The person who was trialling this has written an update of their experiences with it (mainly relating to cycling and exercise). I've taken this from his update on Strava. It sounds like he had issues familiar to all who have used CGM's. It's quite a comprehensive write up and is just his opinion. Thanks to Peter for sharing this:
"As some of you here expressed interest when I started using/testing the Eversense implanted CGM sensor I thought I's share some experiences (cycling/training related) here now that the three months are up and the sensor is no longer under my skin.
Before I start I just wish to state that what I am sharing here is my thoughts on how the Eversense sensor works when training/during physical activity. This was one of my main motivators for partaking in the test. I was hoping that it would be able to help my in my training, as I felt that in the rest of my diabetic life I was quite happy with the tools I was already using. But I am humble before the fact that this is a bit of a "luxurious" way of looking at the system. After all it is not a training tool, but a system for monitoring glucose levels. And as such it may have huge benefits for users with a different set of problems and goals.
The insertion of the sensor under the skin and subsequent "wearing" of it was totally hassle free. To someone the thought of having computer chips under your skin might be alarming but I do not have any issues with that. The heart of the system is the sensor under your skin, but for it to do anything sensible it needs the transmitter on the other side of the skin to function. The transmitter is actually what feeds the sensor energy (The same way wireless phone chargers work). So you still need something attached to you skin: The transmitter, which is taped on to your arm using special adhesive pads. Worth noting is that this is the only insertion point available to the system. It does nor work with abdomen, thigh, back etc.
I found the adhesive pad to work really well even when moving/sweating. Remember that I was using the first version of the transmitter, lovingly refereed to as "the brick", which is quite bulky. There is a new version underway which is a lot sleeker, lighter and also waterproof. The fact that the current transmitter is not waterproof was not problem for me. I used it on really wet rides where I was completely soaked without problem. If your into triathlon there will be problems though.
I did actually drop the transmitter once (
https://www.strava.com/activities/656567050): Had to bunny hop onto the pavement when a tricky traffic situation occurred. As I hopped down again, doing maybe 20 km/h the transmitter came flying and bounced over the asphalt at least 15 meters. I thought for sure I had killed it, but It just carried on as nothing had happened. (In fairness the ride took place after a swim in the ocean (remember: not waterproof, you need to take it off for a swim) and I reused the adhesive pad) So for it's lacking appearance, at least the transmitter is rugged.
The fact that you need to take the transmitter off when showering/swimming etc. was something that at first annoyed me, but as time went on this was one of the things I really came to appreciate with the system. That you can remove the transmitter at any time and be truly "naked" whenever you like.
But what of the actual blood glucose monitoring then? Well I have to say this is where the system, in my experience, fails. At least if you look at it from a training perspective(as describe above). What happens is, going into a ride your levels are accurate (I'm not discussing CGM vs blood glucose lag here. It is not worse, nor better than other CGM system in that regard) but as soon as you start depleting stores and blood glucose goes down it keeps going down regardless of what is happening. And once it is down, it stays down and won't come up even if you have refueled and restored levels.
The best example of this is this ten hour ride (
https://www.strava.com/activities/634254228): After about 1:30 hrs the sensor deemed that I was below 4.0 mmol/L and then kept the levels there for about 4 hrs. Within those 4 hrs there were long periods that levels were reported as LO (below 2.2 mmol/L) The fact that I was doing well above 30 km/h average during this period is proof enough that the readings are completely off. Blood measurements during the same period hand me in the 5.0 - 10.0 range. The ride refereed to here might be seen as a bit extreme in length, but the same pattern is evident in shorter rides.
The effect of this is of course a distrust in the system and the values it presents. This distrust led me to, as time went by, to go training without the transmitter. I felt more secure and performed better when listening to my body and using my experience. The rides when I did wear it I found myself disregarding and being annoyed by alarms and values.
I have my own theories of why this is happening. Once stored glucose is depleted, any glucose you add will not end up in the interstitial fluid (where the measurement is taken) but it will go straight into your thighs. Perhaps the light-based measuring technique used has a limitation here, perhaps the algorithm and its sample rate plays a part. I've provided the data and discussed this with the Eversense team. They give the theory some credit and believe there are things that could be done to address it. Future will tell.
As the system uses your smartphone and an app for presentation and analysis, there is are of course problems with compatibility and Bluetooth connections and all that stuff, but that is better discussed elsewhere. Having a smartphone as a key component of the system is both a blessing and a curse. One thing I would add regarding this here is that, as so many medical companies do, Eversense believe there is a benefit to keep data and broadcast format proprietary and secret.
To me it's just stupid. I have a sensor that broadcasts values via Bluetooth (Does that sound like something you might already have on your bike?) I have a device on my stem capable of reading data from Bluetooth sensors (Again, sounds familiar, right?) Why on earth are they not allowed to talk to each other? Because someone in a boardroom think they can make some extra bucks by obstructing data. But this is another can of worms, and one that sadly is not exclusive to Eversense."
