A Review of the Dexcom G7 Continuous Glucose Monitor

Jamie Pauls

Since being diagnosed with Type 2 diabetes in 2016, I have searched for the best way to monitor my blood sugar. Finger sticks were tedious at best, and downright brutal at worst. My discovery of the Freestyle Libre sensor, which is a continuous glucose monitor used in conjunction with my iPhone, was truly a game-changer. I wrote about my experiences with Freestyle Libre in the April, 2019 issue of AccessWorld.

For the entire time that I used Freestyle Libre sensors, I paid for them out of pocket. In recent months, the price of the sensors has increased dramatically for me here in the United States. At the same time, my insurance has agreed to pay for Dexcom G7 sensors, so I decided to make the switch. What follows in the subsequent paragraphs are my early thoughts on using the Dexcom system, with a few comparisons between Dexcom and Freestyle. I will say from the outset that I consider Freestyle to be a great product.

When I received my package of three ten-day Dexcom sensors, I downloaded the free Dexcom G7 app from the Apple App Store.

Android users can download the Dexcom G7 app from the Play Store.

Setting up the Dexcom G7 app was simple enough. It did not ask for my age specifically, but rather wanted to know if I was above or below the legal age. Many of the options in the app are not identified as links or buttons, but simply double-tapping activates the element in focus. I had the option to add someone to my account if I wished to do so at this point, which I did not do. On the next screen, my country of residence and language were already selected. Typing my ZIP code and selecting a checkbox to confirm my country of residence was no problem, but this cannot be changed later, so make sure it is correct. On the next screen, I chose to enter my phone number, which was then sent a verification code. I could have chosen to enter my email instead. I then checked a box to agree to all the app’s legal terms. Finally, I entered the verification code sent to my phone number and chose Submit. I then entered my first and last name, date of birth, and email address with no difficulty. The only accessibility issue I ran into was when I entered a password for the app. I had to make several attempts before I could enter it successfully. I then received a text message confirming my account creation. I was then able to add a passkey in Apple Passwords, which is my password manager of choice. I gave the app permission to use my location, and then I agreed to more legal information. Finally, I was given information about how my glucose readings would appear. In my case, this is milligrams per deciliter.

The app then took me through an onboarding tutorial, which was divided into several sections. After completing each section, I had to manually select the next section and complete it. If you do not do that, you will go around in a circle until you move to the next part of the tutorial.

It was finally time for me to apply my first Dexcom G7 sensor. The sensor comes in a round container with a lid that unscrews. There is an easily discernible button on one side of the container. To apply the sensor, do the following:

1. If you have an alcohol wipe, clean the area where you intend to apply the sensor and let the area dry for at least ten seconds.
2. Remove the lid from the sensor and place the open area of the sensor over the spot where you wish to apply it. Dexcom recommends the back of the arm. I recommend that you identify a spot halfway between your shoulder and your elbow. Move past your bicep and then the large bone in the middle of your arm until you find the flat part of the arm where there is plenty of fatty tissue. Place the sensor applicator over the spot and push the button.
3. Remove the sensor applicator by gently pulling it away. Press down on the sensor for about ten seconds, as recommended by Dexcom. Also, run your fingers gently around the area where the adhesive patch can be felt around the perimeter of the sensor to make sure it has stuck completely. Dexcom recommends an overpatch to ensure that the sensor stays in place, but I have not needed to do this as yet. The sensor is about the size of two quarters placed one on top of the other and stays in place for me with no problem.
4. From within the Dexcom app, you must either manually enter a four-digit ID number found on each sensor or scan the applicator for a QR code. The sensor will be recognized and paired with your phone via Bluetooth.

When I applied my first sensor, I manually entered the ID number given to me by my sighted wife. I tried this during the onboarding tutorial and could not get the app to recognize the number. After completing the tutorial, I entered the number again and things worked as they should. When I applied my second sensor, I was able to scan the QR code on the sensor applicator using my phone. The code is found on the opposite side of the button on the applicator. The numbers are toward the top and on the right side of the applicator.

As with the Freestyle Libre sensor, the Dexcom G7 sensor measures the interstitial fluid found in the tissue of your arm rather than actual blood. It is important to place the applicator in a spot where there is plenty of fatty tissue, and it is a good idea to stay well hydrated in order to get accurate readings. The Freestyle 15-day sensors can be used after a one-hour warm-up time, while the ten-day Dexcom sensors can be used after a 30-minute warm-up time. Dexcom now offers 15-day sensors, which also take one hour to warm up before they can be used. Freestyle measures glucose readings every minute, while Dexcom measures every five minutes.

Both products allow you to set alarms to notify you when your readings go above or below set ranges. I find the Dexcom alarms to be less intrusive than the Freestyle alarms in daily use. Both products offer an Apple Watch app to easily check blood glucose levels throughout the day or night if you wear your watch to bed.

In my limited use, I have found the Dexcom G7 continuous glucose monitor to be an excellent product, with easy application, an easy-to-use app, and accurate readings as far as I can tell. It is possible to calibrate your sensor with readings from finger sticks if you choose to do so, but I have not done so personally.

The Bottom Line

Both the Freestyle Libre and Dexcom G7 continuous glucose monitors are excellent products that I can recommend to blind people without any hesitation. Apps for both products are updated regularly. App use and sensor application are definitely accessible to blind people. I am pleased to be able to recommend the Dexcom G7 glucose monitor to any blind person who is considering its use.