What is the management of hypoglycemia (low blood sugar) in newborns?

Management of Neonatal Hypoglycemia

Intravenous glucose infusion should be initiated as soon as practical after identifying hypoglycemia, with the goal of maintaining blood glucose above 2.5 mmol/L (45 mg/dL) to prevent neurologic injury. 1, 2

Definition and Intervention Thresholds

Hypoglycemia in newborns is defined as blood glucose below 2.5 mmol/L (45 mg/dL), but intervention thresholds vary based on severity and clinical presentation 2, 3:

Immediate intervention is mandatory for:

• Any single measurement <1 mmol/L (18 mg/dL) 2, 3
• Blood glucose <2 mmol/L (36 mg/dL) that remains below this value at the next measurement 2, 3
• Any single measurement <2.5 mmol/L (45 mg/dL) in a newborn with abnormal clinical signs 2, 3

The rationale for aggressive intervention is clear: repetitive and prolonged hypoglycemia ≤2.5 mmol/L has been associated with impaired motor and cognitive development, particularly in preterm infants 2, 3. While some studies show no differences at 15 years after recurrent low glucose levels, the risk of harm during critical developmental periods justifies early aggressive management 3.

Screening Protocol for High-Risk Populations

Screen all infants with the following risk factors 2, 3:

• Premature birth 2, 3
• Low birth weight 2, 3
• Perinatal asphyxia 2, 3
• Infants of diabetic mothers 4, 5
• Small for gestational age or intrauterine growth restriction 5

Blood gas analyzers with glucose modules provide the best combination of quick results and accuracy for measurements in newborns 2, 6. Handheld glucose meters have significant accuracy concerns due to interference from high hemoglobin and bilirubin levels, which are common in neonates 2, 6.

Treatment Algorithm

For Asymptomatic Hypoglycemia:

• Supervised breastfeeding may be an initial treatment option for asymptomatic hypoglycemia in otherwise healthy term infants 7
• Oral dextrose gel can be used to augment early breastfeeding and prevent recurrent low glucose concentrations 8, 9
• Monitor prefeed glucose concentrations closely 8

For Symptomatic Hypoglycemia or Severe Values:

Symptomatic hypoglycemia should always be treated with continuous infusion of parenteral dextrose 7. This is non-negotiable, as symptoms indicate the brain is already experiencing metabolic stress 4, 8.

Glucose infusion rate guidelines 2:

• Start with 4-6 mg/kg/min and titrate upward as needed 2
• Carbohydrate intake should typically be increased stepwise to 10 mg/kg/min (14.4 g/kg/day) over the first 2-3 days 2
• Parenteral carbohydrate intake should preferably not exceed 12 mg/kg/min (17.3 g/kg/day) in preterm infants 2
• In term newborns, the minimum should be 2.5 mg/kg/min (3.6 g/kg/day) 2

Neonates requiring dextrose infusion rates above 12 mg/kg/min should be investigated for a definite cause of hypoglycemia, such as hyperinsulinemia or metabolic defects 7. This threshold indicates persistent hypoglycemia that is not simply transitional and requires endocrine evaluation 8.

Management of Hypoglycemic Seizures

If seizures occur, this constitutes a neonatal emergency 6, 4:

During active seizure 6:

• Place the newborn on their side in the recovery position to reduce aspiration risk 6
• Clear the area around the infant to prevent injury 6
• Do NOT place anything in the mouth or attempt oral glucose, liquids, or medications 6
• Do NOT restrain the seizing infant 6
• Maintain airway patency and provide high-flow oxygen 6
• Call for emergency medical help immediately 6

Treatment 6:

• Intravenous glucose is the primary treatment for newborns with active seizures or altered consciousness, since oral administration is contraindicated 6

Post-seizure monitoring 6:

• Monitor hourly capillary glucose, heart rate, respiratory rate, blood pressure, and neurologic status 6
• Repeat laboratory tests (electrolytes, blood glucose, blood gases) every 2-4 hours 6
• Provide oral carbohydrates once the infant is awake and able to swallow safely 6
• If the newborn does not return to baseline within 5-10 minutes after seizure stops, emergency medical intervention is required 6

Avoiding Hyperglycemia During Treatment

While treating hypoglycemia, vigilance is needed to avoid iatrogenic hyperglycemia 1. The use of protocols for blood glucose management may avoid both hypoglycemia and hyperglycemia, and prevent large swings in blood glucose concentration that have also been associated with harm 1.

Hyperglycemia thresholds requiring intervention 2:

• Avoid hyperglycemia >8 mmol/L (145 mg/dL) in neonatal ICU patients, as it is associated with increased morbidity and mortality 2
• Repetitive blood glucose levels >10 mmol/L (180 mg/dL) should be treated with insulin therapy, but only after reasonable adjustment of glucose infusion rate has been insufficient 2

Common Pitfalls

Measurement errors: Handheld glucose meters are unreliable in neonates due to high hemoglobin and bilirubin interference 2, 6. Always confirm low values with blood gas analyzer measurements before making treatment decisions 2, 6.

Delayed feeding: Early and continued breastfeeding is protective 8, 9. Delays in establishing feeding increase hypoglycemia risk 8.

Inadequate follow-up: Infants treated for hypoglycemia require close monitoring even after discharge, as recurrence can occur 9. Persistent hypoglycemia beyond 72 hours (the transitional phase) requires investigation for endocrine or metabolic disorders 9.

Underestimating severity: Severely low, prolonged, or recurrent low glucose concentrations, especially in infants with marked symptoms such as seizures, flaccid hypotonia with apnea, and coma, are clearly associated with permanent brain damage 8. Aggressive screening and treatment is recommended to prevent poor neurodevelopmental outcomes 7.