The association between insulin use and asthma: an epidemiological observational analysis and Mendelian randomization study

Abstract

Abstract Background Asthma is a common respiratory disease caused by genetic and environmental factors, but the contribution of insulin use to the risk of asthma remains unclear. This study aimed to investigate the association between insulin use and asthma in a large population-based cohort, and further explore their causal relationship by Mendelian randomization (MR) analysis. Methods An epidemiological study including 85,887 participants from the National Health and Nutrition Examination Survey (NHANES) 2001–2018 was performed to evaluate the association between insulin use and asthma. Based on the inverse-variance weighted approach, the MR analysis involving multiple cohorts was conducted to estimate the causal effect of insulin use on asthma. Results In the NHANES cohort, we found that insulin use was associated with an increased risk of asthma (odd ratio [OR] = 1.38; 95%CI: 1.16–1.64; p < 0.001). For the MR analysis, we found a causal relationship between insulin use and a higher risk of asthma in both Finn (OR = 1.10; p < 0.001) and UK Biobank cohorts (OR = 1.18; p < 0.001). Meanwhile, there was no causal association between diabetes and asthma. After multivariable adjustment for diabetes, the insulin use remained significantly associated with an increased risk of asthma (OR = 1.17, p < 0.001). Conclusions An association between insulin use and an increased risk of asthma was found via the real-world data from the NHANES. In addition, the current study identified a casual effect and provided a genetic evidence of insulin use and asthma. More studies are needed to elucidate the mechanisms underlying the association between insulin use and asthma.