Neonatal Hypoglycemia and Hyperglycemia

Glucose homeostasis in the newborn period is complex and essential for normal neonatal development. Glucose is the primary metabolic fuel for the neonatal brain. Maintaining normal glucose levels in the peripheral circulation and across the blood-brain barrier is essential for normal neurologic function and development. The perinatal period represents a transition from fetal metabolism of delivered maternal glucose to active regulation of glucose and energy levels through glycolysis, gluconeogenesis, and lipolysis. During this period, healthy neonates may have glucose levels considered low for older children. Still, it is also a period where infants with underlying abnormalities of glucose regulation are at high risk for severe symptomatic hypoglycemia. Neonatal hypoglycemia can be due to abnormalities in insulin, growth hormone, or cortisol secretion, with therapy dictated by the underlying abnormality. Additionally, inborn errors of metabolism or other genetic conditions can also present with neonatal hypoglycemia. Infants with hyperinsulinemic hypoglycemia are at particular risk for brain injury due to the simultaneous suppression of alternate metabolic fuels for the brain. Hyperglycemia is usually transient in neonates and can be managed with supportive care and insulin infusion. However, some infants will have diabetes beyond 3 months of age, which is likely to have a genetic cause. Patients with neonatal diabetes due to pathogenic variants affecting the KATP channel can be treated with oral sulfonylurea in place of insulin therapy.