Low Blood Sugar (Hypoglycemia) Learning Center

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Low Blood Sugar (Hypoglycemia)

What Is Low Blood Sugar (Hypoglycemia)?

Also known as hypoglycemia, low blood sugar can be a dangerous condition. People often complain about low blood sugar. However, serious hypoglycemia is rare in adults and children over the age of 10 who are not suffering from diabetes. Diabetes is a chronic disease that causes your blood glucose or blood sugar to be high.

Your blood sugar is a measurement of the amount of glucose in your body. Glucose is a sugar that comes from food. Mainly found in carbohydrates, it gives your body energy. Without enough glucose, your body cannot perform its normal functions.

Your blood sugar is considered low when it drops below 70 mg/dL. Immediate treatment for such low blood sugar levels is important. You can either eat food or take glucose tablets.

If you have diabetes, you are more likely to have episodes of hypoglycemia or low blood sugar. Diabetes affects your body’s ability to regulate your blood sugar. You may not be able to make insulin, the hormone that allows your cells to Your body may also have a negative reaction to the insulin used to prevent high blood sugar. This can lead to low blood sugar. Diabetics have to carefully monitor their insulin and blood sugar to keep things in balance.

Recognizing the Signs of Low Blood Sugar

Low blood sugar symptoms can occur suddenly. They include:

  • blurry vision
  • rapid heartbeat
  • sudden mood changes
  • sudden nervousness
  • unexplained fatigue
  • pale skin
  • headache
  • hunger
  • shaking
  • sweating
  • difficulty sleeping
  • skin tingling
  • trouble thinking clearly or concentrating

Your blood sugar can drop so quickly you may not even have warning symptoms. When this occurs, you can faint, experience a seizure, or even go into a coma.

Very low blood sugar is a medical emergency. If you know that someone is diabetic and they are experiencing these symptoms, get them to eat something. It is more important to treat a low blood sugar than to be concerned about a short-term blood sugar spike.

Serious Complications From Spells of Low Blood Sugar

Severely low blood sugar levels can be life threatening. You can experience seizures and nervous system damage. Immediate treatment is critical. It is important to learn to recognize your symptoms and treat them fast.

Because you can lose consciousness, don’t try to drive to a medical provider when your blood sugar is too low. Instead, eat something to raise your glucose. Then call an ambulance or get a ride.

What Causes Low Blood Sugar?

Low blood sugar can occur for a number of reasons. It is usually a side effect of diabetes treatment.

Diabetes and Low Blood Sugar

Diabetes affects your body’s ability to use insulin. Think of insulin as the key that unlocks your cells, letting glucose in for energy. People with diabetes use a variety of treatments to help their bodies use the glucose in their blood. One very important treatment is insulin injections.

If you inject too much insulin, your blood sugar may drop too low. People also sometimes inject insulin when planning to eat a big meal, but then they do not eat enough. Additionally, excess physical activity without eating enough can cause a blood sugar drop.

Other Causes of Low Blood Sugar

You don’t have to have diabetes to experience low blood sugar. Some other causes of low blood sugar include:

  • certain medications, such as quinine
  • drinking too much alcohol
  • medical conditions, such as hepatitis or kidney disorders
  • a tumor that produces excess insulin
  • endocrine disorders, such as adrenal gland deficiency

A condition known as reactive hypoglycemia can cause your blood sugar to drop too low after eating. This is common if you have undergone gastric bypass or other weight-loss surgery.

How Is Low Blood Sugar Diagnosed?

Blood sugar levels are measured with a simple blood test. If you have diabetes, you are accustomed to testing your blood glucose several times a day to determine whether you are controlling your diabetes. You prick your finger and then place the blood on a test strip. This strip is inserted into a special machine. If you suspect that your blood sugar is low, you can just test it as you would normally.

If you do not have a blood sugar testing machine on hand, your symptoms may be enough to diagnose low blood sugar. Do not rely solely on this self-diagnosis. If you have symptoms of low blood sugar they can and usually do get worse if untreated. You should see a health professional. That is the only way to figure out what is causing your symptoms.

Treating Low Blood Sugar Levels

When your blood sugar levels are too low, eating something with carbohydrates can help.

If you have diabetes, try to keep high-carbohydrate snacks on hand. The American Diabetes Associations recommend that your snack has at least 15 to 20 grams of carbohydrates (National Institutes of Health). For example:

  • a half-cup of juice or regular soda
  • 1 tablespoon of honey
  • 4 or 5 saltine crackers
  • 5 or 6 pieces of hard candy
  • 1 tablespoon of sugar

You also can take glucose tablets. These are available without prescription.


You must strike the right balance between eating enough and not eating too much. You also don’t want your blood sugar to get too high. Eat something and wait about 15 minutes. Then check your blood sugar again. If you do not feel better, eat another snack. If your blood sugar won’t go up at all, seek immediate medical help.

If you have lost consciousness due to low blood sugar, a medical provider may be able to give you a glucagon or glucose injection. These can quickly raise your blood sugar.

Tips to Prevent Future Episodes of Low Blood Sugar

Regularly checking your blood sugar levels can help you intervene before your blood sugar drops dangerously low. Talk to your doctor about how often you should check your blood sugar. You may need to check it at different times or more often.

If you have had low-blood sugar episodes in the past, you may wish to check your blood sugar levels before driving (or operating other types of machinery). Have a snack before leaving your home or if your blood sugar levels are less than 100 mg/dL.

Sometimes you may feel low blood sugar symptoms coming on, but your blood sugar testing machine is not handy. If this is the case, the American Diabetes Association recommends treating your blood sugar as if it is too low. Remember, a low blood sugar is more dangerous than a brief episode of high blood sugar.

You may also want to talk with friends and family about how to care for you if your blood sugar drops too low. They should learn to recognize low blood sugar symptoms and know the importance of calling 911 if you lose consciousness.

Wearing a medical identification bracelet can help emergency responders care for you if you need emergency attention.

Content licensed from:

Written by: Rachel Nall
Updated on Feb 15, 2013
Medically reviewed by Brenda B. Spriggs, MD, MPH, FACP

This feature is for informational purposes only and should not be used to replace the care and information received from your health care provider. Please consult a health care professional with any health concerns you may have.
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