Wondering what can cause rise in blood glucose while intermittent fasting, i had recent lab work that included a1c of 5.5. i have heard the fasting can cause a glucose rise from falling insulin levels and increase urine output (water loss). accurate?

I am not sure where you get all those information but I have never heard off. There is one thing called "dawn phenomenon" when glucose is low enough in a treated diabetic patient triggers a spike in all hormones which have the opposite effect of Insulin and cause a spike on blood glucose so the glycemia is still normal & it could mask the previous episode of low blood sugar. Your HbA1C is good.