What does Hgb AC mean?

Hgb = hemoglobin

which is a protein in red blood cells that carries oxygen. blood tests are able to detect how much of this you have in your blood.

I don't know about the AC part, but I'm a type 1 diabetic and I get my Hgb A1c checked every 3 months. And that's a blood test to see how much sugar you have in your blood, pretty much.