As with any Excellent exercise Regimen, fencing will indeed bring your B/G levels down---which means, unfortunately, you'll prbably have to force yourself to eat more
The up side is, while you are eating more, you will be creating muscle mass which causes you to more efficiently metabolize your insulin.
Let's review all the advantages to excellent workout Regemine, shall we:
1. Get to Eat more
2. Use insulin better
3. Live longer
4. Live better
I'd say you should go for it.