Hypoglycemia (Low Blood Sugar) in People Without Diabetes

Search Knowledgebase

Topic Contents

Hypoglycemia (Low Blood Sugar) in People Without Diabetes

Topic Overview

Is this topic for you?

Hypoglycemia, or low blood sugar, is most common in people who have diabetes. If you have already been diagnosed with diabetes and need more information about low blood sugar, see the topics:

What causes low blood sugar?

Your body uses hormones to keep your blood sugar in a normal range. But a long-term health problem that needs treatment can cause blood sugar to drop too low.

Hypoglycemia is most commonly a complication of diabetes treatment (diabetic hypoglycemia). You can develop hypoglycemia by taking too much insulin or other diabetes medicines.

Hypoglycemia may have other causes such as medicines, alcohol, stomach surgery, metabolic problems, and diseases of the pancreas, liver, kidneys, or adrenal glands.

What are the symptoms?

The symptoms can be different depending on how low your blood sugar level drops.

  • Mild hypoglycemia can make you feel hungry or like you want to vomit. You could also feel jittery or nervous. Your heart may beat fast. You may sweat. Or your skin might turn cold and clammy.
  • Moderate hypoglycemia often makes people feel short-tempered, nervous, afraid, or confused. Your vision may blur. You could also feel unsteady or have trouble walking.
  • Severe hypoglycemia can cause you to pass out. You could have seizures. It could even cause a coma or death.

If you've had hypoglycemia during the night, you may wake up tired or with a headache. And you may have nightmares. Or you may sweat so much during the night that your pajamas or sheets are damp when you wake up.

How is hypoglycemia diagnosed?

To diagnose hypoglycemia, your doctor will do a physical examination and ask you questions about your health. You will need tests to check your blood sugar levels. Mostly, these are done while you are fasting. The time that you have to keep from eating can vary and may be 24 hours or more. Or you may learn how to take your own blood sugar when you notice symptoms that may be related to low sugar levels. Your doctor will also ask you about any medicines you take and whether you have recently lost or gained weight.

If a blood test shows that you have low blood sugar and you do not have diabetes, and if you have symptoms that go away after you eat a snack or drink with sugar in it, you probably have hypoglycemia.

Many people have symptoms of low blood sugar that is related to other medical problems. It is important to let your doctor do the tests to find out if your blood sugar is low enough to cause a problem.

How is it treated?

If you have symptoms of low blood sugar, you need to eat or drink something with sugar in it. For example, you could eat raisins, graham crackers, or candy. You could also drink skim milk, regular (not diet) soda, or fruit juice. You may also take glucose tablets.

It’s a good idea to find out about health problems or situations that can lead to low blood sugar. It’s also important to pay attention to your health and lifestyle. For example, talk to your doctor to see if you can change your diet, change the medicines you take, or change the way you exercise. In some cases, treating the health problem that is causing low blood sugar can prevent future problems.

What should you do in an emergency?

If mild or moderate hypoglycemia isn't treated right away, it can turn into severe hypoglycemia. People with severe hypoglycemia usually pass out. If you pass out, someone should call 911 right away. It’s a good idea to teach your family, friends, and co-workers ahead of time about the symptoms of low blood sugar so they'll know what to do.

Frequently Asked Questions

Learning about hypoglycemia:

Being diagnosed:

Getting treatment:


The symptoms of hypoglycemia may vary from episode to episode because low blood sugar can be mild, moderate, or severe. Increasingly severe symptoms appear as the blood sugar level falls.

In healthy people, fasting blood sugar levels are usually between 4.0 and 6.0 millimoles per litre (mmol/L).

Mild hypoglycemia

Symptoms of mild low blood sugar usually occur when blood sugar falls below 3.0 to 4.0 mmol/L and may include:

  • Nausea.
  • Extreme hunger.
  • Feeling nervous or jittery.
  • Cold, clammy, wet skin and/or excessive sweating not caused by exercise.
  • A rapid heartbeat (tachycardia).
  • Numbness or tingling of the fingertips or lips.
  • Trembling.

