When I first set eyes on the new Eversense implantable continuous glucose monitor from Senseonics a few years back, I must admit I was not all that impressed. The idea of having a little stick actually implanted into your shoulder and then having to wear a black box taped over it all the time to get readings seemed like a non-starter. But I can now honestly say those compromises should not hold anyone back from this intriguing new system.
I got the Eversense implanted in my arm in San Francisco on December 3, and after a rocky first few days, I've had a quite a good experience with this novel new system just FDA approved this June. I've learned quite a bit, and am excited to share my impressions and user tips with our community.
Eversense System Basics
For those who may be unfamiliar, or need a reminder, the Eversense system from Maryland-based Senseonics is the world's first long-term implantable CGM. It consists of a tiny sensor the size of a small twig that is implanted underneath the skin in the upper arm for 90-day wear (approved for 180 day-wear in Europe); a flat oval black transmitter worn over the insertion site and held in place with an adhesive; and a smartphone app that contains the data monitoring and control functions. We detailed all the specs of the system in our original coverage here.
As a new patient, you get a set of boxes that include the black transmitter and charging cable, and a set of 100 adhesives – 90 white and 10 clear (presumably because the clear ones look nicer, but don't stick as well?)
You also get a welcome folder with big, bold instructions on how to care for the initial incision, and how to set up and use the system. Being a typical go-getter impatient patient, I did not read these very carefully at first -- which makes me a good test case for some of the issues a lot of impatient PWDs will experience out in the real world.
The Eversense Insertion Process
Let's start with the insertion process. Having witnessed a couple of Nexplanon birth control insertions, also a tiny stick implanted in the upper arm, I thought I knew exactly what to expect. However, mine felt a bit more “surgical” than I remembered, with my doctor using a surgical cover sheet and taking extreme caution to keep everything sterilized.
This system is so new that Eversense is sending out a small team of experts to help train endocrinologists on the implantation procedure, taking new patients in groups of threes. As they discussed how my endo should hold the device and where to make the cut, I felt like a guinea pig but in very safe hands.
The insertion itself was very fast and mostly painless -- not more than a moment of sting and discomfort as something moved around under my skin. The wound was taped with steri-strips (that fall off by themselves in a few days) and covered with a waterproof dressing for the first few days. I was instructed not to exercise too hard, raise up my arms vigorously, or swim for a few days thereafter. Luckily, I got the green light to go ahead and do my usual spin class, as long as my arms weren't flailing :)
I did not have any bruising. But yes, I do have a teeny scar on my left shoulder now, just a few centimeters above where I can feel the sensor under the skin. I'm not bothered by that, given that I had a small vaccination pock there already.
After insertion, there is a one-time, 24-hour warmup period before you can place the transmitter over the spot to start getting readings.
What’s Different from Dexcom
Since the biggest question on everyone's mind seems to be how this new system differs from the market-leading Dexcom CGM, let's address that next. Why would I even want to try Eversense?
First off, I'm all about innovation and new D-tools, in case you hadn't noticed! The prospect of a potentially super-accurate sensor that does not need to be reinserted every 10 days became intriguing for sure. Also very intriguing is the idea that this transmitter actually vibrates right on your skin, alleviating the need for so many (beeeeeeeep) audio alarms. There are several companies working on wearable medical devices that use "tactile input" for alerts, which I now believe will be the way of the future. And I sure do like that part!
Overall, some main differences from wearing Dexcom are:
- as noted, the Eversense transmitter VIBRATES right on your skin – allowing you to disable all non-critical audible alarms if desired
- you have to take the transmitter off and charge it for 15 minutes every day, and then re-attach it with a fresh adhesive
- you can take it off and later re-attach it any time you want without wasting anything (other than one adhesive patch)
- there's no need to carry inserters, and the adhesive is always fresh -- but of course you'll be covering the same spot for a full 3 months
- you are encouraged to calibrate often using fingerstick tests
- the look of the app is very big and bold, but also not entirely intuitive, and design-wise it's a little bit jagged (more on that below)
- that black thing on your arm
On that last point, I was happy to begin my trial run in winter, when I'm almost exclusively wearing sweaters and long sleeves -- so I don't have to answer questions too often.
Also note that the vibrations do have unique patterns for each alert -- 3x three short vibes for Low Glucose; 1 long vibe and 2 short vibes for a High; 3 quick vibes and two long vibes for Low Battery; and so on. At first I thought I would have to memorize these patterns, but quickly learned that any vibration is cause to look at the app for a quick view of what's up.
Be a Careful Calibrator
When the team walked me through the setup and how to use the system, one of the first things we had to enter into the app was my daily calibration times. That is, this system REQUIRES two calibrations per day at specific times that you set up in advance. One thing I learned the hard way is how important it is to pick your times and stick to them -- especially in the first week or so when the sensor is "setting in"! If your calibrations are too far apart, or "off" for any reason, you may get wacky readings like I did in the first few days.
