My experience as a new CGM (Continuous Glucose Monitor) user
I AM NOT A DOCTOR!
(or a nurse, or a PA, Dentist, Psychologist, Social Worker, Chiropractor, or anything of the type. I work on computer networks for a living.)
(This sounds familiar)
I think it's important that I begin here (again) by repeating that I am not a medical professional, nothing in this post (really nothing I say anywhere) should be taken as any sort of medical advice. Go talk to an actual doctor!
That said, here's what I think of my CGM.
I love it.. (end of post).
(Joking, I wouldn't do that to you).
I might get a little long-winded here too, sorry, but I actually have a lot to say about these things.
As mentioned in the post about Ozempic, 6-Ish month ago, my numbers were climbing to the point where we needed to make some more drastic changes to medication, lifestyle, etc. to keep this thing under control. Dr. said "I think you'd qualify for your insurance to pay for a CGM".. I wasn't sure they would, because some insurances (I've heard) will only cover them for insulin dependent people, which I am not yet. But it was worth a try, so he prescribed a Dexcom either g6 or g7, (I don't remember), and it got denied, come to find out my insurance must have a deal with Abbott Laboratories, so they'll only cover their "Libre" CGMs.. Sooo...Attempt #2.. He prescribed the Freestyle Libre 14-day system. The insurance did cover those, and the pharmacy gave me 2 of them (enough for about a month).
My doctor is not a diabetes specialist, if he was, he would have known these were an older model, a hassle to use, and not nearly as good as the 3-plus version that Abbott also makes. I'm glad they only gave me two, because white that sensor worked as intended, it's annoying. You have to tap your phone to it any time you want an update, and it only stores the last 8 hours of data, so if you forget to tap it for more than 8 hours (or forget to tap it at least once in the middle of the night), you get gaps in your graph. Way better than several finger sticks through the day to be sure, but certainly inferior to the more modern sensors.
And a bigger issue with it not communicating via Bluetooth is that, for a time, I was still adjusting to what medication I should be taking alongside my Ozempic, and for a while I was going very low, and without continuous communication, it's not capable of alerting you to a low while you're asleep.
So fast forward a month, and I sent a message to my insurance company to ask if they would cover the Libre 3+ (which uses Bluetooth). They said yes, so I sent the doctor a message asking him to change my prescription going forward. Next time I filled it the pharmacy gave me 6 sensors, 3 months worth.
Hang on now! Back up.. what exactly is a CGM? Here's the 50-cent explanation.
Continuous glucose monitoring involves a wearable sensor, and some sort of device to receive the sensor's readings. Nowadays where pretty much everyone has a smart phone, the newest sensors talk to an app on your phone, and use Bluetooth to continuously update the reading on your app. Other systems might use a dedicated reader device, or some will talk to insulin pumps, etc. Mine just talks to my phone.
With the Libre 3+ sensor, and with most others, you attach a small sensor with a filament that inserts just under your skin using an applicator. The 3+ comes pre-loaded, ready to go, you just unscrew it, slam it against the back of your (preferably shaved, clean, and disinfected) arm and it's inserted and stuck to you for (hopefully) the next 15 days.
You then "start" the sensor by tapping it to the NFC location on your phone, and one hour later (there's a 1-hour "warm up" time you have to wait for), and you'll start getting instant glucose levels delivered to the app.
Once the sensor expires (15 days later in my case), I take it off, and put a new one in the opposite arm.
The Sensor:
The Libre 3+ sensor itself is an incredible little piece of technology. It takes a reading every 60 seconds and sends it to your phone via Bluetooth low energy. It's tiny, the battery in the thing is a teeny little coin cell, and it runs the thing for more than 2 weeks communicating with your phone once every minute. 21600 readings (minus 60 considering the startup time) from this little thing that's not much bigger than an American penny. That's absolutely astonishing.
The Libre app:
It's pretty apparent that the people that developed the sensor are not the same people that developed the app. The Libre sensors are extremely impressive. Their app is very limited, and not well thought out.
What it does: It reads your glucose levels, puts them into a pretty limited functionality graph (You can't even zoom in/out or scroll back and forth, etc.), tells you your sensor life span, if your levels are trending up or down, if you're "in range" or not, and and alarms if your levels go too low or too high. For many people this might be good enough.
But the problems are with what it doesn't do. You can't pinch zoom in and out of the graph, that's something that seems like it should be just an intuitive thing to be able to do.
You can not disable the low alarm, or change the sound. At least in the US version of the app. They must be afraid of getting sued by an over-litigious user, because people in forums say that they can change these things in the non-US versions of the apps.
The Libre app doesn't provide any widgets, so there's no way to view your current glucose without running the app. Nor is there a way to display your current reading to your notification bar, or to the lock screen, or always-on display. Nor can you send the number to a smart watch. These things seem like they should be pretty basic features.
3rd party apps:
Luckily for anyone who is even just a little technically literate, there are some much better options created by some talented people that create their apps and give them away just because they're good people.
Currently I'm using an app called "juggluco" to communicate with my sensors, and feed data to another called "glucodatahandler" to send values to my notification bar, a widget on my home screen, and my lock screen and always-on screen. They also are way more customizable when it comes to alarms. They both allow you to do seemingly simple things like scroll/zoom on your graph, customize alarm sounds, disable alarms (even the very low alarm), etc.
