It also says I've been below target 15% of the time, that is between 4 and 5.1, always at night. What does concern me a bit is that almost every morning at about 6am (when I'm asleep) I'm below 4 for a few minutes. And on one occasion for more than 15 minutes, triggering a low-glucose warning. Since I'm asleep I can't get any specific readings but on an enlarged picture of the computer graph it looks like high 3s.
This is sort of off topic but the thread has opened out a bit.