Not a gymnast but a patent of one and I was diagnosed when I was nine. You will need to monitor your glucose closely. If you feel the slightest bit low, it is a NOW thing. Not a one more rep then I'll check thing. You need to have something to treat lows in your bag and a back up set in the gym. You will need to establish safe parameters with your doctor. Something like under 100, no beam for you. Talk to your doctor or nurse educator about a plan for the nights after practice. Often my sugars run lower a few hours after I exercise. Sometimes up to 4-8 hours later.
It is my opinion that the faster you can get a pump the better also for an athlete the dexcom continuous glucose sensor would help too. Both are expensive but worth fighting your insurance for.
Good luck, be patient with the learning curve.