Configuring these is outside of the scope of what I'm going to discuss here, because it will be different for different phones, different sensors, and others have already done that work and published those steps. I'll just say that it was worth the bit of learning curve involved in configuring the 3rd party apps.
There are other options out there also, (gluroo, xdrip+, xdrip4ios, among others)
Juggluco runs in landscape mode only
Things I've learned along the way that I would have liked to know beforehand / Interesting things to know:
Some obvious (or should have been), some not so obvious.
1: They really don't hurt. (or if it does, it's just a little, and it's only twice a month).
Out of probably 20 of these now that I've gone through, only one of them has hurt even a little bit (it felt like it burned mildly for about 30 seconds, not really sure why.) Typically there's zero pain, which is surprising because the needle that is stabbing into your arm is scary looking and bigger than I expected.
2: The needle doesn't stay in you.
The aforementioned big scary looking needle is just used to insert a much smaller filament that stays embedded under your skin. The needle retracts back into the applicator after you install your sensor. I was a bit confused the first time I used one wondering why it wasn't uncomfortable for the entire time I was using it, because at first I thought that there was a big metal needle embedded in my arm.
3: It doesn't measure blood sugar.
Another thing I didn't realize until I started using a CGM and reading more about how they work, is that they don't measure blood sugar. The filament inserts into what they call your "interstitial fluid", which is in the spaces around your cells. The filament sits there, not in a blood vessel. There is a time delay between your blood glucose level, and the glucose in the interstitial fluid, most say around 10-15 minutes.
4: They can be a bit less accurate than a blood test, especially if your glucose level is changing rapidly.
People often complain about the reported numbers being considerably different than a glucose test. I just did a finger stick 10 minutes ago, and my glucometer said 106. Basically right on with the 101 the CGM is reporting right now, so it appears this particular sensor is going to be one of the more accurate ones. Some have been consistently 20 points off one way or the other. It's a good idea to compare every sensor to finger sticks, probably a few times during the life of the sensor.
The point is, this tool is more for watching trends, and getting an overall idea of how food, exercise, and medications affect you throughout the day. It can't do exactly what a "real" blood test does. However hundreds of measurements over the entire day that are 10 minutes delayed and possibly not quite as accurate (but still pretty accurate) are much more useful than one, or a few finger sticks.
Compression lows:
I had no idea this was a thing. If your sensor is in a spot on your arm that you put any weight on during the night, that will push the interstitial fluid away from that area, causing the sensor to read a false low glucose reading (and wake you up with an obnoxious alarm). Then I'd get up and think I needed to drink some juice or something, which was not necessary. I did this a couple times before I realized what was happening. Now before I start a new sensor, I actually lay down as if I'm sleeping on that side, find the right spot that won't get compressed, and am sure to attach the new sensor to that spot.
Time in Range:
You may or may not have heard of the term "Time in Range". It's something I didn't really learn about until after I started using a CGM, because in my opinion it's not really something very realistic to calculate without a CGM.
Juggluco's Statistics page, including a simple Time In Range graph
GDH's Statistics.
And even the Libre app does this much.
Here is a good explanation of what exactly Time In Range is, what goals are recommended, and interestingly, how someone who spends a lot of time out of range on a rollercoaster of potentially dangerous highs and lows can still show an A1c of under 7%, just like someone who keeps their glucose in the recommended range. This seems to me that it might be a better, or at least additional, more modern indicator of how well you're managing your diabetes. (again, not a doctor, just thinking out loud here.)
And here is another article from the American Diabetes Association that I think you should read if this is a concept that you're new to.
Glucose Management Indicator (or GMI):
I've had diabetes for 10+ years, and had never heard of GMI until I started using a CGM. It's an estimate of your average glucose level, calculated from CGM data. The Google AI says it was created to replace the term "estimated A1c", I suppose because it's calculated from a different source, and isn't limited to a strict 3 month date range like an A1c does. It can be calculated based on shorter time periods. When I got my last A1c test, the 90-day GMI estimate number was very close.
Sticky residue on your skin:
The best thing I've found to remove the tape residue is olive oil (or probably baby oil or whatever other, I just always have a bottle of olive oil handy on my countertop). Just put a dab on a paper towel and gently rub and it will come right off. Much less scrubbing than with something like an alcohol pad.
Before using these, I had no idea how bad my levels were really getting during the day.
I'd do a fasting test in the morning, (if I remembered to), and it was almost always 120-130 mg/dL. I had no idea really what was going on after meals, or in the afternoons/evenings. I was never one to remember to test as often as I probably should have been. Doctor says his guess is that I was averaging in the 200s based on my high A1c. This thing make it super easy to know what's happening all day, and more importantly, what is causing that and helps you take steps to take care of it.
Conclusion:
Aside from just being consistent with taking my meds, it's probably the best thing I've done for managing my diabetes. If your insurance will pay for it, you'd be crazy not to take advantage of that. At this point I'd consider buying them out of pocket if I needed to, it's that much of a game-changer.
--Tyson
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