Glucose Monitor : Which Technology to Choose?

There are two technologies available for monitoring glucose levels: one measures glucose levels in the blood using a glucose meter, while the other reads glucose levels in the interstitial fluids using a continuous glucose monitoring (CGM) system. So, how do you choose?

Glucose meters, the traditional method

Glucose (or blood sugar) meters have been in use since the 1980s. While there are several models on the market, they all work the same way. You use the meter by inserting a test strip into the device, then pricking the tip of your finger with a lancet to extract a drop of blood. Next, you place the drop of blood on the test strip, and in a matter of seconds, the glucose in the blood reacts with a chemical product in the strip and the reading is displayed on the device.

Glucose meters have evolved over the years and are now smaller and easier to use. They can store readings in the device’s memory and track blood sugar trends. Some can even be paired with your smartphone via an app that lets you add notes to provide context for your readings and help make them easier to interpret. Most glucose meters also offer an option to produce reports to help interpret glucose readings. However, the amount of data is limited, since the user only measures their blood sugar levels a few times a day.

CGM, the new kid on the block

Continuous glucose monitoring (CGM) appeared on the scene in the early 2000s. There are currently two types of CGM available:

• Intermittently scanned continuous glucose monitoring (isCGM) and
• Real-time continuous glucose monitoring (rtCGM)

Both types of CGM use a sensor fixed to the surface of the skin to measure blood sugar levels in the interstitial fluid (around the cells under the skin). An applicator is used to apply   the sensor to the arm or abdomen, depending on the device, pushing the tiny wire it contains through the skin and into the interstitial fluid. The sensor remains in place for 10 to 14 days, depending on the product, allowing it to continuously monitor glucose levels in the interstitial fluid. The sensor records the readings, which are then transferred to a display device on which the person can see their glucose level.

What is the difference between isCGM and rtCGM?

With isCGM, the sensor is not a transmitter, and it therefore cannot automatically transmit information to the receiver. The person must hold the receiver just over the sensor (this is known as “scanning” the sensor) to read the results saved on it. The sensor can save and store up to eight hours of data, which means it is crucial to scan it at least once every eight hours, so no data is lost. The receiver may be a smartphone or a compatible blood glucose meter.

With rtCGM, data is automatically transmitted to the receiver without the user having to take any action, because the sensor is linked to a transmitter. Most of the time, a smartphone is used as the receiver. However it is also possible to obtain a receiver from the manufacturer.

What are the advantages of CGM compared to a traditional glucose meter?

With a glucose meter, each reading gives only a snapshot of your blood sugar levels at a specific moment in the day. Even if your levels are normal at the time of the reading, they may still be too high or too low at other times of the day.

Continuous glucose monitoring (both intermittently scanned and real-time) gives a much more detailed picture of how your glucose levels fluctuate, as it monitors them continuously throughout the day. The reports produced by these devices display the data in the form of curves that allow you to visualize how glucose levels vary during the day. These curves are helpful for understanding the impact of medication and other factors like food intake or physical activity on glucose levels, making it easier to make decisions to improve treatment or lifestyle habits as needed.

CGM systems have alarms and alerts that can sound when blood sugar is too low or when it drops suddenly and can warn you when there is a risk of hypoglycemia if nothing is done to correct the situation. These alarms help you to take rapid, appropriate action to prevent complications from arising. Glucose meters, on the other hand, can only check blood sugar levels at the time the reading is taken.

Who should monitor their blood sugar levels?

Anyone living with diabetes should monitor their blood glucose levels periodically to ensure that their treatment is working properly, achieve satisfactory control over the disease, and reduce the risk of complications.

The frequency of testing varies greatly depending on the type of diabetes and treatment. For example, most people with type 2 diabetes who have a low risk of hypoglycemia (low blood glucose) do not need to test their blood glucose every day. In contrast, people with type 1 diabetes who inject insulin 3 or 4 times a day usually need to test their blood glucose several times a day.

Other people may also be advised by their healthcare provider to monitor their glucose levels, for example those who often experience hypoglycemic episodes, who are pregnant, or who are taking medication that may affect the way their body metabolizes glucose.

How do I choose the best system for me?

CGS is primarily recommended for people who need to check their glucose levels several times a day because they inject insulin. Because these devices are expensive, provincial insurance plans only cover them for certain people who meet strict criteria. Private insurance coverage for these devices varies by plan. Check with your insurer or pharmacist for more information.

For people with diabetes who do not inject insulin, traditional glucose meters are the preferred option. When choosing a device, you should consider the device’s features (types of reports, display language, smartphone pairing, etc.) and ease of use, e.g., font size, screen brightness, and how easy it is to handle test strips. Your pharmacist can help you choose the best device to suit your needs. The cost of test strips is usually covered by prescription drug insurance plans, with some restrictions depending on the treatment.

Got questions about glucose monitoring? Consult your pharmacist. They can help!