What Are Healthy Glucose Levels in Children?

The sugar glucose normally functions as the exclusive fuel for your child's brain and a primary energy source for muscles and other body tissues. As in adults, a child's body tightly regulates blood glucose to ensure the level does not rise too high after eating or fall too low between meals.

Healthy glucose levels in children mirror those of adults. (Image: Rawpixel/iStock/GettyImages)

In healthy children, blood glucose levels mirror those of adults after the first few days of life. Feeding your child a well-balanced diet and providing plenty of opportunities for physical activity will help ensure healthy glucose levels as your child grows and develops.


While in the womb, glucose is supplied to the fetus from the mother's bloodstream. In the first few hours to days after birth, a baby's glucose typically drops initially and then increases as the liver starts producing the sugar and the infant begins to feed.

In a healthy full-term infant, the blood glucose normally ranges from approximately 40 to 150 milligrams per deciliter (mg/dL) for during the first 3 to 4 days — a broader range than for older infants and children.

Infants, Children and Adolescents

By the end of the first week of life, a healthy baby is typically feeding regularly and all of the hormones and metabolic process necessary for glucose regulation are fully functioning. As a result, healthy glucose levels in infants, children and adolescents mirror those of adults.

In both children and adults, glucose levels vary depending on how long it has been since the last meal or snack. A healthy fasting glucose level — meaning 8 hours or longer since the last caloric intake — is 70 to 99 mg/dL. A healthy random glucose level, regardless of when the last meal or snack was, is 70 to 139 mg/dL. The highest levels typically occur 1 to 2 hours after eating.

Low Levels

Even healthy children can occasionally experience a transient low blood glucose, or hypoglycemia. This is most likely in children younger than age 6 and usually develops after a prolonged period of not eating. Unlike older children and adult, toddlers and preschoolers have a limited capacity to store glucose.

Additionally, young children utilize more glucose per pound of body weight than older children and adults. For these reasons, young children can only tolerate about 12 hours or less without eating before their blood sugar falls to a lower-than-normal level. Common symptoms include irritability, excessive sweating, cool skin and possibly vomiting.

Fortunately, a low glucose level due to not eating usually responds rapidly to a carbohydrate-rich snack, such as raisins or fruit juice. If your young child hasn't eaten for 12 hours due to stomach upset, call your doctor.

High Levels

Prediabetes and diabetes are the foremost concerns in a child with a high glucose level. Type 1 diabetes is the most common form of diabetes among children. Lack of production of the glucose-lowering hormone insulin causes increased blood sugar levels. Common signs and symptoms include increased hunger, thirst and urination. Weight loss, weakness and fatigue are also common.

Once rare in children, the incidence of type 2 diabetes (T2DM) has increased along with the rate of overweight and obesity. T2DM is most often diagnosed in adolescents and occurs due to insulin resistance, meaning the body tissues fail to respond normally to the glucose-lowering effects of insulin.

Prediabetes refers to increased blood glucose caused by insulin resistance, but the levels are not high enough to warrant a diagnosis of full-blown T2DM. Most children and adolescents with prediabetes or T2DM do not experience obvious symptoms and are diagnosed by blood tests to screen for the conditions.

Next Steps

If you have concerns about your child's glucose levels, talk with your healthcare provider. This is particularly important if your child has risk factors for prediabetes or T2DM, including:

  • Overweight or obesity
  • Close relatives with T2DM
  • Native American, African, Latino, Asian or Pacific Islander ethnicity
  • Mother has diabetes or had gestational diabetes during pregnancy
  • Child had low birth weight
  • Child has high blood pressure, abnormal blood fat levels or polycystic ovary syndrome
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