The gym helps, but research shows that to lose weight on exercise alone, you need to do a LOT of it.
Weight problems often come to T1s who are using too much insulin{like my T1 husband was)
Reducing your carbs and reducing your insulin in line with that SHOULD help. It should also help with hypos and highs.
The defining book is Dr. Bernstein's Diabetes Solution. Ask your library for it. They often don't have it and will order it in. the book explains everything
Hana