On the other hand, results from observational studies have yielded counter-observations, reporting lower hHF risk associated with DPP-4i use compared with GLP-1 receptor agonists, with no significant difference in patients with a history of heart failure [34], and no difference in the risk of hHF when DPP-4i use was compared with sulfonylurea [35]. This evidence concerns the gene GLP1R and heart failure.