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Diabetes: Low Blood Sugar (Hypoglycemia)

What is low blood sugar?

Blood sugar is considered to be dangerously low if it is less than 70 milligrams per deciliter (mg/dL), or 3.9 millimoles per liter (mmol/L). The medical term for low blood sugar is hypoglycemia. If you have diabetes, it is sometimes called an insulin reaction or insulin shock.

How does it occur?

Low blood sugar is usually a side effect of diabetes treatment. It can also result from other conditions, diseases, medicines, hormone or enzyme deficiencies, tumors.

If you have diabetes and you have too much insulin or other diabetes medicine in your blood, your blood sugar level will get too low. Some other things that can cause an abnormally low blood sugar levels when you have diabetes are:

  • exercising more than usual
  • skipping or delaying meals or snacks
  • having a meal or snack that is too small
  • not taking diabetes medicines at the right time
  • side effects of other medicines
  • drinking alcohol
  • diarrhea or vomiting.

Low blood sugar from these other causes is usually not as low and not as dangerous as low blood sugar caused by too much insulin or other diabetes medicine.

If you are using insulin, you may have low blood sugar because:

  • You have accidentally used too much or the wrong type of insulin.
  • Your insulin is no longer good because it has expired or was not stored properly.
  • You have an insulin pump that is not working properly.

What are the symptoms?

Low blood sugar can make you feel:

  • hungry
  • nervous
  • sweaty
  • shaky
  • lightheaded
  • dizzy
  • confused.

For some people, a blood sugar below 90 mg/dL (5 mmol/L) can make them feel like this. For others, it takes a lower blood sugar (below 70 mg/dL, or 3.9 mmol/L) to cause these symptoms.

You must watch your blood sugar level closely. Regular testing of your blood sugar, as recommended by your healthcare provider, may allow you to detect and treat low blood sugar before it causes serious symptoms. You may be able to prevent ever having low blood sugar.

Some high blood pressure medicines called beta blockers hide the symptoms of low blood sugar. If you are taking medicine for high blood pressure, ask your healthcare provider if the medicines you are taking could have this effect.

You should know the difference between the symptoms of low blood sugar (hypoglycemia) and high blood sugar (hyperglycemia). High blood sugar doesn't always cause symptoms, but when it does the symptoms may include blurry vision, extreme thirst, and a lot of urination.

How is it treated?

If you often have symptoms of low blood sugar, you should see your healthcare provider. Your provider can help you determine the cause. Your provider will also give you guidelines for treating low blood sugar when you are having symptoms.

When you see your provider, be sure to take your notebook or glucose meter with all of the results of your recent blood sugar checks. This helps your provider know whether you are on the right medicines and are taking the right dose at the right time of day. Without this record, it is harder for your provider to help you figure out the cause of your symptoms.

Here are some examples of guidelines your provider may give you:

  • If you have diabetes and you think your blood sugar may be too low, check it with your home glucose meter before treating yourself treatment for low blood sugar, if possible.
  • Always carry some form of sugar you can eat as soon as you have any symptoms of low blood sugar. The following amounts and types of foods will bring your blood sugar level up:
    • 3 to 4 glucose tablets
    • 1/2 cup (4 oz) fruit juice
    • 1/2 cup (4 oz) regular (not diet) soda (about half a can)
    • 8 ounces of skim milk
    • 1/4 to 1/3 cup of raisins
    • 5 to 7 pieces of hard candy like Lifesavers
    • a tube of glucose in gel form (such as InstaGel or MonGel)
    • 1 tablespoon of molasses, corn syrup, or honey.
  • If you still have symptoms 10 to 15 minutes after eating or drinking one of the foods listed above, you may need to eat or drink another portion.
  • If you are about to eat a meal, eat the fruit or drink the juice first and then eat the rest of your meal.
  • After 15 minutes, check your blood sugar again. If it is still lower than 70 milligrams per deciliter (mg/dL), take another serving of one of the foods on the list. Repeat these steps until your sugar is above 70 or until you feel better. You may need to eat a snack or meal soon after you feel better to keep your blood sugar from getting too low again.

The diabetes medicines Precose (acarbose) and Glyset (miglitol) keep your body from absorbing some types of sugar. If you have low blood sugar and you are taking these medicines, you must use glucose tablets or gel, or honey or fruit, to raise your blood sugar.

