline (RCS) analysis evaluated potential nonlinear trends. Subgroup and sensitivity analyses were conducted to test robustness and longitudinal analyses were performed using weighted Cox proportional hazards models. RESULTS: Of the population, 9.20% met PRISm criteria. After full covariate adjustment, higher eGDR was associated with lower PRISm risk (OR: 0.772, 95% CI: 0.703, 0.847, P<0.001), while higher METS-IR and TyG-derived indices (TyG-WHtR: OR: 1.544, 95% CI: 1.349, 1.767, P<0.001) were associated with increased PRISm odds. RCS analysis revealed linear associations for TyG-WC, nonlinear inverse patterns for eGDR and TyG-WHtR, and U-shaped associations for METS-IR and TyG-BMI. Subgroup interactions were most pronounced in hypertensive participants across all IR surrogates (all P-interaction < 0.05). Sensitivity analyses excluding glucose-lowering, lipid-lowering, or respiratory medication users, and stratifying by self-reported health status, confirmed the high robustness of these findings. Weighted Cox models showed that, after full adjustment, TyG-WHtR (HR: 1.267, P = 0.011) and TyG-WC (HR: 1.001, P = 0.025) independently predicted all-cause mortality, with TyG-WHtR exhibiting a time-dependent increase in risk. CONCLUSION: Multiple IR surrogate markers are independently associated with PRISm and reduced lung function in adults. These findings highlight a potential metabolic component in the pathogenesis of PRISm.