I once went down the rabbit hole of trying to determine what exactly the definition of a hypo is.
This site says
Wikipedia says
https://www.diabetes.org.uk/guide-to-diabetes/complications/hypos says
The
U.S. Department of Health and Human Services (An official website of the United States government) say :
But apparently the Europeans
don't agree with that definition because the
document that they link to actually says
(emphasis is mine)
The freestyle app seems to use below 3.9
from
https://www.freestylelibre.co.uk/libre/discover/using-your-meter.html
And just when you think you can conclude that it is either below 4.0 or below 3.9, and that there wasn't really much difference, then along comes our very own
NHS !