September 12, 2004
A1c (Glycohemoglobin, HgbA1c)
Question from Cleveland, Ohio, USA:
What is the difference between the following tests and their results: glycohemoglobin or glycosolated hemoglobin versus HbgA1c or A1c or hemoglobin A1c or HbA1c?
These terms all measure the same thing – the amount of glucose attached to the hemoglobin part of the red blood cell. The terms are used interchangeably. Throughout its lifetime, the red blood cell allows glucose to attach. The higher the blood sugar, the more of it attaches to the hemoglobin. Since red blood cells live about 120 days, it is wise to check an A1c a about every three months. A1c test results are becoming more standardized across laboratories. That means that, in many laboratories, a 6% A1c equates with an average blood glucose of 135/dl (7.5 mmol/L). For every one point about that, add another 35 mg/dl (or 2 mmol/L) to the blood glucose average. So, a 7% is an average of 170 (9.5 mmol/L), and 8% is an average of 205 (11.5 mmol/L) and so on.