Moderate hypoglycemia

If blood sugar continues to fall, the nervous system will be affected. Symptoms usually occur when the blood sugar falls below 3.0 mmol/L and may include:

  • Mood changes, such as irritability, anxiety, restlessness, or anger.
  • Confusion, difficulty in thinking, or inability to concentrate.
  • Blurred vision, dizziness, or headache.
  • Weakness, lack of energy.
  • Poor coordination.
  • Trouble walking or talking, such as staggering or slurred speech.
  • Fatigue, lethargy, or drowsiness.

Severe hypoglycemia

The symptoms of severe low blood sugar develop when blood sugar falls below 2.0 mmol/L and may include:

  • Seizures or convulsions.
  • Loss of consciousness, coma.
  • Low body temperature (hypothermia).

Prolonged severe hypoglycemia can cause irreversible brain damage and heart problems, especially in people who already have coronary artery disease. If emergency medical treatment is not provided, severe hypoglycemia can be fatal.

Some medicines may mask symptoms of low blood sugar, including beta-blockers, which are often used to treat heart conditions and high blood pressure.

What to think about

Different people may have symptoms of mild, moderate, or severe hypoglycemia at varying blood sugar levels. Although the blood sugar levels listed above are typical, they may not apply to everyone. If your blood sugar drops suddenly, you may have symptoms even if your level is in the normal range.

A number of medical conditions can cause symptoms similar to those of hypoglycemia. Your doctor will use blood tests and other measures to make sure another condition isn't causing your symptoms.

If you have diabetes, it is very important to check your blood sugar levels, because many diabetes treatments can cause low sugar levels.

Examinations and Tests

Doctors diagnose hypoglycemia when a person has these three things:

  • Symptoms of low blood sugar.
  • A blood glucose laboratory test with low results. This is different from a test done with a glucose meter.
  • Relief of symptoms when the blood sugar is raised.

Medical history

Your doctor will ask questions about:

  • What symptoms you typically have—how long they last, when they occur, how often they occur, and what happens to your symptoms when you eat something.
  • Past medical treatments, current medical conditions, and whether you are taking medicines (bring all medicines, both prescription and non-prescription, to your appointment for review) or receiving other treatment.
  • Diet and nutrition, such as what and when you eat, and whether you have had recent changes in your eating or bowel habits.
  • Whether you have gained or lost weight recently.

Because an episode of hypoglycemia can impair mental functioning, your doctor may also want to talk to friends or relatives who have seen your symptoms.

Your doctor will assess your medical history to see if any of the following could be causing your hypoglycemia:

  • Illnesses and other health conditions. Hypoglycemia may occur when other diseases and disorders affect the body's sugar metabolism. These can include disorders of the pancreas and endocrine system; diseases of the liver, adrenal glands (such as Addison's disease), or kidneys; heart failure, which can impair liver function; and sepsis. In very rare cases, non-pancreatic tumours cause hypoglycemia.
  • Medicines. Some medicines used to treat conditions other than diabetes can cause hypoglycemia or hide its symptoms.
  • Too much insulin. Tumours in the pancreas (insulinomas), certain disorders of the pancreas, or some autoimmune diseases can cause too much insulin to be produced. These conditions are rare.
  • Alcohol. In some people, drinking alcohol can cause a drop in blood sugar levels. Hypoglycemia has been linked to chronic alcoholism and binge drinking. Hypoglycemia linked to binge drinking can be particularly severe if a person has not eaten within about 6 hours, because fasting can impair the liver's ability to make new glucose. The person may fall into a coma, which can be fatal.
  • Alimentary hypoglycemia. Hypoglycemia within 1 to 2 hours after a meal sometimes occurs when stomach contents empty into the intestines too rapidly. This causes the rapid absorption of glucose into the blood and an overproduction of insulin (hyperinsulinism) in response. This problem may occur after surgery for peptic ulcers, obesity, or other stomach problems.
  • Other causes. Hypoglycemia also may occur, though rarely, under certain conditions in early pregnancy or with prolonged fasting or missed meals, severe malnutrition, significant weight loss, or prolonged strenuous exercise, such as running a marathon. It may occur in premature or full-term newborns with a low birth weight and in newborns whose mothers have been treated for type 1 diabetes or gestational diabetes.
  • Inborn metabolic problems. In rare cases, hypoglycemia may be caused by inherited enzyme or hormone deficiencies, especially those that affect the metabolism of sugars and other carbohydrates. These conditions are often discovered in infancy or childhood.
  • Factitious hypoglycemia. Hypoglycemia can be caused intentionally by the inappropriate use of insulin and sulfonylurea medicines. This is most often seen in health professionals and people who have diabetes or their relatives. The reasons for self-induced hypoglycemia vary and may be associated with psychiatric problems or a need for attention, similar to Munchausen syndrome.

