HAEGT is the first N-terminal 1-5 residues of glucagon like peptide-1 (GLP-1) peptide, and the sequence is His-Ala-Glu-Gly-Thr. HAEGT acts as a competitive substrate for probing prime substrate binding sites of human dipeptidyl peptidase-IV (DPP-IV) 1, in which the N-terminal His-Ala is catalyzed cleavage by DPP-IV. HAEGT can be used in the research of diabetes, obesity.