Abstract

Congenital hyperinsulinism is the most common cause of persistent hypoglycemia in the newborn period. This case demonstrates an infant who was diagnosed with hyperinsulinism and responded to diazoxide treatment. Persistence of hypoglycemia led to genetic testing, which identified a novel de novo mutation in hepatocyte nuclear factor 4 alpha as the cause of the hyperinsulinism. Patients with this form of hyperinsulinism are noted to have variable clinical courses in terms of length of treatment needed with diazoxide. This gene mutation is also associated with the eventual development of maturity-onset diabetes of the young, so continued close clinical follow-up will be needed, even after the hypoglycemia resolves.