GD question for people that have it.

Bree • I`m 27 yrs old and have one son (8). I just had our second. Not sure if we're done or not.
I'm wanting to know what numbers you need to stay between to have normal-good blood sugars. I tested mine tonight and it was 81. I had gestational diabetes the last time I was pregnant (8+yrs) And the doctor is pretty certain it's back. What's the number range for normal low and high?