The A1C test (also known as the hemoglobin A1C or HbA1C test) provides a long-term gauge of blood sugar control. It can show you how well you've been managing your diabetes over the past few months. As a result, A1C can be an excellent tool for helping identify a person's risk of long-term complications, looking at the big picture, and assessing a woman's readiness to start a family.
The A1C test is not, however, a substitute for frequent self-monitoring. Instead, it complements the tests you perform yourself. It's still necessary to know how meals, activity, medications and stress affect your blood sugar on a daily and weekly basis. The A1C won't show that. In fact, frequent highs and lows can average out to a healthy-looking A1C result—you need your self-testing results to fill in the details.
The American Diabetes Associations recommends an A1C test every three months. For people who are under good control and are not changing their therapy, an A1C test every six months may be acceptable.1 Your doctor will help you decide what's right for you.
Your A1C test measures your average blood sugar levels over a three-month period by taking a sample of hemoglobin A1C molecules—a specific component of your red blood cells.
Some blood sugar (or glucose) naturally attaches itself to these A1C molecules as they move through your bloodstream. When this happens, the molecule is considered "glycated." The more sugar in your blood, the higher the percentage of glycated A1C molecules you'll have.
Once a cell has been glycated, it stays that way. And since each A1C molecule has a lifespan of about four months, your A1C sample will include cells that are a few days, a few weeks and a few months old. That's how the test result covers a span of about three months.
Of course, without regular self-testing to provide day-to-day insights, an A1C result can be misleading. Because it gives a long-term view, a person with frequent highs and lows could have an average A1C that looks quite healthy. The only way to get a complete picture of your blood sugar control is by reviewing your daily log along with your regular A1C tests, and working closely with your healthcare team to interpret the results.
