PATHOGENESIS
When the plasma glucose concentration falls below 60 mg/dL (3.3 mmol/L) in children who do not have PHHI, only small amounts of insulin are secreted. In children who have PHHI, the normal relationship between plasma glucose concentration and insulin secretion is disturbed, so that insulin is released even during periods of hypoglycemia. This disturbance of the normal relationship between glucose concentration and insulin secretion can be caused by a variety of genetic mutations, as discussed below, most commonly by mutations causing abnormal function or regulation of the ATP-dependent potassium (KATP) channel of the pancreatic beta cells