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Viewing blood sugars with just a quick glance at your wrist is no longer a futuristic dream for people with diabetes.

In fact, wearing a continuous glucose monitor (CGM) sensor that can now beam near-real-time data to a smartwatch is becoming a cornerstone of daily care for many people with diabetes.

However, it’s still a bit haphazard as to which CGM is compatible with which version of iPhone or Android phones, as market leader Dexcom and others scramble to keep up with evolving consumer technology. And those who rely on do-it-yourself (DIY) diabetes tools are always finding new ways to tap into existing technology for personalized data-viewing.

Word is the Apple 7 as well as the Samsung 4 smartwatches could both include glucose sensors, but those are just reports that aren’t substantiated; similar claims have made in years’ past but never materialized.

Here’s a look at how currently available CGM systems from Dexcom, Medtronic, Abbott, and Eversense connect to smartwatches, and some of what we may expect in future diabetes technology worn on the wrist.

We’ve come a long way since the very first diabetes wristwatch concept introduced in 2001: the GlucoWatch G2 Biographer, an early attempt at non-invasive glucose monitoring (meaning it took readings without penetrating the skin). Despite gaining FDA approval at the time, that product unfortunately failed and was discontinued in 2007.

There are many ongoing attempts to create a viable wrist-based non-invasive glucose monitor, but none have taken a foothold to date. (See notes on the K’Watch Glucose product below.)

Today, we are grateful to simply be able to view glucose readings on a mainstream smartwatch that’s not designed specifically for diabetes. Some of the most common models compatible with CGM devices include the Apple Watch, Android Wear, Fitbit (formerly Pebble), and Samsung.

It is critical to understand that it’s not the smartwatch actually monitoring your glucose levels. Rather, for most of the technology currently available, the watch simply acts as a conduit receiving the data from your CGM sensor/transmitter via a smartphone app.

We can credit San Diego-based CGM market leader Dexcom with pioneering the ability to view glucose data on a smartwatch. The company first enabled limited Apple Watch connectivity in April 2015, and later expanded that for all personal use of its G5 model in March 2016 and the G6 model once launched in 2018.

Now, the Dexcom G6 mobile app is compatible with both Apple and Android watches with various watch faces. It displays your current glucose number and arrow trend, as well as graphs for 1-, 3-, 6-, and 24-hour periods.

Anytime you wake up the Apple or Android watch, it syncs with the current CGM data from the app running on your iPhone or Android phone.

We’re still waiting for Dexcom to provide direct-to-watch connectivity, which the company has been promising for years. In early December 2020, Dexcom said during an investor update that direct smartwatch connectivity will be coming with their next-generation G7 model, expected by year-end 2021.

Until then, users still need to use an iPhone or Android phone as a go-between to receive data on the smartwatch and access alerts.

One fun aspect of the Apple Watch is that you can make the Dexcom change the watch face color to reflect your glucose status — red, green, or yellow — to call major attention to your current reading.

You can see this full list of compatible devices for the Dexcom CGM. Remember, just because a phone or watch isn’t initially listed, that doesn’t mean Dexcom isn’t working to add it down the road.

Medtronic is the market leader in insulin pumps and the only company that also makes a CGM, the Guardian Connect. For the most part, they are pushing customers to purchase their combined system, the partially automated Medtronic 670G.

Medtronic doesn’t currently have a real-time data display on Apple or Android smartwatches. But those using the Guardian Connect CGM as a stand-alone product can view push notifications and status alerts on any compatible smartwatch, and the rest of the data on the Medtronic mobile app.

Medtronic had been collaborating with Samsung to develop a watch device for several years, but the company tells DiabetesMine that is no longer in the works.

You can see a full device compatibility list here for Medtronic CGM sensors.

The implantable Eversense CGM from Senseonics is unique in that it does not have its own receiver, but is completely dependent on a smartphone app to function. That means to activate the system, see glucose readings, and receive alerts for high and low blood sugars, you need to use a smartphone.

Eversense is compatible with both Android and iPhones as well as the Apple Watch, according to the company website. We’re told that Android smartwatch connectivity is in development, but there is no timeline on when that might be available.

See the full compatibility list here for more details on which devices work with the Eversense CGM.

This system from Abbott Diabetes Care is known as a “Flash Glucose Monitor” that requires users to manually wave a scanner over the small circular sensor worn on the arm to get a reading. That is true for the Libre 1 and Libre 2 models, but the new version 3 recently launched outside the United States is doing away with that need, making it more competitive with CGMs from Dexcom, Medtronic, and even the implantable Eversense.

In Europe, several DIY tools have emerged that make smartwatch connectivity possible for the FreeStyle Libre, but it’s not yet available through the commercial models that need to be scanned in order to display glucose results.

That may be something Abbott offers when the Libre 3 makes it to the U.S., but so far, there’s no official word on that.

Around 2013, tech-savvy developers and coders began hacking into their diabetes devices and built mobile apps to beam data onto smartphones and watches. This became known as the #WeAreNotWaiting DIY diabetes movement.

The mobile apps they created for data-sharing, including Nightscout and xDrip, actually paved the way for smartwatches and remote connectivity for CGMs.

It began with the popular Pebble Watch, which is now defunct after being acquired by Fitbit. There is now a handful of new Fitbit smartwatches that weave in CGM connectivity, including the Fitbit Versa and Ionic brands.

As noted, numerous developers are chasing the dream of creating a successful non-invasive glucose-tracking watch.

Notable among those is the K’Watch Glucose tracking watch launched in 2018, a year after first grabbing headlines at the big CES (Consumer Electronics Show) in Las Vegas. This doesn’t continuously monitor glucose but does so every time you touch a button on the watch to prompt it to take a measurement.

It’s the creation of the 2016-formed French startup company PKVitality (pronounced PEEKA-Vitality), which brands it as “the first-ever glucose monitoring sensor embedded directly into a wearable device that measures BG levels through your skin.” [Guess they never heard of the now-defunct GlucoWatch?]

This watch “uses microneedles to ‘taste’ fluid just below the skin’s surface and analyze it for glucose or lactic acid.”

Specifically, underneath the watch face, there’s a special proprietary biosensor known as the “K’apsul” made up of tiny microneedles that work to “painlessly penetrate the top layer of skin and analyze interstitial fluid” — which is the same fluid measured by other CGMs.