GLP1R and type 2 diabetes mellitus: These approaches have supported successful oral delivery of several peptides/proteins, including semaglutide (a glucagon-like peptide 1 receptor agonist) for treating type 2 diabetes [78,79,81], desmopressin (an analog of vasopressin) for treating diabetes insipidus [60,81], and linaclotide for treating irritable bowel syndrome and constipation [60].