Is type 2 diabetes a link between lung function and metabolic dysfunction–associated steatotic liver disease? Insights from population studies and Mendelian randomization

Aim: This study aimed to investigate the relationship between lung function and metabolic dysfunction–associated steatotic liver disease (MASLD), and the potential mediating role of type 2 diabetes. Methods Data from the 2007 to 2012 National Health and Nutrition Examination Survey were used. Logistic regression analysis was employed to assess the association between lung function parameters [forced vital capacity (FVC), forced expiratory volume in 1 s (FEV 1 ), FEV 1 /FVC] and MASLD prevalence while exploring type 2 diabetes mediation. Further analyses included linkage disequilibrium score regression, Mendelian randomization, and meta-analysis to examine the causal relationship between lung function and MASLD, considering type 2 diabetes mediation. Results The results showed that higher FVC and FEV 1 levels were associated with decreased MASLD risk, with type 2 diabetes partially mediating this relationship. Genetic analyses supported a causal link between lung function and MASLD, with type 2 diabetes acting as an intermediary. However, no significant association was found between FEV 1 /FVC and MASLD. Conclusion The study identified a causal relationship between lung function and MASLD, with type 2 diabetes playing a partial mediating role.