Lahey Health is now part of Beth Israel Lahey Health

by Alan R
(Low Blood Glucose; Low Blood Sugar)


Hypoglycemia is a low level of glucose in the blood. Glucose is your body's main source of energy. Low levels make it hard for your body to work as it should. This will cause a wide range of problems.


Certain health problems may make it hard for your body to balance glucose.

Some diabetes meds can lower glucose. It is a common cause of hypoglycemia. The meds alone can lower blood glucose levels. However, other things can play a role such as:

  • Taking too much blood sugar-lowering medication
  • Delaying or missing meals, or eating too little at meals
  • Unplanned intense exercise
  • Sickness like cold or flu

Hypoglycemia can also happen in people without diabetes. It is less common. This type may be caused by:

  • Alcohol use disorder , binging while with not eating is the worst case
  • Starvation
  • Early pregnancy
  • Hormone imbalances from some pituitary or adrenal gland problems
  • Certain liver problems
  • Kidney disease
  • Certain types of stomach surgery
  • Tumor that makes insulin
  • Severe illness or infection

Risk Factors

Factors that may increase your chances of hypoglycemia:

  • Taking medicines that lower blood sugar levels
  • Drinking too much alcohol
  • Fasting (worse when it happens with intense exercise)


Symptoms may come on slowly or quickly. Hypoglycemia may cause:

  • Sweating
  • Nervousness
  • Lightheadedness
  • Rapid heartbeat
  • Hunger
  • Headache
  • Tingling feeling around the mouth

As hypoglycemia worsens, it may cause:

  • Fatigue
  • Weakness
  • A change in behavior or confusion
  • Poor control of movements
  • Seizure
  • Loss of consciousness

Early symptoms may start to fade if you have a lot of events. The symptoms may stop all together. This means you will not have early warning. It will increase the chance of a having a severe drop in glucose. Get to know your early signs. Quick care can stop future problems.


You will be asked about your symptoms and health past. An exam will be done.

Your doctor will try to track your low blood glucose. Your blood glucose levels will need to be measured while you are having symptoms. This is a common step with diabetes care.

If you do not have diabetes, other tests may need to be done. This may include checking your blood levels after fasting.


Treatment will bring blood glucose levels back to normal. This will make a quick fix. Other steps may be needed to keep it from occurring again.

Mild Hypoglycemia

In people who can eat or drink, symptoms of low blood sugar can be relieved quickly by:

  • Eating sugar that is easily passed into blood, such as:
    • Fruit juice
    • Sugared soft drink
    • Table sugar in water
    • Honey or corn syrup
  • Taking glucose tablets

Once blood glucose has risen to normal levels, a snack or meal can help to keep levels stable.

Severe Hypoglycemia

If someone is not conscious, care may need to be delivered such as:

  • Glucagon—a hormone that raises blood sugar levels
  • IV glucose


To help reduce your chance of hypoglycemia:

  • For people with diabetes:
    • Check your medicine. Take it as prescribed.
    • Follow the food and exercise plans given by your doctor.
    • Check your blood glucose often.
    • Avoid drinking too much alcohol.
  • For people without diabetes:
    • Avoid drinking too much alcohol.
    • Eat frequent, small meals.
    • Eat enough food before exercising.

If you have frequent bouts of severe hypoglycemia:

  • Wear a medical alert bracelet or ID.
  • Note your early symptoms. Take quick steps to fix low blood glucose.


American Diabetes Association 

Hypoglycemia Support Foundation 


Canadian Diabetes Association 

Health Canada  https://www. 


Hypoglycemia (low blood glucose). American Diabetes Association website. Available at: Updated July 1, 2015. Accessed October 2, 2017.

Hypoglycemia in diabetes. EBSCO DynaMed Plus website. Available at:  . Updated February 7, 2017. Accessed October 2, 2017.

Hypoglycemia in persons without diabetes. EBSCO DynaMed Plus website. Available at:  . Updated February 23, 2015. Accessed September 28, 2016.

Low blood glucose (hypoglycemia). National Institute of Diabetes and Digestive and Kidney Diseases website. Available at: Updated August 2016. Accessed October 2, 2017.

Revision Information

  • Reviewer: EBSCO Medical Review Board Marcin Chwistek, MD
  • Review Date: 09/2018
  • Update Date: 08/30/2018