Low Blood Sugar in Newborns: Causes, Signs and Long-Term Effects

Glucose, or blood sugar, is crucial to brain development as it is the main source of energy for the brain. Neonatal hypoglycemia is a condition in which a baby’s blood sugar falls dangerously low within a few days of birth. These low glucose levels can impair the growth process and cause brain cells to die. Neonatal hypoglycemia is one of the most common neonatal metabolic issues, and is easily treated.When a baby transitions to life outside the mother’s womb, blood glucose levels naturally drop during the first two hours after delivery (2). However, an infant with neonatal hypoglycemia (NH) experiences a more dramatic and prolonged drop in blood sugar than a healthy infant would. In utero, the fetus is usually able to obtain steady glucose levels from the mother through the placenta. After birth, the infant takes in glucose from breastmilk or formula, as well as producing it in the liver. A stable level of glucose is important for organ function in a newborn baby, and the brain uses glucose almost exclusively for energy metabolism and development (3).

Jump to:

Neonatal Hypoglycemia

Neonatal Hypoglycemia is one of the most common metabolic problems in babies, and severe NH is one of the leading causes of neonatal brain injury. Neonatal hypoglycemia is not difficult to recognize, and usually  is very easily treated. However, untreated NH can lead to serious consequences because an infant’s developing brain tissue depends on a steady supply of glucose as its main source of fuel. When a baby’s brain doesn’t receive a sufficient amount of glucose, the cells in the brain begin to die, and this can lead to permanent brain damage (3).

Risk factors for neonatal hypoglycemia

Some medical conditions that can cause NH are listed below (this is not a complete list) (3) : :

  • Babies who are unusually small or large for gestational age (see our pages on intrauterine growth restriction [IUGR] and macrosomia)
  • Preterm babies: may have poor nutrient reserves and immature hormone systems that can increase their risk
  • Babies who were born to diabetic mothers
  • Babies who have a history of asphyxia (HIE) or stress in the womb
  • Babies with low thyroid hormone levels (hypothyroidism)
  • Babies who have certain rare genetic disorders

Causes of neonatal hypoglycemia

The causes of neonatal hypoglycemia include the following (2):

  • An excess of insulin in the baby’s blood: Insulin is a hormone that decreases the amount of glucose in the blood. When a baby has an excess of insulin, one condition  is called persistent hyperinsulinemic hypoglycemia of infancy (PHHI).
  • Hypoxic ischemic encephalopathy (HIE)
  • Limited storage of glycogen: Before glucose is broken down into its simple form, it is stored in the form of glycogen.  Decreased glycogen storage can happen as a result of prematurity or intrauterine growth restriction (IUGR), and can cause hypoglycemia.
  • Increased glucose use: A baby may need to utilize more glucose than usual due to the following medical conditions:  
    • Hyperthermia (high body temperature from infection, medication, or head injury)
    • Polycythemia (abnormally high red blood cell mass, which can be caused by oxygen deprivation)
    • Sepsis (a bacterial infection in the bloodstream)
    • Growth hormone deficiency
  • Decreased glycogenolysis: This is a decreased breakdown of glycogen into glucose.
  • Decreased gluconeogenesis: This is a decreased creation of glucose caused by a problem with a metabolic pathway.
  • Depleted glycogen stores:  This can be caused by the following:
    • Asphyxia-perinatal stress (baby deprived of oxygen for so long during birth that damage occurs, usually to the brain).
    • Starvation

Long-term effects of neonatal hypoglycemia

If neonatal hypoglycemia goes undiagnosed and/or untreated for too long, there is a chance for long-term injury. Some of these injuries include (2):

Signs and symptoms of neonatal hypoglycemia

In some cases, infants with low blood sugar may not even show symptoms. Routine blood tests are done following birth to check blood sugar levels. If signs and symptoms do surface, they may include the following (3):

  • Bluish-colored skin (cyanosis) or pale skin
  • Breathing problems, such as rapid breathing (tachypnea), pauses in breathing (apnea), or a grunting sound
  • Irritability or listlessness
  • Loose or floppy muscles (hypotonia)
  • Vomiting or poor feeding
  • Weak or high pitched cry
  • Tremors, shakiness, sweating, or seizures

Transient and persistent neonatal hypoglycemia

There are two different types of neonatal hypoglycemia, transient (short-term) and persistent (long-term). Babies who have transient NH typically have a deficiency of glycogen stores at birth. This is common in babies that are born premature, who are small for gestational age, or experienced birth asphyxia. Transient NH babies also may experience hyperinsulinism, which occurs most often in babies born to diabetic mothers (2).

