Studies have shown that compared with healthy subjects, the systemic levels of testosterone, IGF-1, and DHEA in COPD patients are significantly reduced and negatively correlated with serum IL-6 levels, and the IL-6/DHEA ratio was found to increase gradually with the exacerbation of peripheral muscle atrophy (Debigare et al., 2003). This evidence concerns the gene IGF1 and chronic obstructive pulmonary disease.