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 need immediate medical 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 might not cause symptoms, but repeated low levels could require a change in the treatment plan to help avoid problems.
The diabetes health care team will find a child's target blood sugar levels based on things 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 diabetes care 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. These medicines usually help keep blood sugar levels in a healthy range, but in certain situations, might make them drop too low.
Hypoglycemia can happen at any time in people taking blood sugar-lowering medicines, but is more likely if someone:
skips or delays meals or snacks or doesn't eat as much carbohydrate-containing food as expected when taking the diabetes medicine. This is 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
A low blood glucose level also can happen:
during sleep, known as nocturnal hypoglycemia
several hours after exercise, known as delayed postexercise hypoglycemia
after someone drinks alcohol or uses drugs. Alcohol hurts the body's ability to keep blood glucose in a normal range, which can cause a sudden drop in blood sugar. Drug or alcohol use also can make it hard for someone to sense low blood sugar levels. Talk to your child or teen about the health risks of alcohol and drug use.
Certain conditions also can increase how quickly insulin is absorbed into the bloodstream and make hypoglycemia more likely. 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 in the leg right before soccer practice) can make the insulin be absorbed more quickly. All of these situations increase the likelihood of hypoglycemia.
The signs and symptoms of low blood sugar can vary depending on the person and how quickly the level falls. Also, problems other than hypoglycemia or diabetes can cause similar symptoms.
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
a pale, gray skin color
moodiness or crankiness/irritability
unsteadiness/staggering when walking
blurred or double vision
seizures or convulsions
loss of consciousness
Kids who have nocturnal hypoglycemia may have bouts of crying, nightmares, or night sweats (with damp sheets and/or pajamas), and might 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. Paleness, sweating, shakiness, and increased heart rate are early warning signs of this adrenaline release.
More severe symptoms — such as confusion, drowsiness, seizures, and loss of consciousness — may happen if the hypoglycemia isn't treated and the brain doesn't get enough glucose to work 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 your child for hypoglycemia immediately to prevent symptoms from getting worse.
Sometimes a child with diabetes may have symptoms of low blood sugar, 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 when and how to find an adult for help.
Some people with diabetes don't have or can't sense the early warning signs of low blood sugar, a condition known as hypoglycemic unawareness. They're at greater risk for not recognizing the need to get treatment for hypoglycemia promptly. This could lead to more serious symptoms, such as loss of consciousness or seizures, as their blood sugar falls.
The diabetes health care team will give you clear guidelines about how to treat hypoglycemia, depending on the severity of the symptoms.
If it's convenient, test the blood sugar levels before treating your child 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 glucose level quickly. In general, 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, symptoms will stop about 10 minutes after your child takes sugar.
rechecking your child's blood sugar to make sure 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 get worse after your child is given sugar by mouth
For more severe cases of hypoglycemia in which seizures or loss of consciousness happen, 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. Call 911 if your care team has advised you to do so at this point.
Call the doctor after any severe low blood sugar reaction requiring glucagon treatment — it could be a sign that the diabetes management plan needs to be changed 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 get emergency medical care
Your doctor can prescribe a glucagon kit, which should be kept where you and your child's caregivers can easily find it.
By knowing what causes low blood sugar levels and being prepared, you and your child can make them less likely and help prevent severe symptoms.
Remember: You can't turn off the action of insulin once it's been injected. So to avoid low blood sugar episodes, insulin doses need to be matched to your child's needs each day — taking meals, exercise, and other things into consideration.
More 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 due to hypoglycemia.
Your child shouldn'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.
Your child should keep something containing sugar with him or her at all times and take it right away if symptoms of low blood sugar appear.
No matter how careful parents and children are, 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 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: Mauri Carakushansky, MD and Jennifer L. Seekford, ARNP