Neonatal hyperglycemia is defined as whole blood glucose levels exceeding 7.0 mmol/L (125 mg/dL) or serum glucose levels exceeding 8.40 mmol/L (150 mg/dL).
Etiology and Pathogenesis
Immature Glucose Regulation
The tolerance to glucose varies significantly among newborns. Lower gestational age and lower birth weight are associated with poorer glucose tolerance. Extremely low birth weight infants are prone to hyperglycemia even at a glucose infusion rate of 4–6 mg/(kg·min). Additionally, neonatal pancreatic β-cell function is underdeveloped, resulting in a sluggish response to hyperglycemia. The reduced insulin reactivity to glucose loads, combined with relative insulin resistance, causes an imbalance between hepatic glucose production and insulin output. This is a major contributing factor to neonatal hyperglycemia, particularly in extremely low birth weight infants.
Stress-Related Factors
In critical conditions such as asphyxia, severe infections, or trauma, levels of catecholamines, cortisol, and glucagon in the blood may rise significantly. These hormones enhance gluconeogenesis, leading to hyperglycemia.
Iatrogenic Causes
Hyperglycemia can occur after the infusion of highly concentrated glucose solutions, especially when administered too rapidly. Certain medications, including epinephrine, corticosteroids, aminophylline, caffeine, and phenytoin, also contribute to elevated glucose levels.
Neonatal Diabetes
This condition may present as:
- Transient Diabetes (also known as pseudodiabetes): Approximately one-third of affected neonates have a family history of diabetes. It is more common in infants small for gestational age.
- True Diabetes: Rare in newborns and believed to have a genetic basis.
Clinical Manifestations
Mild cases may lack symptoms. Newborns exhibiting significant or prolonged hyperglycemia may develop hyperosmolar hyperglycemia syndrome or hyperosmolar diuresis, resulting in dehydration, irritability, excessive thirst, polyuria, or even intracranial hemorrhage. Neonatal diabetes may present with positive results for glucosuria and ketonuria, which can be either positive or negative.
Prevention and Treatment
For preterm infants, especially those with extremely low birth weight, glucose infusion rates should be limited to ≤5–6 mg/(kg·min), with blood glucose levels monitored frequently. Adjustments to glucose infusion rates should be based on these measurements. Mild and transient hyperglycemia (lasting 24–48 hours) can often be corrected by reducing the glucose infusion rate, alongside treating the underlying condition and addressing dehydration and electrolyte imbalances. For cases where hyperglycemia is difficult to control and fasting blood glucose levels exceed 14 mmol/L, insulin therapy may be initiated. Insulin infusion typically begins at 0.01 U/(kg·h) and may gradually increase to 0.05–0.1 U/(kg·h). Blood glucose levels should be monitored every 30 minutes during insulin administration to prevent hypoglycemia. Insulin therapy is discontinued once blood glucose levels normalize.