I’ve been using the Freestyle Libre for over a year now and the third party apps are getting better and better. Glimp has now reached the point where it can post data to Nightscout. And very successful it is too. I’ve got my hands on an Alpha version of the code, and deployed it, and it all seems to work very well.
Now, parents can get teachers to scan using an android phone and see what their kid’s glucose levels are throughout the day. One might argue that this could be considered overprotective on the part of the parents, surveilling their kids 24/7, but that’s not a discussion for this post.
What’s interesting is that Libre data is now transmissible to NightScout and the interesting factors that this chucks up.
So let’s take a quick look at a Nightscout print:
This will be familiar to users of NightScout. A series of dots showing the data points. It’s perhaps less familiar to those using the Libre, and highlights the major difference in operation between the Libre and CGM. If you haven’t scanned for fifteen minutes, the data on Libre is 15 mins apart. On a Dexcom, it’s every 5 mins. Regardless.
If we take a look at my overnight trace, we see many more single dots and then a cluster:
What does this mean?
Well, if we review how the Libre works, it collects data every minute and then effectively conflates it to 15 minute interval data. As a result, you only ever see a point in time reading for every fifteen minutes more than 15 minutes after the last sensor scan. Both of these occurrences can be seen in the picture above. The highlighted cluster is the data between the end of the last 15 minute interval and the sensor scan.
Scanning the Libre effectively resets this interval, as the below picture shows:
The period between 7am and 8am has multiple data points taken at a minute basis as a result of scanning more frequently than every 15 minutes.
But what do these pretty graphs really show us? Well, I guess they show us what we’ve chosen to forget about the Libre. The data, when not scanned, is really only captured every fifteen minutes, and the pretty graphs that the Libre app suite, Liapp, Glimp and the scanner all produce are interpolated from the 15 minute point in time data, helping us to imagine what a 100% trace looks like, but which isn’t really in existence.
Sure, it’s good enough and allows you to manage your diabetes much more effectively, but it is worth remembering how the system works.
And of course, you get all the reports that NightScout provides, which look remarkably similar to those in the Libre package!
Ultimately, it’s a step in the right direction, and it’s what I was asking for in the midst of Diabetes Awareness Month. It is something that could be easily usable by a clinic to keep an eye on what a patient was doing, if they so wanted. Well done to the team at Glimp for getting this into the platform and working. The next question is whether the LibreLink app will be even half as capable? Guess where my money is going…