Summer Workout Goals

I am a T1D and I plan to work out a lot this summer, I was wondering if anyone has any tips that could help.

I figure I have to start eating more than ~40 carbs a day if I want to start gaining muscle. Should I focus more protein or just eating more in general? Are there lower carb protein shakes I should be aware of?

Any non diabetes related tips? Good workout routines? Is cardio good if I want to build muscle, I hear a lot of mixed opinnions. As a shut in university student, this is all a bit new to me. I just want to get rid of these twig arms.

Any help would be appreciated <3