Um, yeah, please don't do this to your daughter!

Is she already seeing a therapist for her bipolar? I'm sure it's hard to see her gaining weight and dealing with diabetes - but I'm equally sure that she's AWARE of the problem, and would probably like to change it. Calling her out on it is just likely to humiliate her, and make her want to eat more for comfort.

(That's what it would do to me, and I've struggled with weight my whole life.)

We all have a limited amount of energy to spend "fixing ourselves". If she's already dealing with therapy, she may have plenty to work on without also tackling the weight/health issues. It sucks, but that's life. We can't do everything at once.

The best thing you can do, in my opinion, is support her, love her, and accept her as she is... let her know she's a human with more to offer than just her looks. Good luck!