In short
Neonatal hyperglycaemia, or high blood sugar in newborn babies, is less common than low blood sugar but requires careful attention because it can increase the risk of serious health problems and even death in affected infants.
What is neonatal hyperglycaemia?
Neonatal hyperglycaemia is a condition where a newborn baby has unusually high levels of sugar (glucose) in their blood. This condition is defined as a blood glucose level greater than 150 milligrams per deciliter (mg/dL) or 8.3 millimoles per liter (mmol/L) when measured in serum (the liquid part of blood after clotting), or greater than 125 mg/dL (6.9 mmol/L) in whole blood, regardless of how many weeks the baby was in the womb or how old they are after birth.
Although high blood sugar in newborns is less common than low blood sugar, it is particularly important to address because it increases illness and death rates among newborn babies. The safe target range for blood glucose levels in newborns is generally 70 to 150 mg/dL.
What causes this condition?
The most common cause of neonatal hyperglycaemia is iatrogenic, meaning it is unintentionally caused by medical treatment. This typically happens when newborn babies, especially very small premature infants weighing less than 1.5 kilograms, receive too-rapid intravenous infusions of dextrose (a form of sugar) during their first few days of life.
Another important cause is physical stress on the baby's body. Situations that create stress include surgery, low oxygen levels, respiratory distress syndrome (a breathing disorder common in premature babies), or sepsis (a serious infection affecting the whole body). Fungal sepsis poses a particularly high risk for causing hyperglycaemia.
In premature infants, the body may not properly process proinsulin (a precursor to insulin) into active insulin, and the body's tissues may be relatively resistant to insulin's effects. These problems can lead to high blood sugar levels.
Other causes include transient neonatal diabetes mellitus, which is a rare, self-resolving form of diabetes that usually occurs in babies who are small for their gestational age. Treatment with corticosteroid medications (a type of anti-inflammatory drug) can also result in temporary high blood sugar.
Additional factors that can contribute to hyperglycaemia include delays in starting feeding, certain medications given to the mother or baby (such as diazoxide, dopamine, dobutamine, epinephrine, caffeine, or theophylline), and issues related to how nutrition is provided through intravenous lines.
Signs and symptoms
The symptoms and signs that appear in babies with neonatal hyperglycaemia are typically those of the underlying disorder causing the high blood sugar, rather than symptoms specific to the elevated glucose itself. This means that healthcare providers need to look at the baby's overall condition to understand what might be happening.
How is it diagnosed?
Doctors diagnose neonatal hyperglycaemia by testing the baby's blood glucose levels. This is done through serum glucose testing, where a small blood sample is taken and analyzed.
In addition to high blood glucose levels, laboratory tests may reveal other findings. These can include glycosuria (glucose present in the urine) and marked serum hyperosmolarity (an unusually high concentration of dissolved substances in the blood).
Treatment approaches
Treatment for neonatal hyperglycaemia depends on what is causing the high blood sugar. For cases caused by medical treatment (iatrogenic hyperglycaemia), the first step is to reduce either the concentration of dextrose in the intravenous fluids—for example, changing from a 10% solution to a 5% solution—or to reduce the rate at which the fluid is given to the baby.
If high blood sugar continues even when low dextrose infusion rates are used (such as 4 milligrams per kilogram per minute), this may indicate that the baby has a relative shortage of insulin or that their body is resistant to insulin's effects.
For other causes of hyperglycaemia, treatment involves using fast-acting insulin. One approach is to add fast-acting insulin to an intravenous infusion of 10% dextrose at a steady rate of 0.01 to 0.1 units per kilogram per hour, and then adjust the rate until glucose levels return to normal. Another method is to add insulin to a separate intravenous line given at the same time as the main fluid infusion, which allows doctors to adjust the insulin without changing the total amount of fluid the baby receives.
It is extremely important to monitor the baby's blood glucose levels carefully and adjust the insulin dose precisely, as responses to insulin can be unpredictable.
In cases of transient neonatal diabetes mellitus, healthcare providers carefully maintain glucose levels and hydration until the high blood sugar resolves on its own, which usually happens within a few weeks.
Any fluids or minerals (electrolytes) lost through increased urination due to high blood sugar should be replaced to keep the baby properly hydrated.
