December 7, 2003
A1c (Glycohemoglobin, HgbA1c)
Question from Greensboro, North Carolina, USA:
I am a clinical nurse specialist for the MCHS in Greensboro, North Carolina. My diabetes coordinator team of diabetes nurse specialists are presenting a “Grand Rounds” conference for the entire hospital staff. We are presenting a case study, using one of our main teaching points, the HgbA1C. We have the chart that converts the A1C to the correlating cbg reading, but we would like to know the formula that calculates the conversion. Could you refer me to the appropriate source if you do not have it?
One conversion factor is:
Blood Sugar in mg/dl = 30(A1c – 6) + 120
or if you want to put it the other way round
A1c = ((Blood sugar in mg/dl – 120)/30) + 6
Remember though that there is no expression of variance so that in theory you can have a normal A1c from a mixture of blood sugars that are too high and too low.