do blood glucose levels increase or decrease during fast? (not diabetic)

say i start a water fast, how will by blood Sugar levels be on around the 5 day mark?

is there any chance about a weeklong or a little less of a fast will increase blood Sugar levels.

im asking because i want to start a fast today, but on next thursday i am getting a blood Sugar test done. so will this fasting increase my levels by then.

im not diabetic, i just dont want it to look like i am on the test.