If you have diabetes, you need to know how to recognize and treat low blood sugar right away to bring it back up to a healthy range. Low blood sugar is a very serious condition and if you don't take action right away you could pass out, have a seizure, or even die. You should not go to bed until you have raised your sugar back into your normal range.

If your symptoms get worse despite treatment, call your healthcare provider or have a family member or friend call 911. Emergency treatment may include a shot of glucose or a medicine called glucagon to raise your blood sugar. You may need to go to the hospital to be treated with intravenous (IV) glucose. Being at the hospital will also allow your healthcare provider to watch your reaction to treatment, determine why you had severe hypoglycemia, and, if necessary, change your medicine dosages.

If you tend to have episodes of low blood sugar, talk with your healthcare provider about whether you should have a medicine called glucagon on hand. It can be given as a shot by a family member when you are having low blood sugar but are not alert enough to safely take some food or give yourself the shot. It makes your blood sugar rise quickly. Your family members should also know how to use your glucose meter to check your blood sugar when you are not able to. However, if you are unconscious, they should call 911 to get help on the way before trying to check your sugar and treat your low blood sugar.

How long will the effects last?

The effects of low blood sugar will continue and may even get worse until treatment brings your blood sugar level back to normal. It may take several minutes for the symptoms to go away after you start treatment. This may be a temporary problem while you and your healthcare provider are adjusting your medicine. If you are always prone to having low blood sugar, you may need to take special care for the rest of your life to keep your blood sugar at the proper level.

How can I take care of myself?

  • Keep your blood sugar in the normal range. Check your blood sugar level regularly according to your healthcare provider's recommendation and whenever you have any of the symptoms of low blood sugar. Know when to check your blood sugar and when to call for help. Ask your healthcare provider for guidelines to help you know when to call for help.
  • Carry sugar or hard candy to eat so if your blood sugar gets too low you can treat it right away.
  • Carry a medical ID (such as a card or bracelet) that says you have diabetes, in case of an emergency.
  • When your blood sugar is low, be careful not to drive or do any activity that requires good reflexes and your full attention. Driving with a low blood sugar is very dangerous, both for you and for others. The effect of a low blood sugar on your judgment, reflexes, and ability to react are similar to those of a person driving under the influence of alcohol. It's a good idea to check your sugar before you get in the driver's seat, especially on long trips. Always keep a quick source of sugar with you. Pull over to the side of the road right away if you begin to feel symptoms of low blood sugar and take your emergency sugar. Do not try to treat low blood sugar while you are driving.
  • If you are taking insulin, discuss with your healthcare provider whether you should carry the medicine glucagon with you at all times. A family member or friend can be taught how to give you a shot of glucagon if you become unconscious or unable to swallow liquids or food safely. After they give you the shot, they should call 911. The glucagon should raise your blood sugar enough for you to become conscious in a few minutes. Then, when you are awake enough, you can eat or drink something sweet, such as orange juice. If you have an episode of unconsciousness from low blood sugar, you need to see your provider to determine why you developed low blood sugar.
  • Call your healthcare provider if you notice that your blood sugar has been below 70 mg/dL and several rounds of eating or drinking 15 grams of carbohydrate have not helped it get higher. This could be a sign that you and your provider need to change your diabetes treatment plan.
  • If your symptoms get WORSE, call your healthcare provider RIGHT AWAY or have a family member or friend call 911.

How can I prevent low blood sugar?

  • Check your blood sugar regularly.
  • Know what causes low blood sugar.
  • Eat at regular mealtimes. Do not delay or skip meals and do not eat partial meals.
  • Take all medicines exactly as prescribed.
  • Check your blood sugar more often when you are exercising more or eating less, or when you are sick, according to your healthcare provider's recommendations.
  • Keep your follow-up appointments with your provider.
Developed by Phyllis G. Cooper, RN, MN, and RelayHealth.
Published by RelayHealth.
Last modified: 2011-05-23
Last reviewed: 2011-03-03
This content is reviewed periodically and is subject to change as new health information becomes available. The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional.
© 2011 RelayHealth and/or its affiliates. All rights reserved.
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