Background: A positive association between air pollution and insulin resistance has been shown in previous studies as a precursor state of type 2 diabetes, especially in older adults. This study was conducted to investigate the association between insulin resistance and environmental polycyclic aromatic hydrocarbon (PAH) exposure as ubiquitous outdoor and indoor air pollution components. Methods: From the second Korean National Environmental Health Survey, 5,717 adults aged ≥19 years were included in this study. To identify the association between environmental PAH exposure (urinary 1-hydroxypyrene, 1-OHP) and insulin resistance, defined by the ratio of triglyceride to high-density lipoprotein cholesterol, we performed multiple stepwise regression analysis, adjusting for age, sex, education, physical activity, exposure to smoking and air pollution, body mass index, hypertension, and diabetes mellitus. Results: Urinary 1-OHP concentration was significantly associated with the ratio of triglyceride to high-density lipoprotein cholesterol. Conclusion Environmental exposure to PAHs is associated with increased insulin resistance in adults.