I had a colonoscopy done a few years ago (thank G for pumps lol as the pump kept me nice and stable bg wise)
I had a mild sedative at the start of the procedure and was ok watching it all on the monitor but towards the end, it got a bit painful so asked to be knocked out and I didnt remember anymore after that.
I came round in the recovery area about 10mins after the procedure had been done and was ok, had a cup of tea and a biscuit and got dressed and went home with my OH. I didn't feel drowsy at all and slept ok at night.
To play safe.......keep bg levels a bit higher overnight by reducing the night basal or by eating some carb before going to bed.
You will also probably need to reduce your daytime basal after a day of sitting on the loo emptying your insides of everything you have eaten.
Good luck......its not that bad really and you may find it interesting to watch it all on the monitor