I picked 7am and 5pm, as good times for me on a daily basis, but realized only later that I get alerted at 7am on weekends too, which is not my favorite thing (but I'm sticking with it, since it works well for me 5 days a week and you cannot currently set different calibration times for weekends).
What I learned about the Eversense calibrations is:
- Be consistent about calibrating within an hour of the time of your alert!
- As most current CGM users know, you must be careful not to calibrate at times when your BG is changing rapidly -- increasing or decreasing -- as this will confuse the system
- Eversense needs 15 minutes to sync after each calibration, so do not remove the transmitter for charging during this time! Again, that will only confuse the system
- Unlike with Dexcom, which is even FDA approved for use without any calibrations at all, this system benefits from being calibrated often, as long as your BG is relatively stable while calibrating
- Note that after each scheduled calibration, the system will not accept another for a period of two hours, so don't try to "stuff the calibration box," as it were
Living with the Eversense App
I suppose the designers were optimizing for people with compromised vision (?), but the current glucose reading displayed at the top of this app is HUGE. Forget about being discreet; expect your loved ones and anyone within a 6-foot radius to make comments on that number, just screaming off the screen:
On top of that, the look of the ongoing line graph is very jagged, like scary mountain peaks. My 18-year-old daughter gasped when she first saw it, asking, "Isn't that kind of disturbing to look at for someone trying to manage their diabetes?"
I had to admit, I missed the smoother, more subtle lines of the Dexcom app. Also, when you shift your phone from vertical to horizontal orientation, this app does not automatically change view with it. Instead, you have to tap a little frame icon in the corner. And the views of 7, 14, 30 and 90 days of glucose data are not very intuitive. I find it really hard to even see where one day separates from the next, to make sense out of the data.
But there are some things I like very much about the Eversense app:
The app does not often disconnect or lose signal, and if it does, it's easy to fix. Just go to the Menu, and click "Connect." The few times when that didn't work, I simply exited the app altogether and then re-opened it, and it reconnected immediately.
There's a continuously displayed colored bar at the top that shows you plainly in Red, Yellow or Green where you stand in terms of target range.
The clear, easy-to-use Menu includes an Alert History, where you can see records of every High Alert, Low Alert, Transmitter Disconnected or Calibrate Now alert received, with exact day and time. This is super useful for going back over your day or week to retrace your BG steps.
The Event Log is equally clear and easy to navigate, and appears to contain at least a month's worth of detailed info if you continue to scroll back.
The Reports section shows you a Weekly Modal Summary; a Glucose Pie Chart for 1, 7, 14, 30 or 90 days' worth of data; and Glucose Stats Report with the same 1-90 day options, displaying your average, highest and lowest readings, and standard deviation broken in four sections by time of day (midnight to 6am, 6am-noon, noon-6pm, and 6pm-midnight). To email any of these reports to a recipient of your choice, you just click on the Share icon in the upper right of the screen.
If you click into the Share My Data area, you can also send email invitations to your doctors or loved ones to be able to view your continuous stream of data, including alerts and events logged. Remember when we dreamed of having such capabilities? Dexcom made those CGM dreams come true, and it's great to see new systems making data sharing and remote monitoring a real no-brainer.
The Settings area is of course where you control all the basics, from a sub-menu including: Glucose, Daily Calibration, System, Sound Settings, and Temp Profiles. Note that under "Glucose" in this area is where you set your BG target range, and also your High and Low alert levels, which will presumably be a wider spread than your ideal targets. You can also set a Predictive Alert for 10, 20, or 30 minutes in advance of an oncoming Low or High (rapid change rate).
Under Sound Settings, you can choose the ring tones for audible alerts, and also click to "disable all non-critical alerts and notifications." This option makes it so you only get sound alerts if you ignore the transmitter vibration for a High or Low "snooze" period that you choose yourself, from 5 to 30 minutes.
In the Temp Profile area, you can set the audio alerts to sound for only a specified number of time, from 30 minutes to 36 hours. This could be a potential fix if you prefer to have all audio alerts activated overnight only -- setting them to go off only for your 8 hours of sleep time for example -- but be aware that you can't set this to automatically repeat each night. Instead, you'd have to go in manually each evening before bed to activate your 8-hour Temp Profile.
I've opted to "disable all non-critical alerts" 24 hours a day so far, and am amazed at what a difference this makes in quality of life -- no more alarm fatigue!! I hadn't realized how incredibly burnt out I was on all that beeeeeeping noise day and night. It has truly been a gift to free myself of one major source of alarm noise.
