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Glucose Monitoring

How can I tell what my Blood Sugar is?

Many varieties of blood glucose monitors are currently available in Canadian pharmacies. They all involve pricking a finger with a needle to get a drop of blood, applying the blood to a testing strip, and having the monitoring machine measure the glucose from the testing strip. There are various "pokers" (lancing devices) on the market. Some are less painful than others, by virtue of an adjustable depth of penetration of the needle (lancet), the fineness of the needle, how much vibration is produced, and so on. The specific type of monitor and lancing device appropriate for you should be discussed with your diabetes educator.

Why should I Monitor?

There are many reasons.

  1. Monitoring shows you what your blood glucose is doing at the best of times, while you are feeling good and in your usual routine. This allows you to interpret the readings under more unusual circumstances. It also lets you to catch any changes in your glucose as time goes by.
  2. It shows you how your blood glucose varies over the course of the day, indicating trends.
  3. It shows you what happens to your blood glucose if there is a change in your diet, such as going out to supper.
  4. It shows you what happens to your blood glucose when there is a change in physical activity, such as playing sports.
  5. It shows you what is happening to your blood glucose in times of illness.
  6. It shows you what happens to your glucose when there is a change in medication (for diabetes or any other illness), and where further changes need to be made.
  7. To let you know if a sensation that you are feeling is due to a glucose that is too low or too high.
  8. If recorded properly, it shows your doctor all of the above so that he can better advise you about your diabetes medications.

The readings are not for the doctor (although they certainly help him/her) - they are mainly for you!

When should I Test my Blood Sugar?

Testing the blood before meals and after offers different information. As a general rule, readings taken before meals indicate how low your glucose can get. Testing after meals shows you how high the blood glucose went, due to the absorption of the food. It should be done 2 hours after eating. Both pre-meal and post-meal testing supply important information. The most common mistake people make in testing is always testing at the same time of day.

Testing once daily at the same time of day (typically before breakfast) does not supply sufficient information about what is happening. You have diabetes 24 hours a day, so you should explore what happens to your blood glucose at various times! Testing times should be rotated.

This doesn't mean blood testing must done many times daily. Consider the information gained from testing, and the disadvantages of testing (including cost, and tenderness of the finger), and strike a balance. Always discuss testing frequency with your doctor. However, unless there are some unusual circumstances, this writer usually recommends:

Type 2 diabetes, not on pills: Test blood twice a week, once before breakfast, and once before supper.

Type 2 diabetes, on pills: Test blood 3 times a week, once before breakfast, once before lunch, and once before supper.

Diabetes on insulin: always discuss with your doctor, as the frequency of testing is highly dependent on the stability of the glucose, the insulin regime you are on, and other factors.

During periods of illness, extra activity, or other unusual events, testing should be more frequent than usual.

What should my Readings be?

This is highly individual. Normal blood glucose is less than 6.1 mmol/L, on an empty stomach (fasting). In people with diabetes, this is often difficult to achieve. In general, we aim for glucoses to be less than 7 mmol/L before meals, and under 10 after meals. Depending on the circumstances, the physician may be aiming for values higher or lower than these, based on age, function, general health, type of medication, and many more variables. There is a saying for pre-meal readings, i.e., "4 to 8, feeling great", but readings of 8 pre-meal are generally too high, in the long run.

Which Meter should I Buy?

Different meters offer different advantages and disadvantages, such as the amount of blood required, memory, whether the data can be transferred to a computer program, and so on.

The bottom line for a meter is its accuracy - if you need to spend money on the lancet and the strip for the meter, be sure that it's giving you accurate readings.

The following meters have excellent accuracy. If you have a meter that is not included in the list below, it should be upgraded.

Tips on getting a Good Drop of Blood for your Strip

Before poking your finger, wash your hands with warm water. Shake your hands below your waist, and, if necessary, milk your finger a few times. However, most of today's meters require less blood, and getting sufficient blood is usually not a problem.


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