I had orthoscopic knee surgery last week for a big tear in my miniscus. Discussed what we needed to do with my D with the anesthesiologist- he is the one in charge of the patient while we're "out". The plan was to not eat, and for me to be at least 100 for the surgery. So the day was a big basal test for a surgery at 1:45PM.
The day went smashingly well. I was 95-110 all day. I was hungry, but was on track UNTIL I GOT TO SURGERY. I knew I was a little stressed, but then the surgery time was moved up. I got rushed down the hall to get ready. Then my BS dropped to 58. CRAP!
Since I couldn't eat, 5% dextrose drip was the fix. This made me mad, but after the surgery I was 192. And I knew I could fix it. With my pump still on, I started working on it as-soon-as I was awake.
You need to talk through your plan and comfort level with your anesthesiologist.