there are some circumstances that can affect the accuracy of an A1C result. If you have recently had a blood transfusion, suffered significant blood loss, or you suffer from some forms of anemia you should discuss your condition with your health care provider.
WHAT IS NORMAL?
Depending on the laboratory your physician uses, the normal range of an A1C level is about 4–6%. Check with your physician about what reference range is used, as it is normal to see some variation between laboratory reports, depending on how the analysis is performed. A 4–6% A1C level compares to an average blood glucose level of approximately 70–120 mg/dl, which is considered to be “normal.”
The American Diabetes Association recommends people with diabetes keep their A1C levels below 7% (lower for some), which is a glucose reading of approximately 150 mg/dl on average over a 2–3 month period. (The American Association of Clinical Endocri-nologists supports a slightly lower goal of less than 6.5%, equal to about 140 mg/dl over the same period of time.) Discuss your own target with your health care team. There may be times when your target might need to change (during pregnancy, when treated for other health problems, etc.).
THE WORD “AVERAGE” IS KEY
While an A1C check provides great information, it is not a replacement for daily blood glucose testing. Your daily tests should be reviewed alongside an A1C test to help you understand your daily and overall control. Because A1C is an average, it will not show if you are having problems with hypoglycemia or experiencing unstable readings. It is an important test, but trends in your daily blood glucose cannot be identifed by A1C results alone.
WHERE DO YOU HAVE AN A1C CHECK DONE?
A1C checks are usually done at your doctor’s office, either with equipment on the premises or through a blood sample that is drawn and sent to a laboratory. The result will be sent to the office in a few days to a week. Make sure you get the result and discuss it with your health care providers.
HOW OFTEN SHOULD AN A1C CHECK BE DONE?
The American Diabetes Association currently recommends you have an A1C done twice a year if you are meeting treatment goals and quarterly (every 3 months) if your therapy has changed, or you’re not meeting treatment goals. An A1C will not generally be repeated any sooner than 2 months from the last check unless special circumstances warrant it.
ESTIMATED AVERAGE GLUCOSE
The term estimated average glucose, or eAG for short, is a new way of showing average blood glucose information in the same units (mg/dl) that people are used to seeing on their meters and glucose lab reports, rather than using a percentage like A1C. A1C percentage is sometimes confusing to people, so having your results in terms of a meter value may make the information more realistic and intriguing. Still, it’s simply a different way of showing the same thing—your average glucose over a period of months.
IS YOUR A1C THE SAME AS YOUR eAG?
Not exactly, but it is another way to interpret your control. The eAG will soon be the standard reporting value for health care providers and patients, so you should know how the two values relate to one another. The following is a chart that shows how the two results compare:
IS THE “AVERAGE” REPORTED ON YOUR BLOOD GLUCOSE METER THE SAME AS eAG?
No. The “average” on your meter only reflects the average from the readings you performed. If you only check a few times a day like most people, you only have a few points of data, and not the constant data that’s represented by an eAG or A1C check. The eAG reflects what your blood glucose readings were 24/7 for 3 months.
ONCE YOU HAVE YOUR RESULT
YOUR A1C IS HIGHER THAN 7%. WHAT NOW?
If your test result is higher than your target, immediately discuss with your health care providers what you can do to improve your results in the future. Don’t wait until the next visit! Consider your management plan and ask yourself:
HOW DO YOU CALCULATE YOUR eAG?
You can calculate your eAG using your current A1C result. The formula is as follows:
(28.7 x A1C) — 46.7 = eAG
It’s probably been a while since math class, so an example to illustrate may make it more clear. Let’s say your A1C is 8.2%. For the formula, you treat your A1C result simply as a number and not a percentage. So to calculate your eAG, you would first multiply 28.7 by 8.2 (your A1C):
28.7 x 8.2 = 235.34
Now, you would take this number, 235.34, and subtract 46.7:
235.34–46.7 = 188.64
Then just round up to the nearest whole number, 189, and you have your eAG. In this case, that would be an average blood glucose of 189 mg/dl over a 3-month period. Seeing this should illustrate how eAG is useful. If your doctor says you have an A1C of 8.2%, you probably realize that is high, but it can also be just another number. However, if your doctor says your blood glucose level averages 189 mg/dl, you have a much more concrete idea of what that means. Mostly, it means you’ve got some work to do!
Learn what options your health care providers have to suggest. A high A1C is not simply your fault; it is a problem to be dealt with by you and your health care team.
WHAT IF YOUR SELF GLUCOSE CHECKS DON’T MATCH YOUR A1C?
It is possible your blood glucose meter may need to be replaced, or you’re not following the manufacturer’s guidelines. However, it’s more likely that the variation comes from the different nature of each test. An A1C only reports an average—it cannot show daily fluctuations. Conversely, you may need to do your self glucose checks at different times of the day. Always checking at the same times of day will limit your ability to fully understand your glucose levels over a 24-hour period.
Remember, an A1C result of 7% compares to a blood glucose average of about 150 mg/dl. Think of how many different ways you can mathematically achieve this average, even with just two blood glucose numbers obtained each day during a month. Consider the individuals below:
All four of these individuals
