How does hba1c actually work?

Complicated..: Tells your average blood glucose level over 3 months period, actual biochemical mechanism is complicated..

Hemoglobin A1C: This is the best screening test for a pre-diabetic or diabetic situation. This test can guestimate the overall level of your blood sugars over a ninety day period (the natural life of red blood cells). It measures the amount of sugar attached to your red blood cells. If you blood sugar is too high over a prolonged period the red cells will have more sugar on them.

Estimates average gl: The hba1c is an estimate of your average glucose over the past 3 mod, but weighted heavily toward to most recent time period. It measures how much glucose has bound to the hemoglobin molecules in your red blood cells. It is only an estimate, however. It is affected more by postmeal glucose at normal glucose levels, and fasting at higher levels. Doesn't replace glucose monitoring at home.