DPP4 and obesity due to melanocortin 4 receptor deficiency: Circulation of active GLP-1 (7–36) hormone is short-lived due to its rapid cleavage into inactive GLP-1 (9–36) by dipeptidyl peptidase-4 (DPP-4) Boer and Holst, 2020; DPP-4-resistant peptide analogues of GLP-1 have, therefore, been developed and successfully used clinically for the treatment of T2D and obesity, including exendin-4, liraglutide, and semaglutide, amongst others (de Graaf et al., 2016; Boer and Holst, 2020; Drucker and Holst, 2023).