Familial permanent neonatal diabetes with KCNJ11 mutation and the response to glyburide therapy--a three-year follow-up.

We describe 3 years follow-up of glyburide therapy in a child with permanent neonatal diabetes mellitus (PND) born to a 19 year-old mother with congenital diabetes mellitus. Genetic analysis identified a KCNJ11 mutation (R201H) in both the child and her mother. After 2 years of insulin therapy, the patient was switched to oral glyburide. After initial stabilization, glyburide therapy resulted in a marked decrease in glucose excursions in comparison to insulin. The patient had 3-10 episodes of hypoglycemia per week, including a total of eight episodes resulting in seizures, while on insulin. In contrast, no severe hypoglycemia was reported on glyburide. The patient's basal C-peptide was undetectable on insulin therapy (< 166 pmol/l) but was easily detectable on glyburide (189-761 pmol/l). The range of HbA1c improved significantly from 8-12% on insulin to 4.7-6% on glyburide. The frequency of glucose monitoring was gradually decreased from 4-8 times to 2-3 times a day on oral glyburide. This report confirms the superiority of sulfonylurea therapy in the treatment of PND with Kir6.2 mutations and shows sustained improved glycemic control over a 3-year follow-up period. Genetic exploration in other family members with diabetes might provide further insight into the nature of familial neonatal diabetes.