The Abbott made Libre Sense continuous glucose monitor/biosensor is one of the first, or the first CGM to be available without a prescription. The sensor is targeted at endurance athletes. It is, to my knowledge only available in Europe.
I have now tested the Libre Sense continuous glucose monitor for 8 subscription periods. So ~4 months total time wearing one.
Process
The way this thing works is you apply it, then you wait an hour. There are two core packages that it comes in: an applicator and the actual sensor. The applicator is essentially sort of a spring that when applied enough pressure to releases and inserts the needle into your body. After applying, the biosensor says that it is “warming up”. Whatever that means. Is my body literally warming this sucker up to cause it to release a signal? I don’t know, but it would be interesting to find out.
Does it Hurt to Apply It?
Applying seems like the wrong word. We’re really installing something onto our body.
But the short answer is no. Of the eight different times I have applied one, I have felt anything at all only twice. And even then it was less than a pin prick I would say. So for me, I have no fear of installing the Libre Sense. I do have fear of pricking my finger for a normal glucose blood test. So for those of you who have done that, I can say that for me it is basically nothing to install it.
Tips
I think that where on your arm you install the sensor is very important. The first couple of times I installed it, I believe it was too high on my arm. I think it was in the tougher part of my arm – in muscle – too high up. The reason I believe this is because the readings were very erratic. Minute by minute the readings would rise and fall. On my third application, I placed it lower on my arm and the readings were smoother.
IMO you should target the lowest/flabbiest part of the back of your arm. Not the “back” of your arm, but the lowest part. The opposite of your bicep.
Exporting Data
The company says that you can export your data if you request their IT team to do so. I have not done this but plan to do so at some point.
Accuracy
Perhaps the most important question is: is this thing accurate?
Short answer: yes.
I have taken 6-8 finger prick blood glucose tests and compared them with Libre Sense comparison tests now. I compared the results from the Libre Sense with calibrated Contour Next and Accu-check glucose meters. I can report that the results are roughly right; they were consistent with the Accu-check meter. The Contour Next seems to run low and be more erratic. The Libre Sense and Accu-check were consistently higher than the Contour Next meter and had more consistent results from test sample to test sample. The Accu-check also appears to take a larger blood sample, which should increase the accuracy of the results, statistically speaking. The test “blood” or sample was well-shaken glucose meter control solution, for those that are wondering.
So yes, based on comparing the results to two glucose meters for diabetics, the results appear to be fairly accurate. The fasting glucose numbers also appear to be consistent with full fasting blood glucose tests I have taken in proper laboratories in the past.
Shipping
Shipping has been quite fast and satisfactory. I’m pretty sure that it has taken two business days every time I have ordered. The last time I ordered was Sunday evening and I had the sensors Wednesday. I looked at the box last time, because I was curious about where these things actually come from. It turns out that they shipped my last sensors from an address in Zurich, where I live. So perhaps they strategically pre-ship the sensors to central locations closer to their customers.
Apple Compatibility
One thing I really want but they don’t offer is an Apple Watch app. It would be so nice to be able to just look at my watch to see my immediate reading. But instead I have to open my phone, then an app. It’s just a single number and an arrow for the recent trend. Even the single number as a complication in Apple Watch would be amazing. Not having an Apple Watch app makes it kind of annoying to look at while running. For biking too, you would have to leave the phone and app open, which just won’t really happen and will quickly drain battery life.
One thing the accompanying app will do is integrate with your workouts if you start an Apple Workout. It will retroactively show the start and end time of your workouts in the app so you can see your glucose readings during your workouts. Maybe you started to feel weak towards the end of a workout and your glucose got really low. You would be able to see that low glucose was at least correlated with you feeling weak.
But this thing is targeted towards serious endurance athletes, which I am not. I run but am not super serious about it.
Who Actually Makes this Thing?
The branding is a bit confusing. Abbott, a pharmaceutical company makes it. But it is called the Libre Sense biosensor. But then you get a hat with your first subscription that says “Super Sapiens”. So the branding is a little all over the place. I would try and simplify if I were them.
What have I learned health wise?
I wear the Libre Sense more for general health than for competitive endurance athletics. A few years ago I saw that my fasting glucose was 102, which is the prediabetic range. This really woke me up about my health which drives me to want to monitor my blood glucose.
So what have I learned about my health or at least blood glucose? Quite a bit, actually.
First off, I have learned what spikes my blood glucose the most.
What does it? Pretzels and croissants. Basically white bread.
I remember the first time I had a salted, buttered pretzel while wearing the Libre Sense. I used to get one of these I passed by a local train station that has super good ones. My glucose spiked to 175 or so; the highest I had seen it. Also, croissants, which my two year old son loves and are everywhere here in Switzerland, also do it. They’re just 99% white bread. So white bread does it the most.
Surprisingly, ice cream nor pizza massively spike it (meaning the peak number not area under the curve). Why? I think it is the combination of fats and other things mixed together. So when you eat a pretzel or croissant on an empty stomach it is just pure carbs hitting your stomach lining. When you mix those carbs with a bunch of thick fats like melted cheese and the cream in ice cream, those also touch our stomach lining. This appears to slow, but of course not eliminate, the absorption of carbs. So that was a huge learning.
The other takeaway is that my blood glucose seems to just run high, almost no matter what I do (unless I am lying to myself about my diet and amount of exercise). My fasting glucose will just not go under low 90s no matter what I do (the “healthy” range is 70-100, so I am always at the high end of that). It basically will stay at 100 or so, unless I do strenuous weight lifting or take berberine or some other supplement or drug that reduces glucose.
One more learning has been that resistance training seems to have the longest lasting effect on my glucose. It will be a solid 10% lower for at least 24 hours following a strenuous bout of resistance training. And when I do eat, the glucose is slurped up by my muscles or related process. So the steepness of the decline post-prandial is steeper than if I don’t resistance train. Running does not do it for the same length of time (I think also not to the extent but I am not sure about that), though that will reduce it. So that has caused me to tip more towards resistance training than endurance exercise for health purposes.