Physical examination

Your doctor also will look for conditions that may cause hypoglycemia, including signs of:

  • Liver disease, such as an enlarged liver.
  • Kidney disease, such as swelling (edema), and too much urea in the blood.
  • Malnutrition, such as extreme weight loss.
  • Adrenal gland disease, such as too much pigment (colour) in the skin and/or low blood pressure.

Primary laboratory tests

Often hypoglycemia is a complication of diabetes treatment. If you are not being treated for diabetes or another obvious cause of low blood sugar, you will have tests to confirm hypoglycemia. Ideally, your doctor will want to do these tests when you are experiencing symptoms. But because this is usually not possible, you probably will have tests that try to reproduce symptoms. These tests are usually done in a clinic or a hospital.

In some cases, home glucose monitors, which are often used by people who have diabetes, may be used to evaluate possible hypoglycemia. But a low blood sugar reading needs to be confirmed by these formal laboratory tests:

  • Overnight fast. You will be asked not to eat overnight. And you will have your blood sugar and insulin levels checked the following morning. In many cases, this test will tell your doctor if you have fasting hypoglycemia.
  • Prolonged supervised fast. The primary test for hypoglycemia is a prolonged (48- to 72-hour) supervised fast. You will be asked to fast until the symptoms of moderate low blood sugar develop or until laboratory blood glucose levels drop below 2.5 mmol/L. This test also can help your doctor find out why confirmed hypoglycemia is occurring. During the prolonged supervised fast test, your blood is drawn at regular intervals to monitor how well your body controls blood sugar levels. Laboratory tests measure substances in the blood, such as glucose, insulin, and C-peptide.
  • Mixed meal test. If you have symptoms of hypoglycemia after you eat (post-prandial), you will be asked to eat a meal with foods you think cause your symptoms. Sometimes a nutritional supplement is used instead of a meal. You will be watched for symptoms of low blood sugar. And your blood will be drawn and sent to a lab to test substances in your blood such as glucose, insulin, and C-peptide. This test can last up to 5 hours.

Other tests

A urine or blood test may be done to look for substances called ketones that the body produces when it breaks down fat for energy. Insulin prevents the production of ketones. If you have low blood sugar from too much insulin, your body will not produce ketones. In people who have normal insulin release, prolonged fasting causes a drop in insulin and an increase in ketone production.

Tests also may be done to look for a tumour of the pancreas or an endocrine disorder.

If the suspected cause is rapid emptying of the stomach after a meal (reactive or alimentary hypoglycemia) or a tumour in the pancreas or other part of the body, you may have imaging tests, such as ultrasound, CT scan, or MRI, to examine your stomach, pancreas, or other internal organs. In some cases, pancreatic tumours are quite small, so an imaging test in which a dye is injected into the blood vessels (angiography) may be used to find the tumour. Other imaging tests use radioactive proteins that bind to tumours. This helps the doctor locate a tumour. Imaging tests may be needed regularly for several years, because such tumours can be hard to find.

Treatment Overview

You can treat a sudden (acute) episode of hypoglycemia by eating or drinking some form of sugar to return your blood sugar to a normal range. This treatment is usually all that is needed for an isolated episode of hypoglycemia, such as from prolonged fasting or strenuous exercise without adequate food.

Hypoglycemia caused by a long-term (chronic) health condition requires treatment of the long-term health condition.

