I'd be extreemly careful about using a cell phone app to track any health data at all. The Glucomate app seems to have a pretty reasonable privacy policy at first glance, but I have no idea what kind of app the The Libre uses or what their policy is, but in any case it's worth pointing out that there are countless companies who would love to get their hands on this type of data some of which could impact your ability to get insurance or the rates you'll pay for it. Even advertisers would love to take advantage of you while your levels are (or are expected to be) low and your defenses are down.
If insurance companies are setting premiums based on personally collected data from random apps, the thing to do isn't to advise people to avoid them, the thing to do is to figure out how to feed the random apps data that looks healthy.
Of course health insurance isn't allowed to consider such data, and it's unlikely to be of much value to life insurance (because it has no provenance).
For a very long time insurance companies have been using information collected from data brokers and who knows where that data comes from. I'm guessing they'll use any data they can get their hands on that might in any way help them justify taking more of your money while ignoring or downplaying the rest, but gaming your data wouldn't be a terrible idea if you can pull it off.
> Insurers contend that they use the information to spot health issues in their clients — and flag them so they get services they need. And companies like LexisNexis say the data shouldn't be used to set prices. But as a research scientist from one company told me: "I can't say it hasn't happened." (https://www.propublica.org/article/health-insurers-are-vacuu...)
There now seems to exist an app that can read Libre 3 and feed to Xdrip, APS. I want to try it soon. Unfortunately you still need the official spy app to initialize the sensor.
for libre 2 if you use the bluetooth mode. You actually would install the libre app for initialization and then deinstall it so that it doesn't interfere.