Hi, Asa.
I am also a diabetic. I worried about food and pouch. But I managed to have my lowest glucose readings when I was recovering from surgery 1 and 2. I ate simple carbs to help thicken output. Pasta, rice, and yes, even dense, high glycemic bagels and white toast with protein peanut butter, almond butter, eggs. I drank a Mason jar of broth every day to boost hydration.
The key is portion control, and you already are expert at this as a diabetic! I had one slice of bread or half a bagel with almond butter; one cup rice, pasta, etc., etc., just like the recommendations for diabetics. You can carefully choose simple carbs and soluble fiber for now. I don't know if it was because I was so thin, with very low body fat after my surgery, but my blood sugar was 6 for many months, which is excellent. (Now, not so much!). I ate pasta and rice but always, always together with a protein (fish, chicken, tofu, beef, egg) to slow down the sugar spike. No insoluble fiber during recovery, even though fiber is key to managing diabetes. You won't be able to stand the fiber after your surgery. It will cause your pouch to cramp and roil and be very angry. Explosively angry. I thought that I was fine at the two week point so I ate buckwheat salad with shredded carrots. I thought I was going to pass out from cramps and pain. It's important that your new pouch settle in and learn how to hold and when to release. And you can do this, and manage your diabetes, through portioning and choosing the right kind of carbs at this stage; you can always return to complex carbs when your pouch matures.