The ATP-dependent potassium (K_ATP) channels of pancreatic beta cells react to increased ATP by closing. This results in the opening of voltage-regulated calcium channels and insulin release. A K_ATP channel consists of four inner (Kir6.2) subunits and four outer units that constitute the beta cell sulphonylurea receptor, SUR1. Kir 6.2 is encoded by the gene KCNJ11 and SUR1 by the gene ABCC8. Activating (gain-of-function) mutations in these genes should, and do, cause diabetes and inactivating (loss-of-function) mutations, insulin hypersecretion and hypoglycaemia.

Neonatal diabetes affects about one in 100 000 infants. …