Activating mutations in either the KCNJ11 or ABCC8 genes encoding the two subunits (Kir6.2 and SUR1, respectively) of the ATP-sensitive potassium (KATP) channel of the β-cell membrane, prevent insulin secretion in response to hyperglycaemia and can cause both PNDM and TNDM [26,27,28]. This evidence concerns the gene KCNJ11 and transient neonatal diabetes mellitus.