Similarly to GLP-1RAs, DPP4is have also been reported to reduce bronchial hyperresponsiveness by increasing endogenous GLP-1 by directly blocking DPP-4, a ubiquitous enzyme that selectively degrades GLP-1 and is upregulated in lung-infiltrating inflammatory cells that perpetuate inflammation in patients with COPD [16]. Here, DPP4 is linked to chronic obstructive pulmonary disease.