Incretin hormones GIP(glucose-dependent insulinotropic polypeptide) and GLP-1 (glucagon-like peptide-1) improve glycemic control by potentiating glucose-induced insulin secretion in pancreatic beta-cells and also have beneficial effects on appetite control and body weight. In response to food ingestion, GIP and GLP-1 are secreted from enteroendocrine K- and L-cells, respectively. In these cells, it is shown that a variety of molecular sensors are involved in the detection of carbohydrates, lipids, and proteins. In view of development of new incretin-related drugs, these sensors are attractive targets to enhance the endogenous pools of incretins.