What are signs of hypoglycemia in newborns?

Glucose screening is recommended for infants in the following categories who are at increased risk for pathological hypoglycemia:

• Born to mothers with gestational diabetes or diabetes mellitus
• Large for gestational age (LGA)
  
• Small for gestational age (SGA)
  
• Premature (<37 weeks gestation)

Checking at least one glucose level is also recommended for infants with clinical signs consistent with hypoglycemia:

• Tremors, jitteriness, irritability
• Exaggerated Moro reflex
• High pitched cry
• Lethargy, listlessness, hypotonia
• Cyanosis, apnea, tachypnea
• Hypothermia, temperature instability
• Poor suck, refusal to feed

Transiently low blood glucose levels are physiologic in the newborn and the distinction between hypoglycemia and euglycemia is not always clear.  Point of care (using a reagent strip) glucose testing is primarily used for screening due to the rapidity of results, but consistency between point of care results and the more accurate laboratory value is less than ideal.  This variation is greatest at low glucose concentrations, the levels frequently seen in neonates.  For this reason, at least one laboratory glucose value should be obtained when point of care results might lead to interventions such as IV placement and/or separation from parents.

Asymptomatic hypoglycemia is common among infants with risk factors and has historically been treated by ensuring the infant is getting adequate nutrition, which typically involves supplementation (banked breast milk or formula) as well as assisting mother to maximize colostrum expression in the hours after birth.  In recent years many hospitals have started using oral dextrose gel to treat asymptomatic hypoglycemia as well.

Symptomatic hypoglycemia is less common.  Prompt intervention is necessary in these cases, with consideration of immediate IV dextrose in the infant who is not well appearing.  Symptoms such as suppressible tremors (jitteriness) and sleepiness occur in many infants who do not have hypoglycemia as part of normal newborn transition, so often these are “mild symptoms” of hypoglycemia and less invasive treatment is typically tried prior to IV dextrose.  The method for correcting hypoglycemia should be determined by the clinical status of the infant and considerations for how soon the intervention will normalize the glucose level.  If an infant overall appears well, attempts can be made to correct hypoglycemia by feeding the infant and/or giving dextrose gel.  Glucose absorption from rubbing dextrose gel on a baby’s buccal mucosa has similar response time to administering IV dextrose.  Additional evaluation for other underlying disorders should also be considered for the symptomatic infant with hypoglycemia, unless symptoms resolve promptly with glucose correction.

Within the first 4 hours of life:

Any glucose level less than 25 mg/dL in a baby with severe symptoms requires immediate IV fluid therapy.  In an asymptomatic baby, an initial glucose level (within the first 4 hours of life) of less than 25 mg/dL should prompt treatment with dextrose gel and an immediate feeding, with another glucose check in an hour. If the subsequent test is still <25 mg/dL, IV dextrose or repeating a dose of gel should be considered, depending on the clinical status of the infant. If the subsequent test is >25 but <35 mg/dL, the infant should again be given dextrose gel, fed and retested, although IV fluid therapy may be indicated for some patients in this group.

Between 4 - 24 hours of life:

Any glucose level less than 45 mg/dL in a baby with severe symptoms requires immediate IV fluid therapy.  In an asymptomatic baby, a glucose level of less than 45 mg/dL should prompt dextrose gel with immediate feeding, and another glucose check in an hour.  If the subsequent test is still <45 mg/dL, further attempts to correct the glucose with up to 3 total doses of categorized as dextrose gel and continued supplemental feeding should be attempted.  Infants who have persistently low glucoses (<45 mg/dL) should be considered for IV dextrose treatment.

Hypoglycemia can be associated with adverse neurologic outcomes, but in many cases these infants also have other risk factors or pathology.  Scientific evidence has not established a connection between isolated low glucose levels in asymptomatic infants and neurologic injury.

Newborn, Committee on Fetus and. “Postnatal Glucose Homeostasis in Late-Preterm and Term Infants.” Pediatrics 127, no. 3 (March 1, 2011): 575–79. https://doi.org/10.1542/peds.2010-3851.

Rozance, Paul J., and William W. Hay. “New Approaches to Management of Neonatal Hypoglycemia.” Maternal Health, Neonatology and Perinatology 2, no. 1 (May 10, 2016): 3. https://doi.org/10.1186/s40748-016-0031-z.

“Oral Dextrose Gel for the Treatment of Hypoglycaemia in Newborn Infants - Weston, PJ - 2016 | Cochrane Library.” Accessed May 27, 2020. https://www-cochranelibrary-com.laneproxy.stanford.edu/cdsr/doi/10.1002/14651858.CD011027.pub2/full.

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