Oral Therapy in a Diabetic Patient With History of Infantile Hyperinsulinism

Hyperinsulinism is the most common cause of persistent hypoglycemia in early infancy (1). Loss of function mutation in HNF4A gene is an unusual cause of this disease (2). HNF4A protein is a homodimer nuclear transcription factor with 474 amino acids which plays a role in 22 identified pathways. Mutations in this gene cause deficiency in regulation of beta-cell development and nuclear receptors transcription pathways, associated with maturity onset diabetes of Young (MODY) and HNF4A-related hyperinsulinism (3, 4). Association of hyperinsulinemia in infancy and diabetes in adolescence has been reported only in patients with HNF4A mutations (4). We present a patient with hyperinsulinmia in infancy and diabetes in adolescence without HNF4A mutation and with good response to oral hypoglycemic agents. In infancy, this patient presented with persistent hyperinsulinemic hypoglycemia. He was on oral diazoxide until 3 years of age when this drug was tapered and discontinued. Genetic study was not performed at that time due to limitation of facilities. After that time, his blood sugar was normal until 15 years of age when he presented with diabetes mellitus. Starting HbA1c was 9.5%. In addition, fasting triglyceride level and cholesterol level was 66 mg/dL and 168 mg/dL, respectively. Other routine laboratory studies were within the normal range. Pancreas anatomy was also normal in ultrasonography.