What is hemoglobin a1c?

Average blood sugar. Hemoglobin A1c is a measure of the percentage of red blood cells permanently bound to glucose. Normally about 5% of our red cells are glycosolated. If you have greater than 6.5% you are diabetic. It is not affected by fasting, and since our rbc's live 90-120 days, it reflects an average over that time.
Diabetic measure. The HgbA1C is a measure reflective of your degree of diabetic control in the long term. It essentially represents a three month average of your fingersticks, as if you took a fingerstick every minute, night and day, eating and fasting, for three months straight and then averaged them all. Technically, it's the percentage of red blood cells that have glucose attached to them.
A blood sugar test. The hemoglobin a1c test is a blood test used to diagnose type 1 and type 2 diabetes and then to gauge how well you're managing your diabetes. It goes by many other names, including glycated hemoglobin, glycosylated hemoglobin, hemoglobin a1c and hba1c. The a1c test result reflects your average blood sugar level for the past two to three months.