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Diabetes: Low Blood Sugar (Hypoglycemia)

What is low blood sugar?

Hypoglycemia means that your blood glucose (sugar) level is abnormally low. If your blood sugar is too low and not treated right away, you could pass out, have a seizure, go into a coma, or even die. For most adults, a low blood sugar is less than 70 mg/dL. However, each person is different and your healthcare provider may recommend that you treat low blood sugar at a different level.

When you have diabetes, it’s important to watch your blood sugar level closely. This is especially important if you are newly diagnosed and are learning how to control your blood sugar. 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.

The medical term for low blood sugar is hypoglycemia. If you are taking insulin, very low blood sugar is sometimes called an insulin reaction or insulin shock.

What is the cause?

Low blood sugar is a possible side effect of diabetes treatment. When you have diabetes, low blood sugar can be caused by too much insulin or from other diabetes medicine. If you are using insulin, it may happen because:

  • You have accidentally used too much or the wrong type of insulin.
  • You have an insulin pump that is not attached properly or not working.

Some other things that can cause abnormally low blood sugar when you have diabetes are:

  • Exercising more than usual
  • Skipping or delaying meals or snacks
  • Having a meal or snack that is too small
  • Dieting to lose weight
  • Not taking diabetes medicines at the right time
  • Side effects of other medicines
  • Drinking alcohol
  • Diarrhea or vomiting
  • Problems caused by tumors or lack of hormones
  • Severe kidney or liver disease
  • Taking a bath or shower or soaking in a hot tub soon after taking a shot of insulin (blood vessels in the skin get larger from the hot water and cause insulin to be absorbed more quickly)

What are the symptoms?

It is important to recognize low blood sugar as soon as possible, before it gets dangerously low and causes a severe reaction.

Symptoms may include:

  • Shakiness
  • Hunger
  • Nervousness, or anxiety
  • Grumpiness or irritability
  • Sweating or chills
  • Lightheadedness
  • Nausea
  • Headache
  • Fast pulse
  • Confusion (feeling or looking dazed)

For some people, a blood sugar below 90 mg/dL can cause these symptoms. For others, symptoms may not start until the blood sugar level is below 70 mg/dL. If you don’t feel “right,” check your blood sugar.

If low blood sugar happens during the night, you may sleep through it or you may wake up with sweating, a headache, a fast heart rate, or feeling foggy headed. If you wake up with any of these signs of low blood sugar, test and treat your blood sugar right away. Also think about what was different the previous day (like extra exercise, extra insulin, or less food). This will help you learn how to keep it from happening again. Keep a record of these reactions. It may help to test your blood sugar right before you go to bed and to have a snack if your blood sugar is low.

Some high blood pressure medicines called beta blockers can 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.

How is it treated?

Insulin reactions happen quickly and should be treated at once. The general rule is to give some kind of sugar as fast as possible.

Your provider will give you guidelines for treating low blood sugar when you are having symptoms. Here are some examples of guidelines your provider may give you:

  • If you think your blood sugar may be too low, check it with your home glucose meter before treating yourself, if possible.
  • Always carry some form of sugar that you can eat as soon as you have any symptoms of low blood sugar. Each of the following amounts and types of food are about 15 to 20 grams of glucose or simple carbohydrates and should bring the blood sugar level up quickly:
    • 3 to 4 glucose tablets
    • 1/2 cup (4 oz) fruit juice
    • 1/2 cup (4 oz) regular (not diet) soda
    • 8 ounces of skim milk
    • 2 tablespoons of raisins (about a palm full)
    • 5 to 7 pieces of hard candy like Lifesavers
    • A tube of glucose in gel form
    • 1 tablespoon of molasses, corn syrup, or honey

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

  • If you still have symptoms 10 to 15 minutes after eating or drinking one of these foods, 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’s still low, take another serving of one of the foods on the list. Repeat these steps until your blood sugar is in the range recommended by your healthcare provider (usually above 70) or until you feel better. You may need to eat a protein snack (like peanuts, peanut butter, or cheese) or a meal soon after you feel better to keep your blood sugar from getting too low again.
  • You should rest at least 10 minutes after eating and repeat the blood sugar test to make sure it in the right range before returning to normal activity

If your symptoms get worse despite treatment, call your healthcare provider or have a family member or friend call 911. If you pass out, someone should call 911 to get help on the way before checking for or treating low blood sugar. Emergency treatment may include medicine to raise your blood sugar. You may need to go to the hospital to be treated with IV glucose.

Your healthcare provider may tell you to keep glucagon on hand. It makes your blood sugar rise quickly. It can be given as a shot by a family member when you are having low blood sugar and are not alert enough to safely take some food or give yourself the shot. Your family members should also know how to use your glucose meter to check your blood sugar when you are not able to.

If you often have symptoms of low blood sugar, see your healthcare provider. When you see your provider, be sure to take your records of all of the results of your recent blood sugar checks. This helps your provider know if you are on the right medicines and are taking the right dose at the right times of day. Without this record, it’s harder for your provider to help you figure out the cause of your symptoms and to prescribe the best treatment plan and schedule for you.

How can I take care of myself?

Follow the full course of treatment prescribed by your healthcare provider. In addition:

  • Take your glucose meter and equipment with you whenever you leave the house.
  • Know when to check your blood sugar and when to call for help.
  • Check your blood sugar more often when you are exercising more or eating less, or when you are sick, according to your provider’s instructions.
  • Keep some sugar or hard candy always with you so if your blood sugar gets too low you can treat it right away.
  • Recheck your blood sugar 15 minutes after treatment for low blood sugar to make sure it goes back up (especially at bedtime or during the night).
  • Carry a medical ID (such as a card or bracelet) that says you have diabetes.
  • When your blood sugar is low, be careful not to drive or do anything that requires clear thinking and good reflexes. The effect of a low blood sugar on your judgment, reflexes, and ability to react are similar to those of a person under the influence of alcohol.

Ask your provider:

  • How and when you will hear your test results
  • If there are activities you should avoid and when you can return to your normal activities
  • How to take care of yourself at home
  • What symptoms or problems you should watch for and what to do if you have them

Make sure you know when you should come back for a checkup. Keep all appointments for provider visits or tests.

How can I help prevent low blood sugar?

You can help prevent low blood sugar if you:

  • Check your blood sugar regularly.
  • Learn your symptoms of low blood sugar so that you can treat it right away.
  • Know what causes low blood sugar.
  • Eat at regular mealtimes. Don’t delay or skip meals and don’t 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 and take your glucose meter or sugar log to show your provider at your checkups.
Developed by RelayHealth.
Adult Advisor 2015.1 published by RelayHealth.
Last modified: 2015-02-10
Last reviewed: 2015-01-08
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.
Copyright ©1986-2015 McKesson Corporation and/or one of its subsidiaries. All rights reserved.

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