Initiating Continuous Glucose Monitoring

Initiate Continuous Glucose Monitoring (CGM)

The crux of the glycemic control experiment is the use of a continuous glucose monitor.  For years, the standard of care for checking blood glucose throughout the day has been the use of a finger stick, to collect a small amount of blood and place it on a test strip.  The test strip is inserted into a device that reads the glucose and displays it.  This method of glucose is very accurate and is still used by many people with diabetes.  The method is not, however, practical for our experiment and the high degree of accuracy is not necessary to examine glucose trends and get a good idea about which foods are creating the largest spikes in glucose.  So, for the purpose of our experiment, there is a much easier to use device, the Continuous Glucose Monitor that will allow us to determine those trends. Once deployed on the skin, the monitor simply pairs with an application on your mobile phone and allows you to view your blood glucose level all throughout the day.  Again, if you have diabetes and you take medicines for it, your doctor may still prefer for you to use the more accurate finger stick method and our experiment is really intended for patients with lesser forms of insulin resistance like prediabetes and metabolic syndrome.

Obtaining a CGM device

Like many other elements in this book, obtaining a device should be thought of as an opportunity for you to connect more fully with your doctor.   At present, a physician prescription is required to get a CGM device.  In the very near future, this will no longer be the case and CGM devices will be readily available in retail stores and online.  Even now, there are some devices available without a prescription and most of the drug manufacturers that make them are looking for ways to commercialize the use of CGM monitors more broadly.  But in our situation, the need for a prescription is a good chance for us to discuss metabolism with your doctor and let them know what you have in mind.  So, to get started on CGM schedule a meeting with you doctor and ask for a prescription for the device.  Your doctor will likely not object to the use of the device.  Your insurance company on the other hand, might.  If you run into roadblocks either getting the prescription or with the insurance company paying for the device, don’t despair!  The retail cost for the device should only be about $40 and as I have already said, new options are cropping up online every day.  In my program in San Francisco, we use the “Freestyle Libre 3” CGM device.  The device is easy to use, has a good user interface for the mobile phone and has a good price point for situations where insurance falls short.

Obtain a continuous glucose monitoring device from your physician and prepare to start using it.

Setting up your CGM device

The Freestyle Libre 3, the most recent version of this device, comes in a small yellow box which has the monitor inside of a spring-loaded delivery device.  You simply open it and then take off the cap.  Then you hold it to the area where you want to place the device.  Most people wear them on the back of the shoulder over the triceps muscle.  Just press down on the device and you will hear a loud click.  The device will pop out onto the skin and the tiny needle will poke through the upper layer of skin to begin sampling your blood glucose.  You may feel a small pinprick when the device is deployed but this usually goes away quickly. 

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Figure 1:  Freestyle Libre 3 Device Deployed on the Shoulder.

Open the box for your new glucose monitor and follow the instructions inside to apply it to your body.

Downloading the Mobile Application

For this next part, you will need a mobile phone.  If you do not have a mobile phone, check the website for the device you are using.  Many of them offer simplified devices with a blue tooth connection that allow you to read the glucose values from the device without a mobile phone.  Those readers are also available via prescription in most cases.  If you do have a mobile phone, an you are using the Freestyle Libre device, you tap on the app store and look for the Freestyle Libre icon to download the application.  You will need to download the application for the version of Freestyle libre that you have just placed on your skin.  The icon for the Freestyle Libre 3 looks like this: 

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Figure 2:  Freestyle Libre Icon

Be careful because the FreeStyle Libre Monitor has several versions.  The one I am showing here is the newest version.  It has the advantage that you don’t need to hold the phone over the device to scan for blood glucose.  With the FreeStyle Libre 2 device that was necessary.  With the Freestyle Libre 3, the device will passively collect your blood glucose around the clock and display it in the application on your mobile phone.  The Freestyle Libre 2 device works well too and if that is the one that your pharmacy has available, that will work just fine for our purposes.  Just make sure that you download the appropriate Freestyle Libre 2 app when you start using the device.  Once you have downloaded the app on your phone, you will need to make sure that blue tooth is on and then hold the phone close to the device on your skin so that it can recognize the device.  If you have just installed the device on your arm, you will get a prompt that tells you that the new device is recognized and that it will be ready to record blood glucose in the next 60 minutes.  The device needs to sit for an hour before it can start recording.

Download the mobile application for your new device and hold it over the device to start scanning your blood glucose.