I've had surgery 3 times since my T2 diagnosis. The first time due to inaccurate fasting advice and an unforeseen delay on the day, I went 17 hours without food and was beside myself with "false hypo" symptoms - my BG was about 3.5 IIRC, which felt like a lot lower to someone not used to that. So they corrected it with some glucose in theatre, which sent me up to about 17. Not cool.
The other two times, the fast was shorter but I still went low and they corrected this slowly with a bag of saline that had a little glucose in it, by IV over about 4 hours, while I waited for the op. This was much better and my BG after the op was only 9 or something. Also, they tested my BG every hour while I was on the IV glucose. I think that would be really important for a T1.
My advice (from a T2 perspective, so it might not apply to T1) is to stay up as late as possible the night before so you can make your fast as short as possible. If you need glucose at the hospital, a slow drip is probably better than a shot of glucose in one go. Make sure the procedure is going to happen at 9am - either it's an appointment time, or you are first on the surgical list. Diabetics should always be first on the list if possible. If the procedure is going to happen at 11 am, then ideally you would eat at 4am, which is pretty inconvenient. If I have the chance to, I try to get procedures scheduled for the afternoon, so I can have a small breakfast.
Good luck!