The bioactive peptides generated from whey protein may also serve as endogenous inhibitors of dipeptidyl peptidase-4 (DPP-4) in the proximal gut, preventing incretin (GIP and GLP-1) degradation (19, 20). Indeed, recently DPP-4 inhibitors have been found and identified in Whey protein (21). All these may reduce postprandial blood glucose levels.