Whether you have just been diagnosed with diabetes or you've had it for awhile, you've surely heard the term "hemoglobin A1C" tossed around by your doctor. Here are answers to some important questions about this test.

1. What exactly does the hemoglobin A1C measure?
The hemoglobin A1C is a simple blood test that provides an estimate of what your average blood sugar has been for the three previous months, explains Tracy Breen, MD, clinical director of the Mount Sinai Diabetes Center in New York City.

2. Does this test require any preparation?
No, that's what's nice about it. You don't need to eat or drink anything beforehand, but you don't have to avoid eating or drinking either. The results aren't affected by whether a person is fasting or not that day, and a person's blood sugar on the day the blood is drawn won't skew the results either, Breen explains. "This is why it is such a useful monitoring tool," she says. "It's generally very helpful because it gives you an idea of where you are in terms of blood sugar."

3. How does the hemoglobin A1C test work?
Glucose attaches to hemoglobin in your body, explains Shahla Nader, MD, professor of endocrinology at The University of Texas Health Science Center at Houston (UTHealth). "It gives you what we call glycohemoglobin. If your blood sugar has been high, your glycohemoglobin will be elevated."

4. If I get a hemoglobin A1C test, does this mean I don't need to test my blood sugar any longer?
Nope. It gives the big picture, but not the day-to-day details that you need to know to keep you healthy on a daily basis, Breen says. "The hemoglobin A1C can give you an average, but yet you could still have a bunch of highs and a bunch of lows over the course of the three months that aren't showing up," she explains. "You don't want to wait three months to know how you are doing." If your blood sugar is going up and down, the doctor will want to know about this so that medications, diet, and exercise can be adjusted.

5. Can the hemoglobin A1C be used to diagnose diabetes?
Just recently, the test has been approved for use in the diagnosis of diabetes. There are certain criteria that are used to tell if a patient has diabetes or prediabetes. People whose hemoglobin A1C is 6.5 percent or higher have diabetes. Those with a hemoglobin A1C of 6 to 6.5 percent are considered prediabetic, Breen says. "It's important for people in this gray area to recognize that there is some unhealthy process going on in their body that they need to heed," Breen says.

6. Is the result of the hemoglobin A1C only something the doctor needs to know?
Definitely the patient should be aware of her hemoglobin A1C and then work to improve it, Breen says. "Diabetes is a self managed disease," she explains. "Home monitoring of the blood sugar is important, but so is being aware of the hemoglobin A1C." You'll want to have a conversation with the health care provider to find out how to bring the hemoglobin A1C down, if it's elevated.

7. Can any other factors skew the results of the hemoglobin A1C?
Certain blood disorders can affect the test results, Nader says. Sickle cell anemia is one disorder that can skew the results, so make your health care provider aware of any existing conditions you might have.

8. If I am interested in becoming pregnant, should my hemoglobin A1C be below a certain level?
Diabetic women should aim to have a "near normal" hemoglobin A1C before they get pregnant. Non-diabetics typically have a hemoglobin A1C of less than 6 percent and usually this decreases to less than 5 percent during a pregnancy. "When someone has diabetes, we try to get her hemoglobin A1C below 6 percent before conception since we know that high blood sugar is consistent with congenital malformations in the baby," Breen says.