AbstractMetabolic syndrome, including obesity and insulin resistance, has been reported to lower lung function in elderly subjects with asthma or chronic obstructive lung disease. This study aimed to find the association between lung function and insulin resistance in Korean young adults. This study used data from the Korean National Health and Nutrition Examination Survey 2011–2013, which is a representative sample of the Korean population. A total of 1,922 young adults aged 19 to 40 were included in the analysis. The association between lung function test and insulin resistance was evaluated. Weighted logistic regression analyses showed a significant negative correlation of insulin resistance with FVC% predicted (correlation coefficient γ = −0.130, P < 0.0001), FEV₁% predicted (γ = −0.074, P = 0.004) and FEV₁/FVC ratio (γ = −0.059, P = 0.019) in young adults, especially in subjects without asthma (γ for FVC% predicted, FEV₁% predicted and FEV₁/FVC ratio = −0.138, −0.092, and −0.061, respectively). This study demonstrates an inverse correlation between insulin resistance and lung function in Korean young adults. Young adults with preclinical insulin resistance have a higher risk of impaired lung function.