All About Medtronics Guardian Connect Continuous Glucose Monitor (CGM)

One of the big names in diabetes technology is Medtronic Diabetes, the pharma giant that has offered insulin pumps and continuous glucose monitors (CGM) longer than any other company. Those products are now typically bundled together, yet many people either don’t know or tend to forget that Medtronic does, in fact, sell a stand-alone CGM.

The device is known as the Medtronic Minimed Guardian Connect, a smartphone- compatible CGM that does not require a separate handheld receiver to view glucose data, and does not require you to use a Medtronic Minimed insulin pump. It is a competitor to the popular Dexcom G6 and Abbott FreeStyle Libre CGM products, as well as the Eversense implantable CGM by Senseonics.

There is a new iteration currently under review by the Food and Drug Administration (FDA) that may be available by the end of 2021, but for now, the current Minimed Guardian Connect is the only CGM device available from Medtronic — whether you buy it with or without one of their insulin pumps.

What is the Medtronic Guardian Connect?

Here’s a rundown of the stand-alone system that Medtronic recently made available in the United States. Note that functions vary in overseas versions of this product, so always make sure to check that any information you’re reading online applies to your particular country.

Sensors. The Guardian 3 sensor is shaped like a seashell, and although it has an adhesive on the back of the sensor, many users find they need a patch or overtape to keep it in place. The sensors come in boxes of five, and each sensor is approved for 7 days of wear. Since 2018 it’s been FDA-cleared for wear on the upper arm along with the abdomen.

Auto-inserter. You attach the sensor to your body using a dark green plastic one-button insertion device. You place the inserter on top of the sensor to lock it inside the device, then place it over your skin, press down and push the button on the side to insert the sensor. Then you just pull up to release the inserter base. Watch this helpful YouTube video explaining the insertion device and process more fully.

Transmitter. At the heart of this Guardian Connect stand-alone CGM system is a transmitter. It is also seashell-shaped and has built-in Bluetooth capability that allows it to beam glucose data directly to your smartphone every 5 minutes. The transmitter is rechargeable and needs to be charged every 6 days using a proprietary Guardian 3 Link transmitter charger. The transmitter has a 12-month warranty.

No dedicated receiver. The Guardian Connect does not come with a receiver device, but instead talks directly to a smartphone. So, clearly you need a smartphone to use it.

Not pump-connected. Although this stand-alone CGM is basically is the same base product as those combined with their insulin pumps (Minimed 630G and 770G), the transmitter uses different connectivity tech (Bluetooth), so you cannot connect it with a Medtronic insulin pump that you may have purchased separately. Medtronic is working to develop next-generation versions of all its devices that will allow for direct data-sharing using Bluetooth connectivity.

No dosing decisions. Of all the CGM devices currently on the market, Medtronic remains the only one that is not designated by the FDA as a “therapeutic CGM,” and therefore cleared for users to make insulin dosing or treatment decisions from the data. Competing products are approved for that use, and therefore don’t require that you do fingerstick glucose tests to calibrate the system. With Medtronic’s CGM, the FDA still says that at least two daily calibrations are required and recommended.

Not for young kids. This stand-alone CGM is only FDA-cleared for users ages 14 to 75. While the company has done pediatric clinical studies going down to 3 years old, Guardian Connect has not yet been approved for those younger ages. What’s notable is that their latest pump-CGM model (MiniMed 770G) is cleared for use in children as young as 2 years old, but the same CGM sensor in a stand- alone version is not. Why? It appears to come down to Medtronic not doing the necessary clinical trials and legwork to get the expanded labeling for its stand-alone system.

Water-friendly. The Guardian Connect transmitter and sensor can be used when showering or swimming, safe for submersion up to 7.5 feet for 10-minute periods.

How accurate is it?

The standard measurement of CGM performance is known as the mean absolute relative difference (MARD). With this measure, the lower the number, the better the accuracy.

Medtronic reports that the Guardan 3 sensor Connect CGM has accuracy in the 9 to 11 percent range (not too far off from Dexcom and the Abbott FreeStyle Libre,). Interestingly, Medtronic says its clinical data shows that accuracy is actually better when the sensor is worn on the arm versus the abdomen.

Medtronic data also shows that without predictive alerts turned on, it has a 90.5 percent hypoglycemia detection rate (when worn on the abdomen). With predictive alerts turned on and set at 30 minutes before a low, the Guardian Connect system has a 98.5 percent hypo detection rate when worn on the abdomen.

Medtronic’s mobile apps

Guardian Connect CGM app. The Guardian Connect mobile app is free. At launch, it initially worked only with compatible iOS devices, but as of summer 2020 it also works with Android devices. You can see a full list of compatible devices here.

Data display. Like most CGMs, it displays past glucose data during the previous 3, 6, 12, or 24 hours. You can manually log your insulin, food, exercise, blood sugar readings and any notes you may need to go along with that health data.

Touchscreen. In true smartphone form, you can use your finger to trace CGM data lines, and expand or contract the view for whatever the glucose period of time you’re looking at.

Customizable alerts. You can set a predictive alert for any timeframe you wish, from 10 minutes to 60 minutes in advance of a predicted low or high blood sugar. You can also program different glucose thresholds and alerts for different times of day (i.e. day versus night, or any other two periods of the user’s choosing).

