Blood Glucose Monitoring

by diabetes care guide

What do blood glucose meters do?

Like a speedometer on your car helps you control your speed, blood glucose meters help you control your blood glucose. Blood glucose readings let you know what your blood glucose level is at the moment you take it. They help you understand how the food you eat, the activities you do and the medications you take affect your glucose level.

A glucose meter is a small, portable machine that comes with a lancing device specially designed to draw a small sample of blood from your fingertip as painlessly as possible. Once you have a small drop of blood on your fingertip, you place it on a test strip, which is then inserted into and read by the meter.

There are many models of blood glucose meters available in Canada. Each model offers its own combination of features. It is helpful to discuss which meter is best for you with your diabetes educator or pharmacist.

Meters are usually obtained at retail pharmacies or diabetes education centres. If you are going to purchase a meter for the first time, ask for training from the pharmacist or diabetes educator. Call ahead and schedule an appointment to learn the best technique for accurate results.


  • Before testing wash your hands with warm water and soap, and dry them well. Avoid alcohol, as it can dry your skin.
  • Set your lancing device at a comfortable depth. Try a different lancing device if the one you are using is not comfortable.
  • Look for lancets that are thinner and shorter, and ensure they will fit in your lancing device.
  • Replace the lancet each time you use it.
  • When testing, use the sides of your fingertips and rotate amongst your fingers.
  • Discard your lancet and strips in a sharps-rated container. Check with your pharmacy for options available in your community.
  • Store your strips in the appropriate container or packaging away from sunlight and moisture.


What affects blood glucose levels?

A drop in blood glucose levels can be caused by:

Type and amount of food
Delaying or skipping a meal, or having a meal with less carbohydrate than you normally eat.

More activity than usual
If you increase your level of activity, your blood glucose levels can drop. Whenever you start a new activity, monitor more frequently to watch for glucose changes.

More medication than usual
When you have more diabetes medication than normal (an extra dose for example) blood glucose levels can drop. The signs of low blood glucose (hypoglycemia) include shaking, confusion, extreme hunger, sweating, fatigue, moods swings, a rapid heart beat or even passing out.

If you feel signs that your blood glucose is low, check it. (Low is defined as less than 4mmol/L)
Low blood glucose can happen quickly, so it’s important to treat it right away. If your blood glucose drops very low, you may need help from another person.

Eat or drink 15 g of ‘fast acting’ carbohydrate right away, (15 g glucose tablets or 1 tbsp sugar dissolved in 175 ml water). Glucose tablets are the preferred method of treating lows.

Other quick sugar remedies include:

  • 3/4 cup orange or apple juice or regular soft drink
  • 1 small box of raisins
  • 1 tbsp of honey
  • 3 dextrosols or 6 Lifesavers

Wait 10-15 minutes and recheck blood glucose. You should be feeling better. If you are not feeling better, or your glucose level is still less than 4 mmol/L, repeat 15 g of ‘fast acting’ carbohydrate.

If your next meal is more than an hour away, eat a snack of a starch and protein (cheese and six crackers, half of a peanut butter or meat sandwich).

If the blood glucose is severely low (less than 2.8 mmol/L) and one is conscious:

  • Take 20 g of carbohydrate preferably as glucose tablets.
  • Wait 15 minutes and re-check blood glucose.
  • If you are not feeling better or your glucose level is less than 4 mmol/L, repeat 15g of fast acting carbohydrate.

What is a glucagon kit?

glucagon-kitThis kit is used for emergencies if your blood glucose drops so low that you become unconscious or can’t swallow.

If you are taking medication that increases your insulin levels, or if you take insulin injections, you are at risk for low blood glucose (hypoglycemia). You may need a Glucagon Kit for hypoglycemic emergencies. Glucagon is a hormone that increases glucose levels rapidly. If your blood glucose drops so low that you become unconscious or can’t swallow, you may need an injection of Glucagon. If you take insulin or have ever passed out due to low blood glucose ask your doctor about a prescription. If you are already using Glucagon, set time aside to review the procedure with your friends, family and co-workers.


A rise in blood glucose levels can be caused by:

An increase in the amount and/or type of carbohydrates you eat
Most foods, except fats and meats, contain carbohydrates. When you eat foods that have a high concentration of carbohydrates per serving, or you have an increased amount of your usual foods, your blood glucose will rise.

Glucose released by the liver overnight
Your body requires glucose 24 hours a day, seven days a week. Your liver stores glucose and releases it during the night. With type 2 diabetes, your liver can sometimes release too much glucose. This explains why your glucose may be higher in the morning than before you went to bed – even when you’ve had nothing to eat.

An illness can pose special problems for people who have diabetes. Illness is a stress on your body that can cause your blood glucose levels to go up. Even a minor illness such as a cold, flu or infection can raise your blood glucose level.

Emotional stress caused by excitement, anger, worry and fear can cause an increase in blood glucose.

Not enough medication
When you have less medication than normal (a missed dose for example) or the medication you are taking is not effective enough, blood glucose levels will rise.

You may have experienced some of the signs of high blood glucose since you were diagnosed, these include: thirst, frequent urination, blurry vision, dry or itchy skin, hunger, feeling tired, unexplained weight loss, cuts that won’t heal, numbness or tingling in hands and feet.

TIP: Sometimes there are no symptoms when your blood glucose is high. The only way you can be sure is to check your blood glucose.


Track your results

When you monitor your blood glucose levels, track them in a diary or blood glucose log. Talk with your diabetes team about interpreting your results. When looking at glucose readings, it is patterns and trends that are important – not an occasional reading that is out of the ordinary.

With the information from your blood glucose patterns, adjustments to your food, activity or medications can be made to make sure you are achieving as healthy glucose control as possible.

Discuss your individual goals with your diabetes team. According to the Diabetes Association 2019 Clinical Practice Guidelines for the prevention and management of diabetes, the target range for most individuals is noted at right.

It is helpful if you test your blood glucose at a variety of times during the day, both pre and post meals. It is quite possible for your morning, pre-breakfast glucose to be in the target range, and your two-hour post lunch reading to be high. Patterned glucose readings, such as several pre-supper readings in a week, provide a more complete picture than one individual reading.

More frequent testing may be necessary if the blood glucose is not well controlled, if hypoglycemia (low blood glucose) occurs, or in unusual situations such as travel, illness or exercise.

Speak with your educator about which pattern of monitoring you should follow.

Verify your meter’s accuracy once a year. Do a glucose reading from your finger at the same time a lab sample is drawn, then have the meter result recorded directly on the lab requisition. When the results from the lab test are reported, the difference should be no more than 20 percent.

Blood glucose level targets

Before meals
4.0-7.0 mmol/L for most people with diabetes

Two hours after eating (from the start of eating)
5.0-10.0 mmol/L or 5.0-8.0 mmol/L if A1C target of 7 is not being met

What is an A1C?

Your Hemoglobin A1C is a measurement of your average blood glucose control for the last two to three months.

About 50 percent of the value comes from the last 30 days.

Your A1C should be measured every three months, if your blood glucose targets are not being met or if you are making changes to your diabetes management.

Your A1C is an important measurement of your diabetes control, as well as before meal and after meal blood glucose levels.

You may also like