Dipeptidyl peptidase Ⅳ (DPPIV; also known as CD26) is a serine protease and expressed ubiquitous as a homodimer on the cell surface of a variety of tissues and organs, and it also occurs in soluble form in serum.As serine exopeptidase, DPPIV cleaves N-terminal dipeptides from polypeptides with proline or alanine preferentially in the penultimate position,thereby regulating the activity of a variety of biologically important peptides (1).Recently two major insulin-releasing hormones, also known as incretin, glucagons-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), were shown to be substrates for the DPPIV.GLP-1 and GIP are arise from intestinal L-cell and K-cells, respectively,and was shown to enhance insulin secretion in the presence of elevated glucose concentration.With the exogenous administration of GIP and GLP-1, glucose concentrations can be reduced to within the normal range, even in patients with advanced type Ⅱ diabetes.