Blood Glucose Testing

Glucose is a type of sugar that is found in your blood. Blood glucose testing is a big part of caring for your diabetes. A blood glucose test tells you how much sugar is in your blood at any point in time. Many things affect your blood glucose levels each day. Testing will let you know if your meal plan, medication and exercise are working to carefully manage your blood glucose.

Who Should Test Their Own Blood Glucose?

CDA recommends:

  • People with type 1 test at least three times a day.
  • People with type 2 on oral medication or insulin test at least one time a day.

Testing frequency should be individualized depending on gylcemic control and type of therapy. More frequent testing may be required to make behavioural or treatment adjustments.

Diabetes changes the way your body controls blood glucose levels. Self-testing helps you keep your blood glucose levels as close to normal as you can.

How Can Blood Glucose Self-Testing Help Me?

You and your health care team have set up a plan to help you manage your blood glucose. One of the best ways to be sure your plan is working is to test your blood glucose yourself. Research shows that proper management of blood glucose can lower your risk of eye disease, kidney disease and nerve damage that can develop due to diabetes. Self-testing shows you how your body reacts to daily events. You can answer questions like, "What happens to my blood glucose during times of stress or when I am sick?" or "What happens to my blood glucose when I exercise?" Self-testing can help you decide how to take better care of yourself.

How Often Should I Test My Blood Glucose?

The more you test, the more you will know about your blood glucose management. Many things affect your blood glucose each day, like eating, exercise, medication, illness and stress. So, it is important to test your blood glucose at different times of the day. Research studies show that testing your blood glucose daily, up to four times or more, is a good way to learn how to better manage your blood glucose. Good management of blood glucose will help you lower your risk of future problems with diabetes. Self-testing gives you the information you need to avoid too many high or low blood glucose levels day-to-day. Your health care team will help you decide how often to test.

CDA recommends:

  • People with type 1 test at least three times a day.
  • People with type 2 on oral medication or insulin test at least one time a day.

Testing frequency should be individualized depending on glycemic control and type of therapy. More frequent testing may be required to make behavioural or treatment adjustments.

Diabetes changes the way your body controls blood glucose levels. Self-testing helps you keep your blood glucose levels as close to normal as you can.

When Should I Test My Blood Glucose?

Your health care team will also help you decide when to test. Testing at different times is a good idea. Here are some useful times to choose from:

  • Before breakfast. This is called the fasting blood glucose. Fasting means you have not had any food in eight hours or more.
  • One to two hours after breakfast. This is called the postprandial blood glucose.
  • Before lunch.
  • One to two hours after lunch.
  • Before supper.
  • One to two hours after supper.
  • Before bedtime.
  • At 2:00 or 3:00 a.m., if you take insulin.

It is a good idea to do extra tests when:

  • There are changes in your treatment plan.
  • You start any new medication.
  • You think your blood glucose might be too low or high.
  • You are sick.

How Do I Make Sense of Different Blood Glucose Levels at Different Times?

Blood tests at different times will indicate how well your medication is working. For instance, research shows that blood glucose levels in people with diabetes can more than double after eating (postprandial), even when their blood glucose before eating is normal. It is helpful to talk about your fasting and postprandial glucose goals with your health care team.

Do I Really Need to Keep Records?

Yes, keep a written record (logbook) of your blood glucose readings like the Clinilog found in the box of your Bayer Diabetes Care System. Also, write down the date, time and whether the self-test was done before or after eating. Some meters like Bayer's CONTOUR®, CONTOUR® LINK and BREEZE®2 store this information for you. You can note information about diet, exercise, medication or how you are feeling. Always bring your record book when you visit your health care team. Together, you can look for patterns in your blood glucose readings. The patterns help you decide whether you need to adjust your plan. A time-saving way to look for patterns is by using WinGlucofacts™ Diabetes Management Software if you have a computer. You also can try using the Online Blood Glucose Log found on this site.

What Can I Do to Improve My Self-Testing?

Follow the directions that come with the meter you are using. Talk to your health care team about your meter and the best way to self-test. These tips will help you get the most correct results.

  • Keep your meter clean.
  • Keep your testing supplies at room temperature.
  • Check the expiration date of your testing supplies.
  • Wash your hands in warm, soapy water.
  • Dry them well.
  • Put your hand down to let gravity help the blood flow to your fingertips.
  • Prick the side of your finger with a fresh lancet in a lancing device.
  • Get a big enough drop of blood to fill the test strip.
  • Record your results.

What Do I Do if My Blood Glucose Levels are High?

  • Think about why your high blood glucose level might be high and make a note of it.
  • Drink more water and sugar-free fluids (limit fluids with sugar, including fruit juices).
  • Follow your recommended meal plan (if you do not have a plan, meet with your dietitian).
  • Take your medication as prescribed by your doctor. If your blood glucose remains high, see your doctor or diabetes educator.
  • Test your blood glucose more often (every three to four hours).
  • If your blood glucose level is below 14 mmol/L and you feel well, increase your physical activity (for example, go for a walk). Always ask your doctor before starting a new exercise routine.

What Do I Do if My Blood Glucose Levels are Low?

  • Eat or drink fast-acting sugar such as:
    • 15 mL (three teaspoons) of sugar disolved in water
    • 15 mL of honey
    • 15 g of glucose in the form of glucose tablets
    • 6 Life Savers®
    • 175 mL (3/4 cup) of regular soft drink or juice
  • Wait 15 minutes, then check your blood glucose again. If your blood glucose is still below 4 mmol/L, repeat treatment and blood glucose test again.
  • Follow with one portion of starch and one portion of protein if your next meal is more than one hour away.

The more you test, the more you will know about your blood glucose management. Ask your doctor or diabetes educator what your levels should be.