A healthy baby's body most often has very careful control of blood sugar level. Insulin is the main hormone in the body that regulates blood sugar. Sick babies may have poor insulin function or low amounts. This causes poor control of the blood sugar.

There can be specific causes of ineffective or low insulin. Causes may include infection, liver problems, hormone problems, and some medicines. Rarely, babies may actually have diabetes, and therefore have a low insulin level that results in high blood sugar.

Babies with hyperglycemia often have no symptoms.

Sometimes, babies with high blood sugar will produce large amounts of urine and become dehydrated. High blood sugar may be a sign that the baby has added stress on the body due to problems such as an infection or heart failure.

A blood test will be done to check the baby's blood sugar level. This can be done with a heel or finger stick at the bedside or in a health care provider's office or lab.

There are most often no long-term effects from a temporary high blood sugar level unless the baby has diabetes.