The last line is pharmacochemical and deals with derivatization of bioactive peptides to become useful drugs (‘peptide therapeutics’).20,21 Recently, interest has focused on gut hormones with incretin-activity where, in particular, glucagon-like peptide-1 (GLP-1)-derived drugs have been applied to the treatment of type 2 diabetes mellitus.22, -24 There are, however, considerable amounts of evidence to suggest that also other gastrointestinal hormones may prove valuable in diabetes therapy. Here, GCG is linked to diabetes mellitus.