Checking your own blood glucose (self-monitoring) is one of the best ways to know how well your diabetes treatment plan is working. It is also an opportunity for you to take control of your diabetes by providing useful information such as understanding how diet and exercise, illness and stress affect your blood sugar levels. Most importantly it can help you identify blood sugar levels that are dangerously high or low.
Who Should Test Their Blood Glucose
Talk to your doctor about whether you should be checking your blood glucose. People that may benefit from checking blood glucose include those:
- Taking insulin
- Taking medications that put you at risk of low blood sugars
- That are pregnant
- Having a hard time controlling blood glucose levels
- Who are eager to participate in decisions about their health
When to Test Your Blood Glucose
Your doctor or diabetes educator will advise you on how often you should check your blood glucose level. How often you need to test often depends on individual circumstances such as:
- Type of diabetes
- Type of medication
- How well controlled your blood sugars are
- How often you experience hypoglycemia
- If you experience hypoglycemia unawareness
- Job requirements
- If you are feeling sick
Type 1 Diabetes
For people with Type 1 diabetes, checking your blood glucose is an essential daily activity. Testing is usually required at least three times a day. You may be asked to check before and after certain meals, before and after exercise, before bed, and occasionally during the night. You may also need to check your blood glucose level more often if you are ill, change your daily routine or begin a new medication.
Type 2 Diabetes
For people with Type 2 diabetes, not taking insulin, how often you will be asked to test depends on the type of diabetes medication you take, how well it is working and your risk of low blood sugars. If you are taking medication that is not likely to cause low blood sugars and you are keeping your blood sugars in a healthy range, frequent testing is not necessary.
In those with Type 2 diabetes on once-daily insulin, testing at least once a day at varying times of the day is usually recommended.
If you need to take insulin more than once a day, self-monitoring should be used as an essential part of diabetes self-management and is usually required at least 3 times per day. These tests should include before and after meal testing as recommended by your doctor or educator.
Use the tool provided by the Canadian Diabetes Association to determine the recommended self-monitoring frequency for you.
How to Test Your Blood Glucose
All blood glucose meters are slightly different. Refer to the manual that came with your meter for specific instructions.
- After washing your hands, insert a test strip into your blood glucose meter.
- Using the lancing device, prick the side of your fingertip* to get a drop of blood.
- Touch and hold the edge of the test strip to the drop of blood, and wait for the result.
- Your blood glucose level will appear on the meter’s display.
*Some meters allow you to use your forearm, thigh or fleshy part of your hand in place of your fingertip (for checking before meals only).
What Are the Target Ranges?
Blood glucose targets are individualized based on:
- How long you have had diabetes
- If you have other medical conditions
- Complications from diabetes
- Hypoglycemia unawareness
- Other individual considerations
For many people who have diabetes, target levels are:
- Before meals — between 4 and 7 mmol/L
- Two hours after meals — between 5 and 10 mmol/L
What Do My Results Mean?
Record your blood glucose results and review them to see how food, activity and stress affect your blood glucose. You can use a chart such as this for recording.
Check to see if your level is too high or too low several days in a row at about the same time. If the same thing keeps happening, it might be time to change your plan. Work with your doctor or diabetes educator to learn how to interpret your results and how to improve them. This process takes time and patience.
Keep in mind that blood glucose results often trigger negative feelings about having diabetes. Blood glucose numbers can leave you upset, confused, frustrated, angry, or down. Remind yourself that your blood glucose level is a way to track how well your diabetes care plan is working. It is not a judgment of your abilities or of you as a person.
Other Types of Self-Monitoring
Urine checks for glucose are not as accurate as blood glucose checks and should only be used when blood testing is impossible.
Ketone testing is recommended for all individuals with Type 1 diabetes when you are ill, when your pre-meal blood glucose levels are >14.0 mmol/L, or when symptoms of diabetic ketoacidosis (DKA), such as nausea, vomiting or abdominal pain, are present. Ketone strips, which test for ketones in your urine, can be purchased at your local pharmacy. Blood ketone meters and strips are also available for more accurate or frequent testing. Speak to your doctor or diabetes educator to ensure you have a plan for sick days or for when ketones are present in your blood or urine.
Continuous glucose monitoring systems (CGMSs) have been shown to assist with optimal blood glucose control and to reduce the severity and frequency of low blood sugars. They are not a replacement for blood glucose testing because they still require a blood glucose test to allow the systems to operate properly. CGMSs measure glucose levels in the tissues of the body, rather than in blood. A CGMS device displays glucose levels and provides trend alerts and alarm notifications when the glucose level is above or below a specified level. Continuous glucose monitoring (CGM) technology requires a sensor that is inserted just underneath the skin, an attached transmitter and, a display unit (which may be a standalone unit or be integrated into an insulin pump).