Improved diabetic control during oral sulfonylurea treatment in two children with permanent neonatal diabetes mellitus.

Permanent neonatal diabetes mellitus (PND), defined as diabetes diagnosed in the first 6 months of age and requiring life-long insulin therapy, is a rare disorder of unknown etiology. Activating mutations of the KCNJ11 gene, which encodes the Kir6.2 subunit of the ATP-dependent potassium channel in beta-cells, have been found to cause 30-58% of cases of PND. Sulfonylurea treatment in theses patients reduces or eliminates the need for exogenous insulin. We report two Taiwanese boys who were diagnosed with PND at 1 and 4.5 months of age. They had been treated with exogenous insulin for 6 and 15 years, respectively. In September 2006, they were both found to have a KCNJ11 mutation (valine-to-methionine at codon 59; V59M). Glibenclamide successfully increased the basal C-peptide level, lowered HbA(1c), and reduced blood sugar excursions. In one patient, the insulin dose was reduced to 0.2 U/kg/day, and the other was able to discontinue insulin altogether. These two cases from Taiwan add to the experience with similar mutations reported in Caucasians.