The hemoglobin A1C test is the gold standard for measuring your overall glucose control. The A1C is drawn from your arm and measures your average glucose for the previous three months. You do not need to be fasting. The higher the A1C reading, the higher your glucose levels have been during that period.
The A1C goal for most people with diabetes is 6.5% or below. If you have existing heart disease or other serious medical conditions your physician may recommend 7 percent or below.
A1C tells the real story. When you use your home meter to test your glucose, it is a snapshot of your glucose level at that moment. If your testing regimen is four times a day, three days a week, these snapshots tell what your glucose levels have been for 12 seconds out of a whole week. Your A1C tells you how your glucose was doing for every second of every day for the previous three months.
How does it work? Our blood vessels contain millions of red blood cells that circulate throughout our body delivering and releasing oxygen molecules to our tissues. The hemoglobin (protein) in these cells also picks up glucose molecules. Once a glucose molecule attaches to the cell it stays attached for the life of the cell, about three months. The A1C test measures how many glucose molecules are attached to the cells. Higher glucose levels over a three month period will cause more glucose molecules to stick to the cells and a higher A1C result.