Your A1C levels are a commonly used indicator for diabetes control. Hemoglobin is the protein that allows red blood cells to transport oxygen. Glucose reacts with hemoglobin to form A1C; the higher your blood glucose levels, the more hemoglobin A1C you will have. The percentage of your hemoglobin that is in the A1C form is often used to measure your average blood glucose levels. Normally, your A1C level is converted to give an estimate of your average blood glucose level, but you can also convert average blood glucose levels to A1C.
Obtain several blood glucose readings. Your A1C level will reflect your average blood glucose level, so if you want to estimate your percentage of hemoglobin A1C, you need to get a sense of your average blood glucose level. Measure your blood glucose levels several times each day for multiple days. The Family Doctor website recommends talking to your doctor to determine how often you need to measure your blood glucose levels, but you should try to measure the amount of glucose in your blood before and after meals.
Average your blood glucose readings. Because A1C is determined by the amount of glucose in your blood over the span of several weeks, Lab Tests Online explains, you will need to use an average of many readings. Utilizing only one blood glucose reading could cause you to significantly overestimate or underestimate your A1C levels.
Add 46.7 to your average blood glucose level. The formula for converting A1C to an estimated average blood glucose level, reports the American Diabetes Association, is (28.7 x A1C) - 46.7 = estimated Average Glucose. Thus, the first step for performing the reverse calculation is to add 46.7 to your average blood glucose.
Divide the result by 28.7. This will give you a number that represents an estimate of how much of your hemoglobin is in the A1C form. In general, if you have diabetes you should try to keep this number under 7 percent.