After noticing Apple Health doesn't let you track this data at all (very strange decision on their part) I contemplated building an app... But Excel is easier and serves the same function. Conditional highlighting, charts, trends, it's all there.
Apple Health tracks the data. It just doesn't provide graphs except for the most common variables. I'm not really sure why no one makes a graphing app that works off HealthKit data
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...