I am now a week and a half into my one month trial with the soon-to-be-released (in Europe) Abbott flash glucose monitor, the Freestyle Libre. By now there are several places on the Internet to get info about what this new diabetes monitoring device is and how it works. For starters, you can go HERE (I hope that webiste works outside of europe). There are also a number of other bloggers who are trying out the system and since YDMV (your diabetes may vary) I would suggest reading many posts about different experiences with the Libre to get a better idea as to whether it would be a good option for yourself. Check out user reviews by Laura, Mike, Jen and Dave.

One of the most important factors that is influencing my own opinion of the Libre is that I have been using a dexcom CGM for the past year. Flash glucose monitoring is not the same as a “traditional” CGM and it definitely has some advantages and some drawbacks.

This is the first of several posts about this device and I’m going to break them up into individual features that I find are worth considering and give my take on the pros and cons of the Libre. FYI and as illustrated by the fact that I still use an insulin pump that has been off the market for 5 years, I’m quite picky about the features in my diabetes devices. So here goes… Some of my thoughts after 9 days using the freestyle Libre:

Sensor
It is very easy and virtually pain free to insert. The insertor is spring loaded and the action of pressing it onto the arm releases the spring. You feel the pressure of the device on your skin more then the insetor needle going in. It’s easy to do one handed and on either arm no matter if you are using your dominant hand or not.

The sensor itself is smaller than other cgm sensors I have seen. It’s quite low profile (5mm thick) and round so doesn’t get caught on clothing or purse or backpack straps. It’s definitely nicer looking than the dexcom 4G sensor and transmitter. That said, an important difference between the two is that the Libre doesn’t automatically transmit any data. I’ll get back to that in another post.

Duration 
The sensor is meant to last upto 14 days. That’s twice as long as the longest CGM sensor on the market! And of course this could be interesting in terms of cost (I’ll get back to that too!). The meter has a countdown on the home screen to let you know how many days are left. The tape around the sensor is impressively small and I asked the reps at Abbott if it would actually stay stuck for 2 weeks without the need for extra tape. They assured me that it was very sticky and I might even have some difficulty peeling it off at the end of the 14 days.

Unfortunately that didn’t turn out to be true for me. After 6 days, I noticed that the edge of the tape seemed to be peeling up. I had heard of “liquid tape” being spoken about on the diabetes online community and enquired in a pharmacy where they didn’t seem to be aware that anything of the sort existed. I hesitated to buy tape to cover the whole sensor and wasn’t sure enough in my abilities to cut a hole in the tape to the exact dimension of the sensor to be able to overlap the tiny bit of tape already there.

Between a busy work and home life, I didn’t take the time to explore more options for glueing or taping the sensor back down quickly enough and on Saturday morning, 7 1/2 days after putting it in, the sensor simply fell off. I’m pretty sure my dexcom sensor would do the same after 7 days if I didn’t reinforce the tape by the end of the first week. It is only with careful taping and retaping that I am able to get multiple weeks out of a dexcom sensor. But a dex sensor is only supposed to last a week. Libre should be able to last 2.

Reading/scanning 
It’s very easy to obtain a reading from the sensor. Simply press the (one and only) button on the meter and bring it close to the sensor on the back of the arm. The reading, the trend arrow and the graph from the last 8 hours appear instantly. You can also chose to have it beep, vibrate or do nothing at all when you scan the sensor with the meter. It can read through clothing so is convenient in almost any situation. I’m curious about the cold weather though. I noted last winter while on vacation in Canada that my dexcom had a little trouble with the very cold temps. And if using the Libre, you’d have to take it out into the cold to scan through a jacket.

Accuracy
As noted by Abbott, the first 24 hours with a new sensor is indeed its “least accurate period”. I was all set to do my first scan at the end of the one hour startup period. Much to my surprise, the meter read LO (meaning under 40mg/dl or 2.2 mmol/L).  Not having any symptoms of a low, I tested with a finger stick using my regular glucose meter. The 87 (4.8mmol/L) staring back at me made much more sense. But another hour later, all 3 of my devices were in very reasonable agreement:

Since then, I can find no fault in the accuracy compared to dexcom or my meter (especially given the liberal definition of accuracy allowed on glucose meters).  I asked Abbott about dosing insulin off a scanned Libre reading. They gave a vague “talk to your medical professional about it” type of response. But in all honesty, my hcp won’t know this tecnology well enough to give an informed opinion on it and will of course say “only dose insulin for a meal or a correction bolus off a finger stick reading”.

Plus, for anyone who would like to use the bolus calculator included in the meter (I don’t bother as I have that feature in my insulin pump), it can only be used within 15 minutes of a finger stick test using the Libre meter.

Abbott has put a good deal of marketing into the fact that this new flash glucose monitoring technology eliminates the need to stick your fingers (allowing you to enjoy all sorts of gentler sensations with your fingertips… Yadda yadda yadda). But in reality there is still some need for testing, even if you aren’t calibrating the sensor twice daily like with some CGMs.

What the Libre does permit though, is checking glucose levels multiple times per day while only doing a few finger sticks. So far I’ve averaged 16 scans per day which seems like a lot (obsess much?) but also has to do with the fact that I’m testing out the device and comparing it to my meter and my dexcom.

In the next post I’ll get into some of the features of the meter and the data & analysis available both on the meter itself and in the downloadable software.