Treatment of acute hypoglycemia

  • If you are conscious and able to respond when symptoms start, eat or drink some form of sugar. Drink fruit juice or sugared (non-diet) soda pop, or eat sugar in the form of candy, cubes, or tablets, or eat some quick-sugar food.
  • Make sure your family members, co-workers, and others close to you are aware that you may have episodes of hypoglycemia, so they can help you. Wear medical information on a badge or bracelet if you are at risk for moderate or severe hypoglycemia, in case an episode occurs when you are away from family, friends, or caregivers. Emergency treatment for low blood sugar usually does not require glucagon, but it may be needed in rare cases.
  • Tell the people close to you that they should call 911 or other emergency services if you become sleepy or unconscious. They also should seek emergency help if you are not unconscious but they do not know how to give you an injection of glucagon. Always have a medical alert bracelet or tag with you. Medical alert jewellery can be bought in pharmacies or on the Internet.
  • Severe cases of hypoglycemia may require a hospital stay. You may be given additional glucose in a vein (intravenously) until your blood sugar level is stable in the normal range. This could take several days, depending on the cause.
  • Future episodes of low blood sugar may be avoided if you change the behaviour or situation that led to the hypoglycemia. If medicine causes hypoglycemia, you may be able to stop using it or change how it is used. Talk to your doctor about how to prevent future episodes of low blood sugar.
  • Remember that low blood sugar may be only temporarily corrected with acute treatment, and you may need additional treatment. If you have a glucose meter, you should recheck your blood sugar level in 10 to 15 minutes. If you do not have a blood glucose meter, you should be alert for the return of low blood sugar symptoms and be prepared to seek emergency care.

Treatment of hypoglycemia caused by another condition

If you have low blood sugar caused by a chronic health condition, your symptoms will be treated the same as those of acute hypoglycemia. After you have recovered from the immediate symptoms, you will need treatment for the condition that is causing hypoglycemia. In many situations, after the cause is identified, new episodes of hypoglycemia can be prevented.

Low blood sugar may have a long-term cause that can be cured, such as some endocrine disorders or diseases of the liver, adrenal glands, or pancreas. Effective long-term treatment of an insulin-producing tumour in the pancreas (insulinoma) usually requires surgery.

Even if the condition that is causing your hypoglycemia is not curable, treatment often can prevent episodes of low blood sugar. Talk to your doctor about whether you can modify your diet (what, when, or how much you eat), change the dosage or types of medicines you take, or modify your physical activity (such as when and how hard you exercise).

This type of management is most common for people who have diabetes, other chronic health conditions that may require long-term treatment (liver disease, kidney failure, or endocrine disorders), and inherited enzyme or hormone deficiencies. It may also be useful for people who have alcohol-related illnesses.

Home Treatment

If you are at risk for hypoglycemia, you need to know about health conditions or situations that may lead to low blood sugar and how to deal with them. Proper attention to your health and lifestyle can help you prevent hypoglycemia.

Learn the early symptoms of hypoglycemia and take steps to deal with low blood sugar immediately.

When your blood sugar drops too low, drink fruit juice or sugared (non-diet) soda pop. Or eat sugar in the form of candy, cubes, or tablets. Or eat quick-sugar foods.

Members of your household, close friends, and co-workers also should know the symptoms of low blood sugar and learn about emergency care. Wear medical information on a badge or bracelet if you are at risk for moderate or severe hypoglycemia, in case an episode occurs when you are away from family, friends, or caregivers.

Emergency care

Emergency care for low blood sugar for people who are not taking insulin includes consuming some kind of quick-sugar food, such as fruit juice or glucose tablets as long as you are able to swallow. (Use this information if you do not know whether a person with hypoglycemia takes insulin.)

Health and lifestyle management to prevent hypoglycemia

When hypoglycemia occurs because of an isolated, short-term cause such as prolonged fasting or strenuous exercise, further medical treatment is usually not needed. You may simply need to talk with your doctor about how to avoid such behaviours or situations.

