The A1c test measures how much glucose is stuck to your hemoglobin, or more specifically, what percent of hemoglobin proteins are attached to glucose. So if you have a 7% A1c, that means that 7% of your hemoglobin proteins are glycated.
Once glucose sticks to a hemoglobin protein, it stays there for the lifespan of the hemoglobin protein, or for about 120 days. That's why, at any moment, the glucose attached to your hemoglobin A protein reflects the level of your blood sugar over two to three months.
For a person without diabetes, a typical A1c level is about 5%. If you have diabetes, it's recommended, by the American Association of Clinical Endocrinologists (AACE), that a level of 6.5% or below should be your target goal. The American Diabetes Association (ADA) suggests a goal of 7% or lower.