Changing Adhesives and Charging
OK, let's talk system maintenance. As noted, the Eversense transmitter needs to be charged every single day for about 15 minutes, and then re-attached to your arm with a fresh adhesive. Yes, this is something you kind of need to plan your day around, otherwise you can easily forget and the system will run out of juice. At first, I tried to be very regimented and take care of this at the same time each morning while showering, but my schedule is pretty variable. On the mornings when I rushed off to the gym, I'd forget about charging often until late that afternoon or evening. Then if it was more convenient for me to charge first thing the next morning, it bothered me that I wasn't getting a full 24 hours on the new adhesive. But that is where you need to have a different mindset: you're not actually wasting a sensor, and you have plenty of adhesives to work with.
Of course you no longer have to carry any inserters or equipment when traveling, other than the charging cable and a small pack of adhesives. I found a perfect little drawstring bag for these supplies.
But the fact that the proprietary cable is so essential worries me a bit -- it's so easy to forget or misplace, especially when you are at the gym often or travel a lot. I really would recommend that Senseonics start offering two in the package to make users' lives easier.
When you're ready to put the transmitter back on your arm, you open the Placement Guide on the app and then peel off the paper front of the adhesive and stick the transmitter to it. Then you peel the large portion of the arm-facing adhesive side and gently press it on your arm so that the transmitter is placed just over the inserted sensor. The Placement Guide indicates whether you've hit the mark or not, with a set of bars indicating Low, Good, or Excellent signal.
Remember, you've got a set of 100 adhesives – 90 regular white and 10 clear ones. No extra medical adhesive wipes are necessary at all, nor do you need any remover wipes to get gunk off afterwards! They go on sticky and come off clean -- yay! But I was able to empirically prove that the clear plastic ones cause more irritation, and seem to peel off faster when you're sweating. So I'm saving those for special occasions.
This adhesives setup has Pros and Cons. On the good side, you're only wearing each Eversense adhesive for 24 hours, so they're always fresh, and for longtime CGM and pump wearers like me, you get to give your belly, back and other spots a break, which is very nice! On the other hand, that single spot on your arm is now going be covered by adhesive for 90 days running. I'm still wondering what shape my skin there will be in at the end of my first sensor's life.
btw, there are Decorative Skins for the Eversense transmitter sold by Pump Peelz. If you use them, be sure to look for the tiny cut-out at the top of the circle that you're meant to remove so you can still see the transmitter mode light. I missed that at first.
A big plus of the Eversense is supposed to be its unprecedented accuracy, even winning out in a 3-way comparison against Dexcom G5 and the Abbott FreeStyle Libre monitor. In my case, I only wore it overlapping with my Dexcom G6 for the first four days, in which the Eversense was still "settling in" and showing some wonky readings. After my G6 sensor needed replacing, I just couldn't face wearing three gadgets all at once (given I'm an OmniPod user). So I can't say exactly how it stacked up to Dexcom one-on-one over time.
But ever since those first 5 days passed, I can say that the readings have been incredibly close to what I get on my fingerstick meter, usually within 15 points!
After I've treated for a High or a Low however, there is definitely still a lag until the system starts to recognize the BG moving back into range. It will continue to vibrate for what seems like a long time after it needs to. This is where vibrations vs. loud beeping alarms are a real plus, yet again.
Pros and Cons of the Eversense CGM
Here's my synopsis of the advantages and disadvantages of this system:
- You can remove the Eversense transmitter for a free arm any time you wish, without wasting much of anything
- The Alert History on the app is very useful for tracking your overall experience/BG control
- Love the very easy data sharing on the app!
- No need to carry inserters or re-insert a sensor
- The daily adhesive stays stuck to the skin really well and comes off clean – with no need for special sticky wipes or remover wipes. You can even pull off the transmitter for a brief time and re-stick with same adhesive if necessary
- You must remove the transmitter every day to charge and change the adhesive. I often forgot about this until late in the day -- plus there's a charging cable to lug around
- You will be wearing adhesive in the exact same spot for three months running, which I worry could eventually cause skin irritation (or at least a big pale patch on my arm)
- I found the system slow to pick up on changes after I'd treated a High or Low (not unlike other CGMs on the market)
My final word for now would be this: Do not opt to use Eversense simply because you are looking for something "easier" than other CGMs available. As noted, this system requires a lot of calibrations and some daily effort, so you have to be committed.
But if you're willing to do the work, it is really cool to be free of ongoing insertions and audible alarms, and the Eversense app is very clear and easy to use.
My BG control has improved! Whether that's from simply focusing on a new toy, or truly a credit to the Eversense system is hard to say. Despite the work required, I am actually enjoying using Eversense. And enjoyment = motivation. So kudos to Senseonics right there.