No matter what we're doing, even during sleep, our brains depend on glucose to function. Glucose is a sugar that comes from food, and it's also formed and stored inside the body. It's the main source of energy for the body's cells and is carried to them 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 in someone with diabetes are considered low when they fall below the target range. A blood sugar level slightly lower than the target range won't necessarily cause symptoms, but repeated occurrences might require a change in the treatment plan to help avoid hypoglycemia symptoms.

The diabetes health care team will determine a child's target blood sugar levels depending upon factors like the child's age, ability to recognize hypoglycemia symptoms, and the goals of the diabetes treatment plan.

Causes of Low Blood Sugar Levels

Low blood sugar levels are fairly common in people with diabetes. A major goal of treatment is to keep 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 medications usually help keep blood sugar levels in a healthy range, but in certain situations, might cause them to drop too low.

Hypoglycemia can happen at any time in people taking blood sugar-lowering medicines, but is more likely to occur if someone:

• skips or delays meals or snacks or doesn't eat as much carbohydrate-containing food as expected when the person took the diabetes medicine. This is particularly common in kids who develop an illness (such as a stomach virus) that causes loss of 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

Other situations in which low blood sugar levels can occur include:

• low blood sugar levels that occur during sleep, known as nocturnal hypoglycemia
• low blood sugar levels that occur several hours after exercise, known as delayed postexercise hypoglycemia
• low blood sugar levels 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. Drug or alcohol use can pose additional risks because it may impair someone'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 may increase how quickly insulin is absorbed into the bloodstream and 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 also can 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 cause the insulin to be absorbed more quickly. All of these situations increase the likelihood of hypoglycemia.

Signs and Symptoms of Low Blood Sugar

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

Warning signs of low blood sugar include:

• extreme hunger (some kids 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

And kids who have nocturnal hypoglycemia may have bouts of crying or nightmares, night sweats (with damp sheets and/or pajamas), and waking 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. Paleness, 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, 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 the levels are not actually low. This is a called a false reaction. Adrenaline also can be released when blood sugar levels fall rapidly from a high level to a normal level. Testing blood sugar levels before giving treatment for hypoglycemia can help you identify false reactions.

Also, some kids may learn to fake symptoms of low blood sugar to get a sugary treat or avoid something unpleasant. Again, checking the blood sugar level can confirm the presence of hypoglycemia.

It's important to discuss the signs and symptoms of low blood sugar with your child. Even younger kids who can't verbalize symptoms should learn how to alert their parents when they don't feel well. This will help kids make the connection between how they feel and the need for treatment. Kids also should know to seek out an adult for assistance.

Some people with diabetes don't experience or sense the typical early warning symptoms of low blood sugar, a condition known as hypoglycemic unawareness. They're 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 the diabetes health care team know.

Treating Low Blood Sugar Levels

The diabetes health care team will provide specific guidelines for treating your child's hypoglycemia, depending on the severity of the symptoms.

If it's convenient, before treating your child for hypoglycemia, test the blood sugar levels to confirm that the symptoms are due to hypoglycemia. If blood sugar can't be checked immediately, don't delay treating your child's symptoms — you can always do a test after getting the blood sugar back into the normal range.

When blood sugar levels are low, the goal is to get them back up quickly. To do that, give your child 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 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 that case, 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 not delayed 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.

Check in with the doctor after any severe low blood sugar reaction requiring glucagon treatment, as this could indicate a need to adjust the diabetes management plan to help prevent future hypoglycemia episodes.

When possible, adult family members and your child's caregivers and school staff should know:

• the signs of hypoglycemia
• when and how to give glucagon shots
• when to seek emergency medical attention

Your doctor can prescribe a glucagon kit, which should 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 decrease the frequency of low blood sugar levels 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.

Additional tips to help 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 blood glucose levels before and during exercise and make sure your child 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 keeps something containing sugar with him or her at all times and takes it right away if symptoms of low blood sugar appear.

But no matter how careful parents and children may be, kids with diabetes at some point will have episodes of low blood sugar. So they should always wear and/or carry some sort of medical identification (like a bracelet or necklace). Besides 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 2010