• We are sorry, but NCBI web applications do not support your browser and may not function properly. More information
Regular self-monitoring of glucose levels has not been proven to have benefits for people with type 2 diabetes who do not inject insulin. It is not known whether self-monitoring can help prevent diabetes-related complications in this group of people.

PubMed Health. A service of the National Library of Medicine, National Institutes of Health.

A.D.A.M. Medical Encyclopedia [Internet]. Atlanta (GA): A.D.A.M.; 2013.

A.D.A.M. Medical Encyclopedia [Internet].

Low blood sugar

Hypoglycemia; Insulin shock; Insulin reaction

Last reviewed: May 31, 2013.

Low blood sugar is a condition that occurs when the body's blood sugar (glucose) is too low.

Blood sugar below 70 mg/dL is considered low. Blood sugar at or below this level can be harmful.

The medical name of low blood sugar is hypoglycemia.

Causes

Insulin is a hormone made by the pancreas. Insulin is needed to move glucose into cells where it is used for energy. Without enough insulin, glucose builds up in the blood instead of going into the cells. This leads to symptoms of diabetes.

Low blood sugar occurs due to any of the following:

  • Your body's sugar (glucose) is used up too quickly
  • Glucose is released into the bloodstream too slowly
  • Too much insulin is released into the bloodstream

Low blood sugar is common in people with diabetes who are taking insulin or other medicines to control their diabetes.

Babies born to mothers with diabetes may have severe drops in blood sugar.

In people who do not have diabetes, low blood sugar may be caused by:

Symptoms

Symptoms you may have when your blood sugar gets too low include:

  • Double vision or blurry vision
  • Fast or pounding heartbeat
  • Feeling cranky or acting aggressive
  • Feeling nervous
  • Headache
  • Shaking or trembling
  • Sweating
  • Tingling or numbness of the skin
  • Tiredness or weakness
  • Trouble sleeping
  • Unclear thinking

Even if you do not have symptoms, your blood sugar could still be too low. You may not even know you have low blood sugar until you faint, have a seizure, or go into a coma.

Exams and Tests

If you check your blood sugar at home, the reading will be lower than 70 mg/dL on your glucose monitor.

At the hospital, you will likely have blood samples taken from your vein to:

  • Measure your blood sugar level
  • Diagnose the cause of your low blood sugar

Treatment

The goal of treatment is to correct your low blood sugar level.

If you have diabetes, it is likely your health care provider told you how to treat yourself for low blood sugar. Treatment can include drinking juice or eating food or glucose tablets. Or you may have been told to give yourself a shot of glucagon. This is a medicine that raises blood sugar.

If low blood sugar is caused by an insulinoma (insulin-releasing tumor), surgery to remove the tumor will be recommended.

Possible Complications

Severe low blood sugar is a medical emergency. It can cause seizures and brain damage. Severe low blood sugar that causes you to become unconscious is called insulin shock.

Severe low blood sugar may make it less likely for you to have symptoms that allow you to recognize another episode of low blood sugar.

When to Contact a Medical Professional

If signs of low blood sugar do not improve after you have eaten a snack that has sugar:

  • Get a ride to the emergency room - do not drive yourself
  • Or call a local emergency number (such as 911)

Get medical help right away for a person with diabetes or low blood sugar who:

  • Becomes less alert
  • Cannot be woken up

References

  1. American Diabetes Association. Standards of medical care in diabetes -- 2013. Diabetes Care. 2013;36 Suppl 1:S11-S66. [PMC free article: PMC3537269] [PubMed: 23264422]
  2. Cryer PE. Hypoglycemia. In: Melmed S, Polonsky KS, Larsen PR, Kronenberg HM. Williams Textbook of Endocrinology. 12th ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 34.

Review Date: 5/31/2013.

Reviewed by: Brent Wisse, MD, Associate Professor of Medicine, Division of Metabolism, Endocrinology & Nutrition, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Bethanne Black, and the A.D.A.M. Editorial team.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org). URAC's accreditation program is an independent audit to verify that A.D.A.M. follows rigorous standards of quality and accountability. A.D.A.M. is among the first to achieve this important distinction for online health information and services. Learn more about A.D.A.M.'s editorial policy, editorial process and privacy policy. A.D.A.M. is also a founding member of Hi-Ethics and subscribes to the principles of the Health on the Net Foundation (www.hon.ch).

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only — they do not constitute endorsementscof those other sites. © 1997–2011 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.

Copyright © 2013, A.D.A.M., Inc.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org). URAC's accreditation program is an independent audit to verify that A.D.A.M. follows rigorous standards of quality and accountability. A.D.A.M. is among the first to achieve this important distinction for online health information and services. Learn more about A.D.A.M.'s editorial policy, editorial process and privacy policy. A.D.A.M. is also a founding member of Hi-Ethics and subscribes to the principles of the Health on the Net Foundation (www.hon.ch).

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only — they do not constitute endorsementscof those other sites. © 1997–2011 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.

Copyright © 2013, A.D.A.M., Inc.

What works?

  • Diabetes: Recognizing the signs of low blood sugarDiabetes: Recognizing the signs of low blood sugar
    If blood sugar levels are too low, this is called hypoglycemia. Mild hypoglycemia usually has no severe consequences. But it is important to react early enough and eat or drink something, for example. Severe hypoglycemia can lead to loss of consciousness, so in certain situations medical help may be needed.
See all (163) ...

Figures

  • Food and insulin release.

PubMed Health Blog...

read all...

MedlinePlus.gov links to free, reliable, up-to-date health information from the National Institutes of Health (NIH) and other trusted health organizations.

Recent Activity

Your browsing activity is empty.

Activity recording is turned off.

Turn recording back on

See more...