No matter what we're doing - even when we're sleeping - our brains depend on glucose to function. Glucose is a sugar that comes from the foods we eat, and it's also formed and stored inside the body. It's the main source of energy for the cells of our body, and it's carried to each cell through the bloodstream.

When blood glucose levels (also called blood sugar levels) drop too low, it's called hypoglycemia. Very low blood sugar levels can cause severe symptoms that require immediate treatment.

Blood sugar levels are considered low when they fall below your child's target range. This doesn't necessarily mean that a blood sugar level slightly lower than the target range will cause symptoms in your child, but having a pattern of blood sugar levels below the target range may indicate a need for a change in your child's treatment plan to help avoid hypoglycemia symptoms.

Your child's diabetes health care team will let you know what your child's target blood sugar levels are, which will vary based on factors like your child's age, ability to recognize hypoglycemia symptoms, and the goals of his or her diabetes treatment plan.

Causes of Low Blood Sugar Levels in Someone With Diabetes

Low blood sugar levels are fairly common in people with diabetes. A major goal of treatment in diabetes is to keep blood sugar levels from getting or staying too high to prevent both short- and long-term health problems. To do this, people with diabetes may use insulin and/or pills, depending on the type of diabetes they have and other factors. These medicines generally help keep the blood sugar level in a healthy range. But in certain situations, the medicines a person takes to manage his or her diabetes may cause the person's blood sugar level to drop too low.

Hypoglycemia can happen at any time in a person with diabetes who takes blood sugar-lowering medicines, but it's more likely to occur if a person with diabetes:

  • skips or delays meals or snacks or doesn't eat as much carbohydrate-containing food as was expected when the person took his or her dose of diabetes medicine. This is particularly likely to occur in children when they develop an illness (such as a stomach virus) that involves loss or appetite, nausea, or vomiting.
  • takes too much insulin, takes the wrong type of insulin, or takes insulin at the wrong time.
  • exercises more than usual without eating additional snacks or adjusting the dosage of diabetes medicines to help prevent drops in blood sugar level.

There are a few other situations in which low blood sugar levels in kids and teens who have diabetes occur:

  • Low blood sugar levels that occur when your child is sleeping. Doctors call this nocturnal hypoglycemia.
  • Low blood sugar levels that occur several hours after exercise. Doctors call this delayed postexercise hypoglycemia.
  • Low blood sugar levels that occur after drinking alcohol or using drugs. Alcohol impairs the body's ability to keep blood glucose in a normal range, which can cause an abrupt drop in blood sugar in people with diabetes. Drug or alcohol use can pose additional risks for kids with diabetes because it may impair a person's ability to sense low blood sugar levels. Talk to your child or teen about the health risks associated with alcohol and drug use.

In addition, certain conditions that may increase how quickly insulin gets absorbed into the bloodstream can make hypoglycemia more likely to occur. For example, taking a hot shower or bath right after having an insulin injection increases blood flow through the blood vessels in the skin, which can cause the insulin to be absorbed more quickly than usual. Insulin can also be absorbed more quickly when it's injected into a muscle instead of into the fatty layer under the skin. And giving a shot in a part of the body most used in a particular sport (like injecting the leg right before soccer practice) can also cause the insulin to be absorbed more quickly. All of these situations increase the chances that hypoglycemia will occur.

Signs and Symptoms of Low Blood Sugar

The signs and symptoms of low blood sugar can vary from child to child. The actual blood glucose level that triggers the symptoms differs depending on the person and how rapidly the blood sugar level falls. It's also important to remember that most of these symptoms can also be caused by problems unrelated to hypoglycemia or diabetes.

Warning signs of low blood sugar include:

  • extreme hunger (some children complain of a gnawing stomachache or "hunger pain")
  • shakiness or tremors
  • rapid heart rate
  • cold sweat
  • ashen skin color (a pale, gray skin color)
  • headache
  • moodiness or crankiness/irritability
  • drowsiness
  • weakness
  • dizziness
  • unsteadiness/staggering when walking
  • blurred or double vision
  • confusion
  • seizures or convulsions
  • loss of consciousness

In addition, children who have nocturnal hypoglycemia may experience bouts of crying or nightmares, night sweats (with damp sheets and/or pajamas), or wake up groggy or with a headache.

Checking for Low Blood Sugar Levels

When blood sugar levels fall too low, the body releases the hormone adrenaline, which helps get stored glucose into the bloodstream quickly. Becoming pale, sweating, shakiness, and increased heart rate are early warning signs of adrenaline release that comes from hypoglycemia. If the hypoglycemia isn't treated, more severe symptoms such as confusion, drowsiness, seizures, and loss of consciousness may develop as the brain doesn't receive enough glucose to function properly.

The only way to know for sure if your child has low blood sugar levels is to test them. Blood sugar levels can be tested with a glucose meter, which is a computerized device that measures and displays the amount of glucose in a blood sample. However, if the situation makes it impossible or inconvenient to quickly check the blood sugar, it's important to treat the child for hypoglycemia immediately to prevent symptoms from worsening.

