Insulin resistance and lung function in obese asthmatic pre-pubertal children

BACKGROUND: Recent findings have supposed that the underlying association between the increased prevalence of both asthma and obesity may be insulin resistance (IR). METHODS: Insulin and glucose serum levels were analyzed to calculate the homeostatic model assessment of insulin resistance (HOMA-IR) for IR in 98 pre-pubertal children. Lung function and allergy status evaluation were performed. The study population was divided into four groups: (1) obese asthmatic children (ObA); (2) normal-weight asthmatic children (NwA); (3) normal-weight non-asthmatic children (Nw) and (4) obese non-asthmatic children (Ob). RESULTS: Forced expiratory volume in 1 s (FEV1) was slightly lower in obese subjects compared with normal-weight subjects and forced vital capacity (FVC) appeared lower in asthmatics, whereas between non-asthmatics subjects, it was lower in the obese group than in the normal-weight one. The post hoc analysis revealed a statistically significant reduction in FEV1, peak expiratory flow (PEF), forced expiratory flows (FEF) between 50% and 25% of the FVC (FEF50 and FEF25) between ObA and Nw and in FEV1, FVC, PEF, FEF50 and FEF25 between NwA and Nw, but no statistically significant differences of lung function parameters were observed between ObA and NwA. We found an inverse relationship between HOMA-IR and all spirometric parameters, although without any statistical significance. We also observed a significantly lower FVC in insulin-resistant children (HOMA-IR>95th percentile) (p=0.03). CONCLUSIONS: This study suggests that lung function could be early altered in obese children, already in pre-pubertal age. Although IR should not manifest its effects on lungs in pre-pubertal obese children, the prevention or treatment of obesity in the pre-pubertal period may prevent definitive negative effects on lungs.