Warning Signs for Low or High Blood Glucose


Hypoglycemia occurs when your blood glucose drops too low—usually less than 4 mmol/L.
This is caused by:

  • Not eating enough food
  • Missing or delaying a meal
  • Exercising without taking the necessary precautions
  • Taking too much insulin
  • Drinking alcohol

Low blood glucose can happen quickly, so it is important to take care of it right away.

The warning signs of low blood glucose

You may feel:

  • Hungry
  • Shaky or light-headed
  • Nervous or irritable
  • Sweaty
  • Weak
  • Nauseous
  • Your heart beats at a faster rate
  • Confused
  • A numbness or tingling in your tongue or lips

You may also:

  • Have difficulty concentrating, seeing or speaking
  • Feel confused, weak, or unusually sleepy
  • Have a headache
  • Feel dizzy
  • Experience mood changes
  • Make note of your symptoms to help you to identify low blood glucose in the future.

How to treat low blood glucose

  • Check your blood glucose. If you do not have your meter with you, treat the symptoms anyway. It is better to be safe.
  • Eat or drink 15 grams of carbohydrate such as:
       - 15 grams of glucose, in the form of glucose tablets
       - 15 mL (3 teaspoons) or 3 packets of table sugar dissolved in water
       - 175mL (3/4 cup) of juice or regular pop
       - 6 Life Savers™ (1 = 2.5 gram of carbohydrate)
       - 15mL (1 tablespoon) of honey
  • Wait 10 to 15 minutes, then test your blood glucose again.

If your blood glucose is still below 4.0 mmol/L:

  • Treat again

If your next meal is more than one hour away, or if you are going to be active, eat a snack, such as half a sandwich or cheese and crackers (something with carbohydrate and protein).

Remember: Some people do not have early warning signs of low blood glucose. These individuals must check their blood glucose levels more often to avoid this condition. It is especially important for all people with diabetes to check their glucose level before driving a car.

Severe low blood glucose:

If your blood glucose drops very low you may:

  • Become confused and disoriented
  • Lose consciousness

You will need assistance from another person to treat severely low blood glucose. Make sure you always wear MedicAlert® identification and tell people in your daily life that you have diabetes, so they can recognize the symptoms and get help for you. Talk to your doctor or diabetes educator about prevention and emergency treatment for severe low blood glucose.


High blood glucose (hyperglycemia) can result when food, activity and insulin are not balanced. High blood glucose may happen when you are sick or under stress.

The signs of high blood glucose

You may be:

  • Thirsty
  • Urinating more often
  • Tired

If you think your blood glucose is high, check your blood glucose level
Your doctor or diabetes educator will teach you how to adjust your food and medication if your blood glucose levels are high.

If your blood glucose level is very high (greater than 14.0 mmol/L) and you have symptoms such as nausea, vomiting or abdominal pain, you should check your urine for ketones (your doctor or diabetes educator will teach you how to do this).

Ketones are acids that build up in the blood. They appear in the urine when your body doesn't have enough insulin. Seek medical assistance immediately if ketones are present.

Last updated: Tue, 2012-11-06 16:16