A peptide of the formula (Xaa).sub.n1-Xaa.sub.1-His-Thr-Asp-(Xaa).sub.n2, wherein Xaa is any amino acid; Xaa.sub.1 is a hydrophobic amino acid, preferably Gly or Val; n1 is 0 10; and n2 is 0 10; and use thereof in regulating in vivo blood glucose levels in a human or other mammal, particularly in the treatment of Type 2 diabetes in a human. Preferably, the peptide is a tetrapeptide selected from Gly-His-Thr-Asp and Val-His-Thr-Asp. These hypoglycaemic peptides are isolated from human urine and they also have been chemically synthesized.