Product Review: Taking a Deep Look at the Eversense CGM After a 3 Month Trial Run
By, Gary Scheiner MS, CDE
When I took marketing courses as an undergrad (believe it or not, my first job out of college was as a copywriter at an ad agency), I learned two things about new products:
- Their chances for long-term success are slim.
- If they’re going to succeed, they had better offer something a whole lot better than what’s currently out there.
I first learned about the Eversense implanted continuous glucose sensor (from startup company: Senseonics) while attending the American Association of Diabetes Educators annual conference three years ago. My first impression was less than stellar.
Why would anyone want to have something surgically implanted when we have CGM systems that work perfectly fine without the need for an outpatient surgical procedure every three months? Then I dug into the details. Some things about it impressed me, so I decided to give it a try.
How does Eversense CGM work?
The sensor itself is the size of a skinny caplet. It uses optical/fluorescence technology to measure glucose concentrations and emit a very short-distance signal reflecting the measurement.
To insert the sensor, a trained/certified physician, nurse practitioner or physician’s assistant makes a small incision (about ½ inch) on the back of the arm and uses a tool to place the sensor below the skin. It is possible to wear the sensor on other parts of the body, but at this point the FDA has only approved the back of the arm.
After the insertion, special adhesive strips are placed on the skin just long enough for the incision to heal, which takes about a day.
Because the signal emitted by the sensor only travels a very short distance, a transmitter must be taped to the skin directly over the sensor. The transmitter essentially “amplifies” the sensor signal using Bluetooth technology so that it can be picked up by a cellphone. The transmitter also has some intelligence to it – it can vibrate to let the user know if their glucose level has gone above or below user-set targets.
Once the signal reaches the phone, an app displays the user’s glucose in graphic and statistical form, with historical data available right on-screen. Reports can be generated to share with healthcare providers.
The app comes equipped with the usual array of alarms and alerts letting the user know when glucose levels are trending out of a desired range. The data generated by Eversense is stored in the cloud, so reports can be viewed on a smart watch and shared with loved ones
Pros of the Eversence CGM:
THE APPEAL:
> I suppose the main advantage afforded by Eversense is that there is no need to “change” the sensor on a regular basis, as is the case with all other CGM systems.
In the US, the sensor is approved for 3 months of continuous use, and the European version (scheduled to hit the US market in the next year or two) is good for 6 months.
What this means is that there are no “warmup” times other than the day the sensor is first inserted. I believe this type of true continuity makes Eversense an ideal CGM to use with hybrid closed loop systems which depend on sensor data to function.
> If you’re concerned about having something in your body, don’t be. The sensor is made of bio-compatible materials that cause no allergic or immunologic responses. And because there is no discernable metal in the sensor, it need not be removed during standard medical procedures.
> The accuracy of the sensor is quite good. Its MARD (mean absolute relative difference) compared to laboratory glucose values is just below 9%, which makes it the most accurate CGM on the market. By comparison, Dexcom is just below 10%; Medtronic and Abbott Libre remain in double-digits.
> The smart transmitter is also appealing. I don’t usually have my phone on me when running or playing basketball, so I found the high/low vibrations produced by the transmitter to be useful.
> The silicone-based transmitter adhesive holds it in place very nicely with a very low incidence of skin irritation. And by the way, the transmitter can be removed and replaced without losing any data.
> The Eversense cellphone app is relatively easy to use. It generates useful reports and allows for variable alert settings. Being able to see up to 90 days’ historical data, including trend graphs, right on screen is unique to this system.
Cons of the Eversence CGM:
THE CHALLENGES:
So why isn’t everyone using Eversense? It has its downsides
The Sensor:
> The sensor insertion procedure requires an office visit and healing time. It’s not a painful experience (numbing agents are used), but it is inconvenient and leaves a small scar. And it has to be repeated every three months.
Calibrations Required:
> The system requires fingerstick calibrations at least twice daily, and the calibrations can only be performed when the glucose is in a steady-state. The app generates calibration reminder alerts twice daily regardless of whether a calibration was recently performed. That’s annoying!
The Transmitter:
> The need to have a transmitter on the skin negates many of the benefits of the implanted sensor. Keeping the transmitter working requires a daily ritual that takes about ten minutes. You must remove the transmitter from the skin, remove the adhesive from the transmitter, charge it, re-apply the adhesive, and use a locator guide on the app to re-place it directly over the sensor.
The App:
> Personally, I found the glucose trend graph displays on the app to be visually awkward. They could have taken a lesson from the other CGM manufacturers in designing their display screens. While the reports are simple to generate, there is no “overlay” report for quick detection of patterns and establishing cause/effect relationships. I also found the app to drain my cellphone battery faster than the apps for other CGM systems. And for some reason, the app does not allow the user to set their high/low alerts within their target glucose range–something the software engineers need to fix asap.
The No’s:
> In many instances, there is no medical coverage for Eversense. Senseonics is working on this, but they still lack the (near) universal coverage of other CGM systems. Discounts are available for those who lack insurance coverage. The system is not yet approved for use among children. It can be prescribed off-label for kids, but this may further limit insurance coverage. And at this time, there is no inter-operability with any pumps or hybrid closed loop systems. This will likely change, but for the time being, Eversense does not feed data into anything but its own app.
THE FINAL SCORE:
It was that last point that led me to discontinue use of Eversense once my three-months was up.
As a user and advocate of the do-it-yourself Loop hybrid closed loop system, I must use the Dexcom CGM to keep the hybrid closed loop humming along. Were it not for this and the daily calibrations & transmitter maintenance rituals, I would probably still be using Eversense. The accuracy was excellent, and it truly exemplifies the CONTINUOUS aspect of a continuous glucose monitor.
As a first-generation medical device, I feel that Eversense is head-and-shoulders better than anything that preceded it.
Unfortunately, other CGM systems are already on their 4th, 5th and 6th generations, which means that they have already worked out most of the bugs and shortcomings that plagued their first-generation products. The folks at Senseonics are already hinting at next-gen features such as longer sensor life, even better accuracy, fewer calibrations, and a smaller transmitter that requires far less maintenance. In other words, more upside and less burden on the user.
Will it succeed long term? I don’t know, but I hope it does. Competition is a good thing for keeping all the players on their toes and constantly looking to improve.
And that’s a major benefit for us all
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