Sometimes a child with diabetes may have symptoms of low blood sugar levels, but blood sugar levels are not actually low. This is a called a false reaction. Adrenaline can also be released when blood sugar levels fall rapidly from a high level to a normal level. Testing blood sugar levels before giving your child treatment for hypoglycemia can help you identify false reactions.

Also, some children may learn to fake symptoms of low blood sugar to get a sugary treat or avoid something unpleasant. In this situation, checking a blood sugar level will confirm the presence of hypoglycemia.

It's important to discuss the signs and symptoms of low blood sugar with your child. Younger children may not know how to verbalize symptoms, so you should talk to your child about how he or she feels when he or she has a low blood sugar level. Doing so will help your child make the connection between how he or she is feeling and the need for treatment. You should also make sure your child knows to seek out an adult for assistance.

Some people with diabetes don't actually experience or sense the typical early warning symptoms of low blood sugar, a condition known as hypoglycemic unawareness. These people are at greater risk for failing to recognize and get treatment for hypoglycemia promptly, possibly resulting in more serious symptoms such as loss of consciousness or seizures as their blood sugar falls.

If you think your child is having trouble sensing low blood sugar, be sure to let your child's diabetes health care team know.

Treating Low Blood Sugar Levels

Your child's diabetes health care team will give you specific guidelines for treating your child's hypoglycemia, depending on the severity of your child's symptoms. In general - when it's convenient - before treating your child for hypoglycemia, you can test his or her blood sugar levels to confirm that the symptoms are due to hypoglycemia. But if the blood sugar can't be tested immediately, don't delay treating your child's symptoms - you can always check the blood sugar after you've taken steps to get your child's blood sugar back up into the normal range.

When blood sugar levels are low, the goal is to get them back up quickly. To do that, your child should take in sugar or sugary foods that raise the blood sugar levels quickly. In general, the treatment for hypoglycemia involves:

  • having your child eat or drink a form of glucose that works fast, like regular soda, orange juice, or cake frosting or having your child take special tablets or gels that contain glucose. Generally, it will take approximately 10 minutes after taking the sugar for your child's symptoms to disappear.
  • rechecking your child's blood sugar levels to make sure that that the level is no longer low and giving your child food to help prevent the blood sugar from dropping again.
  • giving glucagon (see below), if your child's symptoms are severe or worsen after being given sugar by mouth.

For more severe cases of hypoglycemia in which seizures or loss of consciousness occur, giving sugar by mouth may be very difficult or even dangerous. In such a situation, a glucagon injection should be given.

Glucagon is a hormone that helps raise blood sugar levels quickly. Treatment with glucagon should be given as soon as severe hypoglycemia is suspected and shouldn't be delayed by first trying to call a doctor or ambulance. After receiving glucagon, a child should wake up within about 10 to 15 minutes and be able to take sugar or food by mouth to help prevent the blood sugar from falling again. If your child doesn't respond to the glucagon injection, call for emergency medical attention. It's also a good idea to check with the doctor after any severe low blood sugar reaction requiring glucagon treatment, as there may be a need to adjust the child's diabetes management plan to help prevent additional severe hypoglycemia episodes.

If possible, adult family members and your child's caregivers and school staff should learn how to identify signs of hypoglycemia and should be instructed on when and how to give glucagon shots and when to seek emergency medical attention. Your child's doctor can prescribe a glucagon kit, which should always be kept where you and your child's caregivers can easily find it.

Preventing Low Blood Sugar Levels

By knowing what causes low blood sugar levels and being prepared, you and your child can help decrease the frequency with which low blood sugar levels occur and help prevent severe symptoms. Remember: You can't turn off the action of insulin once it's been injected, so to reduce the likelihood of low blood sugar episodes, insulin doses need to be properly matched to your child's needs each day - taking meals, exercise, and other factors into consideration.

Here are some additional tips to help you and your child avoid low blood sugar levels:

  • Give your child the correct dose and type of insulin at the right time in the appropriate injection site.
  • Check your child's blood sugar regularly and whenever necessary to confirm that symptoms are being caused by hypoglycemia.
  • Make sure your child doesn't take baths or hot showers right after an insulin shot.
  • Check your child's blood glucose levels before and during exercise and make sure he or she eats snacks as needed to keep or bring blood sugar levels into target range.
  • Make sure your child follows the suggested timing of meals, injections, and exercise, based on the diabetes management plan.
  • Make sure your child carries something containing sugar with him or her at all times and takes it right away if he or she has symptoms of low blood sugar.

But no matter how diligent parents and children may be, kids with diabetes will at some point experience episodes of low blood sugar. So all kids and teens with diabetes should wear and/or carry some sort of medical identification (like a bracelet or necklace) at all times. In addition to identifying your child as having diabetes, this identification can provide emergency contact information.

If you have any questions about how to prevent or treat low blood sugar levels, call your child's doctor or diabetes health care team.

Reviewed by: Steven Dowshen, MD
Date reviewed: October 2007

Related Sites

National Institute of Diabetes and Digestive and Kidney Diseases
American Diabetes Association (ADA)
Children With Diabetes
Joslin Diabetes Center On-Line Library
Juvenile Diabetes Research Foundation International (JDRF)

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