Welcome to the Forum, Steve!
We all could use a manual sometimes, sadly there is not one. If you do need to know something about the app, you can find the answer to most questions in the GB Support Section.
In answer to your T2, read and learn all you can about your condition. Most doctors and endos can't or won't answer most of our questions. There is a lot of good info in the T2 Section. If you have questions just ask, hopefully someone can give you an answer.
Good luck with your control and management!