Neonatal diabetes is more than just a paediatric problem: 57 years of diabetes from a Kir6.2 mutation

Permanent neonatal diabetes (PNDM) usually presents within the first three months of life and requires insulin treatment from diagnosis. Heterozygous activating mutations in the KCNJ11 gene which encodes Kir6.2 have recently been identified as a common cause of PNDM. There is a genotype‐phenotype relationship with some mutations also resulting in developmental delay, muscle weakness and epilepsy. Sulphonylureas can be effective in treating diabetes caused by Kir6.2 mutations by restoring insulin secretion from the beta cells. Many patients can discontinue insulin and achieve good glycaemic control with sulphonylureas.

We describe the case of a 57‐year‐old man diagnosed with diabetes at five months of age and treated with insulin from diagnosis. He had delayed motor and intellectual development and has significant learning difficulties. Molecular genetic analysis identified a Kir6.2 mutation (V59M) that has been reported in other patients with diabetes, developmental delay and/or muscle weakness. Transfer to sulphonylureas was not considered appropriate in this case as effective treatment could not be guaranteed and was considered too disruptive for this patient who valued routine. This case highlights the possibility of other adults in diabetes clinics with Kir6.2 who are yet to be identified and raises awareness of the likelihood of Kir6.2 in those diagnosed with diabetes before six months of age. Copyright © 2005 John Wiley & Sons, Ltd.