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.

The blood glucose level is the amount of glucose in the blood. When blood glucose levels (also called blood sugar levels) drop too low, it's called hypoglycemia (pronounced: hi-po-gly-see-me-uh). Very low blood sugar levels can cause severe symptoms that need to be treated right away.

Low Blood Sugar Levels in People With Diabetes

People with diabetes can have low blood sugar levels because of the medicines they have to take to manage their diabetes. They may need a hormone called insulin or diabetes pills (or both) to help their bodies use the sugar in their blood. These medicines help take the sugar out of the blood and get it into the body's cells, which makes the level of sugar in the blood go down. But sometimes it's a tricky balancing act and blood sugar levels can get too low.

People with diabetes need to keep their blood sugars from getting too high or too low. Part of keeping blood sugar levels in a healthy range is having good timing, and balancing when and what they eat and when they exercise with when they take medicines.

Some things that can make low blood sugar levels more likely to happen are:

• skipping meals and snacks
• not eating enough food at a meal or snack
• exercising longer or harder than usual without eating some extra food
• getting too much insulin
• not timing the insulin doses properly with meals, snacks, and exercise

Also, certain things may increase how quickly insulin gets absorbed into the bloodstream and 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.

Other things that can cause insulin to be absorbed more quickly include injecting the shot into a muscle instead of the fatty layer under the skin and injecting the insulin into a part of the body most used in a particular sport (like injecting the leg right before soccer practice). All of these situations increase the chances that a person may get hypoglycemia.

Signs and Symptoms of Low Blood Sugar Levels

Different people may feel low blood sugar levels differently. People with low blood sugar may:

• feel hungry or have "hunger pains" in their stomach
• feel shaky or like they're trembling
• have a rapid heart rate
• feel sweaty or have cold, clammy skin
• have pale, gray skin color
• have a headache
• feel moody, cranky, or irritable
• feel drowsy, weak, or dizzy
• be unsteady or stagger when walking
• have blurred or double vision
• feel confused
• have seizures or convulsions
• lose consciousness (pass out)

If you have diabetes, try to remember how your body reacts when your blood sugar levels are low. It may help you figure out when you're having a low blood sugar level more quickly the next time.

Checking for Low Blood Sugar Levels

The warning signs of hypoglycemia are the body's natural response to 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, shaking, and having an increased heart rate are early signs of the adrenaline being released. If the hypoglycemia isn't treated, more severe symptoms may develop, including drowsiness, confusion, seizures, and loss of consciousness.

The only way to know for sure if you're having a low blood sugar level is to test. 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 you can't quickly check your blood sugar level, it's important to treat yourself for hypoglycemia immediately to prevent symptoms from getting worse.

Sometimes a person 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. The hormone adrenaline (mentioned above) is not just released when blood sugar drops too low — it's also released when blood sugar levels fall quickly when they're too high. If you're having a false reaction, you might actually have blood sugar levels in a healthy range but feel as if you have low blood sugar. Testing blood sugar levels before treating yourself for hypoglycemia can help you figure out if you're having a false reaction.

Some people with diabetes don't actually notice the typical signs of low blood sugar levels. For them it's even more important to check blood glucose levels often and take extra precautions to prevent low blood sugar (see our prevention tips below). If you're having trouble feeling the symptoms of low blood sugar, let your diabetes health care team know.

Treating Low Blood Sugar Levels

Your diabetes health care team will give you guidelines for treating low blood sugar levels, depending on your symptoms. If you can, try to test your blood sugar levels to make sure that your symptoms are because of hypoglycemia. If you can't test blood sugar immediately, don't delay in treating your symptoms — you can always check your blood sugar after you've taken steps to get your 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, you should take in sugar or sugary foods, which raise the blood sugar level quickly. Your health care team might suggest that you:

• Eat, drink, or take something that contains sugar that can get into the blood quickly. Your doctor may tell you to have really sugary foods or drinks (like regular soda, orange juice, or cake frosting) or might give you glucose tablets or gel to take — all of these can help to raise your blood sugar level fast, which is what you need to do when it's low.
• Wait about 10 minutes to let the sugar work.
• Recheck your blood sugar level with a glucose meter to see if blood sugar levels are back to normal.
• Get a glucagon shot (see below), if your symptoms are severe or get worse after you eat, drink, or take glucose.

Sometimes, blood sugar levels can get so low that you may not be awake enough to eat or drink something to get them back up. When this happens, you may need a glucagon shot.

Glucagon (pronounced: gloo-kuh-gon) is a hormone that helps raise blood sugar levels quickly. Your parents, teachers, and coaches should all know how to give glucagon shots in case of a low blood sugar emergency or at least know to call 911. Your doctor can prescribe a glucagon kit, which should be kept in a place where the people who are close to you can easily find it.

Also, you should always wear a medical identification bracelet or necklace and/or carry an ID that says you have diabetes. Then, if you are not feeling well, whoever's helping you — even if the person doesn't know you — will know to call for medical help. This medical identification also can also include your doctor's phone number or a parent's phone number.

Preventing Low Blood Sugar Levels

By knowing what causes low blood sugar levels and being prepared, you can lessen the chance that you'll have low blood sugar levels. But no matter how well they take care of themselves, people with diabetes will sometimes have low blood sugar levels.

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

• Eat all your meals and snacks on time and try not to skip any.
• Take the right amount of insulin.
• If you exercise longer or harder than usual, have an extra snack.
• Don't take a hot bath or shower right after an insulin shot.
• Stick to your diabetes management plan.
• Check your blood sugar levels regularly, so you can tell if your blood sugars are running too low and your treatment plan needs adjustment.
• Carry something containing sugar with you at all times and take it right away if you have symptoms. Don't wait to see if the symptoms will go away — they may get worse!

Alcohol and drugs can cause major problems with your blood sugar levels, so avoiding them is another way to prevent diabetes problems. Drinking can be particularly dangerous — even deadly — for people with diabetes because it messes up the body's ability to keep blood glucose in a normal range. This can cause a very rapid drop in blood glucose in people with diabetes. Drug or alcohol use is also dangerous because it may impair someone's ability to sense low blood sugar levels.

Learning how to recognize the signs of low blood sugar levels and get them back to normal is an important part of caring for diabetes. Keeping track of your blood sugar levels and recording lows when they occur will help you and your diabetes health care team keep your blood sugar levels in a healthy range.

Reviewed by: Steven Dowshen, MD
Date reviewed: January 2010