When hypoglycemia has a chronic cause that is not curable, treatment of the condition often can prevent episodes of low blood sugar. Talk with your doctor about:

  • Modifying your diet with a long-term meal plan (what, when, and how much you eat).
  • Changing the dosage or types of medicines you take.
  • Adjusting the timing and level of your physical activity (such as when and how hard you exercise).
  • Keeping a diary of low blood sugar symptoms (when they occur and what and when you last ate).

Managing your diet to prevent hypoglycemia is especially important if you have diabetes, inherited enzyme or hormone deficiencies, or non-fasting (post-prandial) hypoglycemia.

Your doctor will want to see you for a physical examination every year (annual) or more often if your symptoms become frequent. You and your doctor will discuss your home blood-sugar monitoring records and your diary of your symptoms.

Other Places To Get Help


Canadian Diabetes Association
National Life Building
1400-522 University Avenue
Toronto, ON  M5G 2R5
Phone: (416) 363-0177
1-800-BANTING (1-800-226-8464)
Fax: (416) 408-7117
Email: info@diabetes.ca
Web Address: http://www.diabetes.ca

The Canadian Diabetes Association (CDA) is devoted to meeting the needs of people with diabetes in Canada. This organization provides general information about diabetes and its care. It organizes summer camps for young people with diabetes and conducts educational seminars to help people manage their diabetes. The CDA also sells a range of products, including cookbooks, in its stores.

Dietitians of Canada
480 University Avenue
Suite 604
Toronto, ON  M5G 1V2
Phone: (416) 596-0857
Fax: (416) 596-0603
Email: centralinfo@dietitians.ca
Web Address: www.dietitians.ca

The Dietitians of Canada website provides a wide range of food and nutrition information, including fact sheets on frequently asked food and diet questions, quizzes and other tools to assess your diet habits, and meal planning guides.

Health Canada Food and Nutrition
Health Canada
Web Address: www.hc-sc.gc.ca/fn-an/index_e.html

The mission of the Food and Nutrition program is to protect and improve the health of the people of Canada through science-based policies and programs related to safe and nutritious food.


Other Works Consulted

  • Amiel SA (2005). Iatrogenic hypoglycemia. In CR Kahn et al., eds., Joslin's Diabetes Mellitus, 14th ed., pp. 671–686. Philadelphia: Lippincott Williams and Wilkins.
  • Cryer PE (2008). Glucose homeostasis and hypoglycemia. In HM Kronenberg et al., eds., Williams Textbook of Endocrinology, 11th ed., pp. 1503–1533. Philadelphia: Saunders Elsevier.
  • Cryer PE (2008). Hypoglycemia. In AS Fauci et al., eds., Harrison's Principles of Internal Medicine, 17th ed., vol. 2, pp. 2305–2310. New York: McGraw-Hill.
  • Endocrine Society (2009). Evaluation and management of adult hypoglycemic disorders: An endocrine society clinical practice guideline. Journal of Clinical Endocrinology and Metabolism, 94(3): 709–728. Available online: http://www.endo-society.org/guidelines/final/upload/FINAL-Standalone-Hypo-Guideline.pdf.
  • Glaser B, Leibowitz G (2005). Hypoglycemia. In CR Kahn et al., eds., Joslin's Diabetes Mellitus, 14th ed., pp. 1147–1175. Philadelphia: Lippincott Williams and Wilkins.
  • Masharani U, Gitelman SE (2007). Hypoglycemic disorders. In DG Gardner, D Shoback, eds., Greenspan’s Basic and Clinical Endocrinology, 8th ed., pp. 748–769. New York: McGraw-Hill.
  • Service FJ (2007). Hypoglycemia. In DC Dale, DD Federman, eds., ACP Medicine, section 3, chap. 9. New York: WebMD.


By Healthwise Staff
Primary Medical Reviewer E. Gregory Thompson, MD - Internal Medicine
Primary Medical Reviewer Donald Sproule, MD, CM, CCFP, FCFP - Family Medicine
Specialist Medical Reviewer Alan C. Dalkin, MD - Endocrinology
Last Revised May 11, 2011

This information does not replace the advice of a doctor. Healthwise, Incorporated disclaims any warranty or liability for your use of this information.