CCK and diabetes mellitus: Since 1923, the FDA has approved approximately ten natural peptides for various indications, nine peptides for diabetes, four growth hormone-releasing hormones (GHRH), one cholecystokinin (CCK), two adrenocorticotropic hormones (ACTH), and three analogues of α-melanocyte-stimulating hormone (α-MSH) peptides (FDA) (Figure 1).