Obesity-related asthma is a distinct and increasingly common clinical phenotype, characterised by poor symptom control, corticosteroid resistance, and systemic inflammation.1 Metabolic Syndrome (MetS), prevalent in individuals with obesity, may amplify these features through metabolic and inflammatory pathways.2 However, the impact of MetS in asthma is underexplored.3 This cross-sectional study aimed to examine whether MetS is associated with poorer lung function and heightened inflammation in adults with obesity and asthma.
40 adults (56.75±11.71 years old, 57.5% female, BMI 34.82±5.71 kg/m2) with physician-diagnosed asthma and obesity were stratified by MetS status according to the International Diabetes Federation criteria.4 Assessment included lung function (FEV₁, FVC, FEV₁/FVC), asthma control, systemic and airway inflammation (CRP, blood and sputum neutrophils), and metabolic markers (fasting glucose, HOMA-IR). Between-group differences were assessed using appropriate parametric and non-parametric tests, and multivariable regression.
MetS was present in 65% of participants and was associated with significantly greater CRP (p=0.017), blood neutrophils (p=0.024), and inhaled corticosteroid use (p=0.036). Although lung function did not differ significantly by MetS, glucose was inversely correlated with FEV₁ (rs=-0.359, p=0.038), FVC (rs=-0.348, p=0.044), and blood neutrophils (rs=-0.359, p=0.038), indicating that metabolic dysfunction may be associated with both pulmonary impairment and systemic inflammation. There was a correlation between higher fasting blood glucose and airway inflammation (sputum %neutrophils) in females (rs=0.550, p=0.035) but not males (rs=-0.035, p=0.913), suggesting sex-specific effects.
Metabolic Syndrome is associated with increased systemic and airway inflammation in adults with obesity and asthma, suggesting it may contribute to a more severe, metabolically influenced asthma phenotype. Effects appear to be sex-dependent, warranting further research exploring drivers. These findings highlight the clinical relevance of MetS as a treatable trait in obesity-related asthma and underscore the importance of integrated metabolic and respiratory care in this high-risk group.