Hypoglycemia is a condition that occurs when your blood sugar (glucose) is too low.

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


Hypoglycemia occurs when:

  • 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

Insulin is a hormone that reduces blood sugar. It is produced by the pancreas in response to increased glucose levels in the blood.

The most common causes of low blood sugar in people with diabetes are:

  • Taking your insulin or diabetes medicine at the wrong time
  • Taking too much insulin or diabetes medicine by mistake
  • Not eating enough during meals or snacks after you have taken insulin or diabetes medicine
  • Skipping meals
  • Waiting to eat your meals
  • Exercising more or at a different time than usual
  • Drinking alcohol

If you have diabetes and are taking any of the following diabetes medications, you have a risk for low blood sugar:

  • Chlorpropamide (Diabinese), tolazamide (Tolinase), acetohexamide (Dymelor), glipizide (Glucotrol), or tolbutamide (Orinase)
  • Glyburide (Micronase), glimepiride (Amaryl), repaglinide (Prandin), nateglinide (Starlix), and mitiglinide) -- the risk with these drugs is lower, but still possible
  • Insulin

A newborn's blood sugar can become low. Babies who are born to mothers with diabetes may have severe drops in blood sugar.

Hypoglycemia in people who do not have diabetes may be caused by:


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
  • Hunger
  • Shaking or trembling
  • Sleeping trouble
  • Sweating
  • Tingling or numbness of the skin
  • Tiredness or weakness
  • Unclear thinking

Sometimes your blood sugar may be too low, even if you do not have symptoms. If your blood sugar gets too low, you may:

Exams and Tests

Home monitoring of blood sugar will show readings lower than 70 mg/dL.

Serum glucose test will be low.


Treatment depends on the cause.

If you have diabetes, check your blood sugar level whenever you have symptoms of low blood sugar. If your blood sugar is low (70 mg/dL), you need to treat yourself right away.

Eat something that has about 15 grams of carbohydrates. Examples are:

  • 3 glucose tablets
  • A 1/2 cup (4 ounces) of fruit juice or regular, non-diet soda
  • 5 or 6 hard candies
  • 1 tablespoon sugar, plain or dissolved in water
  • 1 tablespoon honey or syrup

Wait about 15 minutes before eating anything else. Be careful not to over-treat by eating too much. This can cause high blood sugar and weight gain.

Check your blood sugar again.

  • If you don't feel better in 15 minutes and your blood sugar is still low (less than 70 mg/dL), eat something that has 15 grams of carbohydrates again.
  • You may need to eat a snack that has carbohydrates and protein if your blood sugar is in a safer range (over 70 mg/dL) and your next meal is more than an hour away.

If these steps for raising your blood sugar do not work, call your doctor right away.

Persons with severe hypoglycemia are treated with glucose injections or the hormone glucagon. Immediate treatment is needed to prevent serious complications or death.

If hypoglycemia is caused by an insulinoma (insulin-releasing tumor), surgery to remove the tumor is the best treatment.

Possible Complications

Untreated, hypoglycemia from too much insulin can lead to loss of consciousness and coma.

Severe hypoglycemia is a medical emergency that may cause seizures and permanent damage to the nervous system if not treated. Severe hypoglycemia in which you become unconscious is also called insulin shock.

Learn to recognize the early warning signs of hypoglycemia and treat yourself quickly.

When to Contact a Medical Professional

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

  • GET A RIDE to the emergency room, or
  • Call a local emergency number (such as 911)

DO NOT drive when your blood sugar is low.

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

  • Becomes less alert
  • Cannot be woken up


If you have diabetes, follow your doctor's advice about diet, medicine, and exercise.

Preventing low blood sugar is better than having to treat it. When you exercise, check your blood sugar levels. Make sure you have snacks with you if you take insulin or other medicines that lower your blood sugar.

Ask your doctor or nurse if you need to eat a bedtime snack to prevent low blood sugar overnight. Protein snacks may be best.

Do not drink alcohol without eating food. If you do drink, have only one or two drinks at the most.

Your doctor may tell you to change your diet so that you get even amounts of sugar into your body throughout the day. You may be told to eat small, frequent meals that contain complex carbohydrates, fiber, and fat, and to avoid simple sugars, alcohol, and fruit juice.

Eat meals at regular times. Eat extra food when you exercise more.

If you have a history of hypoglycemia, keep a snack or drink containing sugar with you at all times. Eat the snack as soon as symptoms appear.

Alternative Names

Insulin shock; Low blood sugar


American Diabetes Association. Standards of medical care in diabetes--2011. Diabetes Care. 2011;34 Supl 1:S11-S61.

Cryer PE. Glucose homeostasis and hypoglycemia. In: Kronenberg HM, Melmed S, Polonsky KS, Larsen PR. Kronenberg: Williams Textbook of Endocrinology. 11th ed. Philadelphia, Pa: Saunders Elsevier; 2008:chap 33.

Update Date: 4/28/2012

Reviewed by: Ari S. Eckman, MD, Division of Endocrinology, Diabetes and Metabolism, Trinitas Regional Medical Center, Elizabeth, NJ. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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