ATP-sensitive potassium (K ) channels play a key role in mediating glucose-stimulated insulin secretion by coupling metabolic signals to ?-cell membrane potential. Loss of K channel function due to mutations in ABCC8 or KCNJ11, genes encoding the sulfonylurea receptor 1 (SUR1) or the inwardly rectifying potassium channel Kir6.2, respectively, results in congenital hyperinsulinism. Many SUR1 mutations prevent trafficking of channel proteins from the endoplasmic reticulum to the cell surface.