Historically, tests for diabetes measure the amount of sugar in the blood. But these tests offer only a snapshot of blood glucose levels at the moment the bood is drawn, not broader information about longer-term blood sugar control. Today, a new test is becoming the standard for blood sugar measurement and control: the A1c test.
What is A1c?
The A1c test measures the HgbA1c level in the blood. What is HgbA1c? Let’s break it down:
Hgb stands for hemoglobin, the component of red blood cells that ferries oxygen from the lungs to the rest of the cells in the body.
A stands for Adult, but don’t be thrown off by that. With hemoglobin, an adult is anyone over the age of six months. There are other types of hemoglobin in the blood, but in anyone older than six months, virtually all of it is Type A.
1 refers to the type of HgbA in the blood. There are several types of HgbA in the blood, but 98% of it is Type 1.
c is a subtype of HgbA1. Here, finally, blood sugar enters the picture. Glucose attaches itself to hemoglobin, but mostly to just one type of hemoglobin. Glucose-attached hemoglobin, “glycated” hemoglobin in medical parlance, is usually subtype c. In fact, two-thirds of a person’s glycated hemoglobin is HgbA1c, making this particular subtype of hemoglobin the best marker for blood glucose levels.
The more HgbA1c in the blood, the more sugar in the blood.
Advantages of the A1c test
The A1c test:
- Reports how well blood sugar has been controlled over the last three months, not just at the moment of the test.
- Does not require fasting, so it can be given at any time.
- Is not as likely as a fasting glucose test to be affected by stress or other illness.
- Reveals prediabetes, not just diabetes, which makes it an especially useful diagnostic tool.
Like other glucose tests, home kits are available for the A1c test.
A1c Test Results
An A1c level below 5.7% is normal.
An A1c level between 5.7% and 6.4% indicates prediabetes.
An A1c level above 6.5% indicates high blood sugar.
An A1c level above 6.5% on two separate tests is diagnostic of diabetes.
Like most tests, the A1c is not foolproof. A variety of conditions, including excessive alcohol intake or anemia, can yield inaccurate results. Moreover, there are times when a diabetic needs to see a snapshot of their blood glucose level, and not just a three-month average.
Nevertheless, for long-term blood sugar management, the A1c has become an invaluable tool in the diabetic toolkit.