Insulin resistance modifies the association between obesity and current asthma in adults

Abstract

Insulin resistance potentiates the association between obesity and childhood asthma, but this relationship appears inconsistent in relatively small studies of adults. We investigated effect modification in adults using the National Health and Nutrition Examination Survey 2003–2012, a large, nationally representative database. Insulin resistance and a history of physician-diagnosed current asthma were obtained from 12 421 adults, ages 18–85 years. We used logistic regression to determine associations between obesity and current asthma, adjusting for age, sex, race/ethnicity, poverty income ratio and smoking status. An interaction term evaluated effect modification by insulin resistance of the obesity–asthma association. As expected, obesity was positively associated with current asthma. Insulin resistance modified this association, with obesity measured as body mass index, waist circumference or waist-to-height ratio. The relationship between obesity and current asthma was stronger with increasing insulin resistance tertiles (OR 2.05, 95% CI 2.76–3.00; p-value for interaction 0.03). This association was robust to adjustments for other components of the metabolic syndrome (hypertriglyceridaemia, hypertension, hyperglycaemia and systemic inflammation). None of these components were themselves effect modifiers of the obesity–asthma association. In this large, nationally representative sample, insulin resistance modified the association between obesity and current asthma in adults. Targeting insulin resistance may represent a novel therapeutic strategy for obese patients with asthma.

Obesity and severe asthma

“…Cardet et al analyzed data from 12,421 adult subjects who participated in NHANES. The authors observed a strong association between obesity and current asthma, as expected, but this relationship was stronger in patients in the highest than the lowest tertile of insulin resistance (68). Insulin resistance also amplifies reductions in lung function in overweight or obese adolescents (69, 70).…”

The impact of therapy on the risk of asthma in type 2 diabetes

“…Obesity is a component of the metabolic syndrome, a cluster of biochemical and physiological parameters that predispose to cardiovascular disease and systemic inflammation . This has led to interest in whether other components of the metabolic syndrome, such as type 2 diabetes, may be independently associated with asthma development …”

Metabolic consequences of obesity as an “outside in” mechanism of disease severity in asthma

“…[9] in this issue of the European Respiratory Journal . These authors investigated associations between obesity and asthma with a focus on effect modification by insulin resistance.…”

“…This finding by Cardet et al . [9] is topical because recent studies in cell culture and mouse models suggest that insulin can cause lung tissue remodelling and worsen lung function [10]. Specifically, it has been shown that insulin stimulates primary human airway smooth muscle cells to proliferate and release collagen [10].…”

“…In this regard, we agree with Cardet et al . [9] that treating insulin resistance may represent a novel therapeutic strategy for obese patients with asthma.…”