Nighttime adjustable volume. The Guardian Connect system has a “Max Volume at Night” feature, which allows for even more alert personalization. This is especially helpful for people who may sleep through their CGM alerts at night and want a louder alert for critical situations like impending low blood sugars.

Smartwatch connectivity. If you use an Apple Watch, you can get alerts and other status notifications right on the watch face. Additional Apple Watch features, such as viewing current sensor glucose level, are planned for future versions of the Guardian Connect app.

Sugar.IQ. This is a separate mobile app that Guardian Connect CGM users have “exclusive access” to. It’s the IBM Watson app that Medtronic has been talking about for a few years now, that remains under development with no set date for broad commercial launch.

CareLink data platform

Like all diabetes tech products from Medtronic, the Guardian Connect CGM communicates with their CareLink software platform. The transmitter talks to the smartphone, which shares data to the Guardian Connect app and then to CareLink via the Internet. From there, you can view your CGM data online through the CareLink Connect portal.

You can also set up an option to send free text message notifications for high and low glucose alerts to caregivers, as well as other CGM notifications. As many as five people can have this direct data-sharing access.

What does it cost?

Medtronic’s marketing people say this Guardian Connect starts at only $50 a month, which is the “lowest cost of any personal CGM system.” However, that’s a bit misleading as this calculation is based off typical patient responsibility for 20 percent co-insurance coverage.

The Guardian Connect CGM requires a prescription from a healthcare professional. It is available for purchase directly from Medtronic Diabetes or through third- party supply companies like Edgepark, Caremark CVS, Solara, etc.

You can contact Medtronic directly to start the process for purchasing this CGM technology.

For those without insurance who are concerned about being able to afford a CGM, Medtronic offers a “CGM Access Discount” program, that brings the costs down to $900 per year for the Guardian Connect sensors and transmitter costs, or as low as $75 a month for those who are eligible.

What users say

Overall, Medtronic Guardian CGM reviews are middle-of-the-road. Most complaints are aimed at the company itself, based on its aggressive marketing practices and reputation for poor customer service. At the Trustpilot review site, Medtronic gets a “poor” ranking average of 2 out of 5 stars.

When it comes to the Guardian Connect CGM product specifically, a common complaint is about the “eggshell” shape of the sensor that makes it easy to flop off the skin, so users often have to employ a large amount of tape to keep it in place.

Accuracy complaints are also common. One reviewer wrote, “Medtronic CGM is horribly inaccurate. It reminds me of the test strips in the 80s that turned different colors to give you a ball park blood sugar. It’s useless. Wakes me up constantly telling me my blood sugar is low when it is in normal range. You are so far behind other companies. If I wasn’t stuck with you because of my insurance, I would definitely go to another company.”

Another user at Integrated Diabetes Services writes, “These sensors are complete garbage. I can’t count the number of times they fail, lose connection, ask for calibration. I don’t recommend wasting your time trying to get these to work. I’ve always used Medtronic products, but trash is trash.”

This YouTube review is more positive, noting better accuracy when there isn’t a lot of blood sugar fluctuation. The reviewer noted that it has potential, but that this product’s data-sharing capabilities still are not up to par when compared to competing devices.

Other CGM options

There are several other CGM systems on the market, that all essentially do the same thing in continuously monitoring glucose data:

• Dexcom G6. This is the market-leading “traditional” CGM device with a sensor and transmitter design, providing automatic continuous results every few minutes. You insert a small oval-shaped unit onto your body that houses both the sensor and transmitter. Each G6 sensor is labeled to last up to 10 days, while the transmitter portion has a 90-day battery life and is used with each new sensor until it runs empty. The G6 also offers advanced alert and alarm options, like “Urgent Low,” “Urgent Low Soon,” “Rise Rate” and “Fall Rate.” This CGM currently integrates with insulin pumps, including the Omnipod and Tandem t: slim X2. Dexcom G6 is approved for use in people with diabetes ages 2 years and up.
• Abbott FreeStyle Libre. This is a “flash glucose monitor” that consists of a little white circular sensor worn on your upper arm. You have to manually scan the sensor each time you want a reading, using a handheld receiver or smartphone app. The latest Libre 2 version offers 14-day wear and optional alerts for low and high glucose levels. The FDA has approved this device for kids as young as 4 years old.
• Eversense by Senseonics. This is a tiny sensor that needs to be surgically implanted under the skin in your upper arm. You wear a black oval transmitter over the insertion spot on your arm, which streams glucose data continuously to your smartphone. This requires a doctor’s office visit to insert and remove each sensor, and some people find that they incur small scars on their arm from the procedure. This long-term option is approved for 90-day wear in the United States and 180-day wear in Europe. It is currently labeled for users ages 18 and up.

Bottom line

Overall, Medtronic’s decision to sell a stand-alone Guardian Connect CGM was a positive move that offered more options for those looking for a continuous monitoring system, but who aren’t using an insulin pump.

The device could be better designed and more user-friendly, and many users say they want more reliable and accurate readings, but there is hope with future CGM technology coming from Medtronic Diabetes in 2021 or 2022.

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