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Healtheuniversity > English > Diabetes College > Treat Diabetes > Manage Your Blood Sugar > What is Low Blood Sugar (Hypoglycemia)?

What is Low Blood Sugar (Hypoglycemia)?

Low blood sugar means there is not enough sugar in your blood. Low blood sugar can be very dangerous because your body needs sugar to function.

Low blood sugar happens when your blood sugar drops below 4 mmol/L, but you may have signs of low blood sugar at different levels.

  • Check your blood sugar often. You may not have any signs of low blood sugar.
  • Teach your family members and friends how to help you when you can no longer treat your blood sugar by yourself.
  • Know the signs of low blood sugar.

Low blood sugar can be very dangerous. It means there is not enough sugar in your blood. Your body needs sugar to function. Low blood sugar is also known as hypoglycemia.

Low blood sugar happens when your blood sugar drops below 4 mmol/L. You may have signs of low blood sugar at different levels. For example, you may have signs of low blood sugar at 6 mmol/L.

If your blood sugar gets too low you can become disoriented, confused, you may even lose consciousness (go into a coma). This is called severe hypoglycemia.

Severe hypoglycemia happens when your blood sugar is so low you cannot treat it yourself with fast acting carbohydrates or glucagon (a medicine sometimes prescribed by doctors for people who are prone to very low blood sugar).

Teach your family members and friends how to help you when you can no longer treat your low blood sugar by yourself. They need to know this is a medical emergency and you need help right away.

What Are The Signs Of Low Blood Sugar?

People have different signs of low blood sugar. You may have any number of the signs below.

Common signs are:

  • trembling or shaking
  • hard time thinking
  • headache
  • dizzy
  • feeling tired (drowsy)
  • changes to your vision 
  • anxiety (nervous and fearful)
  • tingling in your face or hands
  • nausea 
  • sweating
  • hunger
  • faster heart beat than usual (palpitations)
  • difficulty speaking
  • disoriented (confused)
  • seizures or loss of consciousness (with severe hypoglycemia)

Some people have low blood sugar levels and do not have any of the signs listed. In this case, it is crucial that you check your blood sugar often to see if your blood sugar is low (especially before driving a car, motorcycle or boat). Check your blood sugar often to be sure. This will help you know when your blood sugar is low.

What Is The Impact Of Low Blood Sugar?

Having low blood sugar is a risk to your safety and health.

  • Do not use machinery or drive a vehicle if your blood sugar is low. You are at a greater risk of an accident if your blood sugar is low.
  • If you have an episode of low blood sugar this puts you at risk of not being able to notice the next time your blood sugar goes low.
  • You may have a higher risk of dementia (loss of memory or thinking skills) if you have Type 2 diabetes and have many severe episodes of low blood sugar.
Last Reviewed: 10/16/2016