Intestinal enteroendocrine cells (IECs) secrete gut peptides in response to both nutrients and non-nutrients. Glucose and amino acids both stimulate gut peptide secretion. The gut hormone gluco-insulinotropic peptide (GIP) is secreted from IEC K-cells and the gut hormones glucagon-like peptide-1 (GLP-1) and peptide tyrosine tyrosine (PYY) are secreted from IEC L-cells. Both IECs are distributed throughout the gastrointestinal tract and are targets for anti-diabetic therapies since GIP and GLP-1 directly stimulate insulin secretion. The secretion of these peptides has been extensively investigated and the current model of IEC sensing involves both raised intracellular Ca2+ and cAMP...