Neonatal hypoglycemia can also occur if an IV infusion of glucose is interrupted; for example, if the umbilical catheter is incorrectly positioned or the baby has sepsis. If the baby experiences NH due to an error of medication administration, this is medical malpractice.

Diagnosis and treatment of neonatal hypoglycemia

When a baby shows clinical signs of having low blood glucose or the baby is known to be at risk for neonatal hypoglycemia, a blood glucose test must be done immediately. This test should be done within minutes of any presented symptoms by sending some of the baby’s blood to the lab for analysis. If the baby has low blood sugar, then their glucose concentration should be retested every three to six hours within the first 24 to 48 hours of life (2).   Because NH can result in brain injury if not treated properly, it is important to use aggressive therapy that includes the use of a parenteral glucose (dextrose) to increase blood glucose levels in children exhibiting symptoms (1). Dextrose is typically administered through an IV and the levels are monitored and adjusted until the blood glucose level in the baby is at an acceptable concentration. If needed, treatment will be continued for a few hours or days to a week, or until the baby can maintain normal glucose levels. Babies who were born early, have an infection, or were born at a low weight may need to be treated for a longer period of time.

General treatments for neonatal hypoglycemia

If IV dextrose isn’t an option for a baby with NH, glucagon can be used as a treatment and administered subcutaneously or intramuscularly (1). Glucagon can be used to treat babies who experience severe hypoglycemia and may not have dextrose available to them. Babies who have experienced NH and are not being treated with dextrose or glucagon should be fed within the first hour of life. These feedings should be done at two to three hour intervals, and blood glucose concentrations should be monitored frequently within 20 to 30 minutes after being fed.  Babies who are breastfed may need supplemental formula until the mother is able to produce enough breast milk (1).

Early diagnosis and treatment of neonatal hypoglycemia is crucial; the severity of the problems that can arise if neonatal hypoglycemia is left untreated highlights this point. Testing for hypoglycemia is simple, and if the baby had any risk factors for hypoglycemia and was not tested properly, the medical staff was negligent.  The medical staff also acted negligently if the baby had hypoglycemia and this condition was untreated or not treated properly. If the baby suffered brain damage or an injury as a result of these negligent acts, it is medical malpractice.

To begin your free case review, please contact our team in any of the following ways.

Free Case Review | Available 24/7 | No Fee Until We Win

Phone (toll-free): 866-738-1783

Press the Live Chat button on your browser

Complete Our Online Contact Form


  1. Rozance, P. J., MD. (n.d.). Management and outcome of neonatal hypoglycemia. Retrieved from https://www.uptodate.com/contents/management-and-outcome-of-neonatal-hypoglycemia?search=neonatal hypoglycemia&source=search_result&selectedTitle=2~54&usage_type=default&display_rank=2
  2. Rozance, P.J., MD. (n.d.) Pathogenesis, screening, and diagnosis of neonatal hypoglycemia. Retrieved from https://www.uptodate.com/contents/pathogenesis-screening-and-diagnosis-of-neonatal-hypoglycemia?search=neonatal%20hypoglycemia&source=search_result&selectedTitle=1~73&usage_type=default&display_rank=1
  3. McGowan, J. E. (1999, July 01). Neonatal Hypoglycemia. Retrieved from http://pedsinreview.aappublications.org/content/20/7/e6
  4. Congenital Hyperinsulinism. (n.d.). Retrieved from https://congenitalhi.org/congenital-hyperinsulinism/