Association of triglyceride-glucose index and lung health: a population-based study.

Abstract Background Metabolic syndrome and insulin resistance are associated with worsened outcomes of chronic lung disease. The triglyceride-glucose index (TyG), a measure of metabolic dysfunction, is associated with metabolic syndrome and insulin resistance, but its relationship to lung health is unknown. Research Question What is the relationship of TyG to respiratory symptoms, chronic lung disease, and lung function? Study Design and Methods: We analyzed the National Health and Nutrition Examination Survey from 1999-2012. Participants included fasting adults age ≥40 years (n=6,893) with lung function measurements in a subset (n=3,383). Associations of TyG with respiratory symptoms (cough, phlegm production, wheeze, exertional dyspnea), chronic lung disease (diagnosed asthma, chronic bronchitis, emphysema), and lung function (FEV1, FVC, and obstructive or restrictive spirometry pattern) were evaluated adjusting for sociodemographic variables, comorbidities, and smoking. TyG was compared to insulin resistance, represented by the homeostatic model assessment of insulin resistance (HOMA-IR), and to metabolic syndrome. Results TyG was moderately correlated with HOMA-IR (ρ=0.51) and had good discrimination for metabolic syndrome (AUROC=0.80). A one-unit increase in TyG was associated with higher odds of cough (adjusted odds ratio [aOR] 1.28; 95% confidence interval [CI] 1.06-1.54), phlegm production (aOR 1.20; 95%CI 1.01-1.43), wheeze (aOR 1.18; 95%CI 1.03-1.35), exertional dyspnea (aOR 1.21; 95%CI 1.07-1.38), and a diagnosis of chronic bronchitis (aOR 1.21; 95%CI 1.02, 1.43). TyG was associated with higher relative risk of a restrictive spirometry pattern (adjusted relative risk ratio 1.45; 95%CI 1.11-1.90). Many associations were maintained with additional adjustment for HOMA-IR or metabolic syndrome. Interpretation TyG was associated symptoms, chronic bronchitis, and restrictive spirometry. Associations were not fully explained by insulin resistance or metabolic syndrome. TyG is a satisfactory measure of metabolic dysfunction with relevance to pulmonary outcomes. Prospective study to define TyG as a biomarker for impaired lung health is warranted.