[bigiain]

<cynical view> Because that's totally a thing Apple will release (or bundle into an existing app) as soon as it gains any popularity...

<sightly less cynical view> There's been persistent rumours for a few years now that Apple are working on blood glucose sensing for Apple Watch. If those rumours are right (and a big part of me really hopes they are) then that'd likely come with built in apps that destroy every blood glucose related 3rd party app.

Edit: I just noticed the original post wasn't specifically blood _glucose_ related. My own "blood test" requirements made me jump to an erroneous conclusion...