Of the components of metabolic syndrome, only IR has been shown to modify the effect of obesity on asthma. The current study showed that IR has a negative effect on lung function and the efficacy of standard asthma treatments in patients with asthma.
Even though the pathophysiologic basis for decreased lung function in patients with asthma and IR or hyperinsulinemia has not been established, treatment of IR with insulin sensitizers may not only preserve lung function long-term, but normalize the treatment response to bronchodilators and corticosteroids.
Data were obtained from the Severe Asthma Research Program 3. HOMA-IR values, and before and after treatment (inhaled albuterol and intramuscular triamcinolone acetonide) and lung function (FEV1 and FVC) values were determined yearly x 5 y.
Three hundred seven patients with asthma were studied: 170 were obese and 140 had IR.
The FEV1 and FVC were lower in patients with IR than patients without IR and independent of obesity. Furthermore, the FEV1 was lower in response to treatment in patients with IR compared to patients without IR.
The annualized decrease in FEV1 was as follows: moderate IR, -41 ml/y; severe IR, -32 ml/y; and no IR, -13 ml/y.