Sulfonylurea treatment outweighs insulin therapy in short-term metabolic control of patients with permanent neonatal diabetes mellitus due to activating mutations of the KCNJ11 (KIR6.2) gene

To the Editor, Activating missense mutations in the gene encoding potassium inwardly rectifying channel, subfamily J, member 11 (KCNJ11) represent the most common cause (40 to 64%, depending on populations) of permanent neonatal diabetes mellitus in patients diagnosed in the first 6 months of life [1, 2]. In addition, KCNJ11 activating mutations can lead to transient/relapsing neonatal diabetes [3, 4]. The KCNJ11 gene encodes the pore-forming subunit (also known as KIR6.2) of the pancreatic beta cell ATP-sensitive potassium channel (KATP), which exerts a pivotal role in glucose-regulated insulin release. In the beta cell, KIR6.2 forms a hetero-octameric complex (4:4) with the sulfonylurea receptor subtype 1 (SUR1); binding to SUR1 by sulfonylureas determines channel closure and insulin secretion [2]. In previously published cases, seven patients have been reported to respond well to the transfer from insulin to oral hypoglycaemic agents [4–8]. Here we report on the replacement of insulin with sulfonylureas in ten Italian children who have mutations in KCNJ11 (R50P, V59M [x4], K170R, R201C and R201H [x3]) and were followed in nine Diabetologia (2006) 49:2210–2213 DOI 10.1007/s00125-006-0329-x