Transition from insulin to sulfonylurea in a child with diabetes due to a mutation in KCNJ11 encoding Kir6.2-initial and long-term response to sulfonylurea therapy

Mutations in the KCNJ11 gene encoding the adenosine triphosphate (ATP)-sensitive potassium channel (K_ATP) subunit Kir6.2 are the most frequent cause of diabetes in infancy. Sulfonylurea (SU) treatment restores insulin secretion in patients with KCNJ11 mutations. We report a 9-year-old boy who presented at the age of three months with diabetic ketoacidosis. Results Sequencing of the KCNJ11 gene revealed an R201H mutation. Therefore, he was transferred from insulin to oral SU therapy. He required a high-threshold dose before insulin could be discontinued. After transition, a subsequent dose reduction was necessary to avoid hypoglycemia. Improved sustained metabolic control without complications was achieved on a low SU maintenance dose twice daily over 36 months. SU therapy is safe for patients with diabetes due to KCNJ11 mutations. The mechanism of a threshold dose and the twice-daily requirement needs further attention.