What It Is and Why Bother: The A1C Test
The A1C test is a generally accepted way of diagnosing type 1 and 2 diabetes, and it gives doctors an idea how well a patient’s diabetes treatment plan is working.
A1C (or HbA1c) is formed when sugar attaches to hemoglobin, a protein in our red blood cells. When blood sugar levels are high more sugar sticks to the hemoglobin, so A1C levels go up. Lower blood glucose results in less A1C, since less sugar is coating the hemoglobin.
An A1C test measures our average blood sugar level over the previous two to three months by indicating what percentage of our hemoglobin is coated, or glycated, with sugar. (Three months is the average lifespan of a red blood cell.)
Anything that effects our red blood cell count can alter A1C numbers including blood loss from major surgery, receiving a blood transfusion, having anemia, or other medical conditions. Different ethnic populations may have different levels as well, particularly those with an uncommon hemoglobin variant called hemoglobin A.
To run the A1C test, a patient’s blood is drawn by inserting a needle into an arm vein, or by pricking their finger tip with a lancet. The blood can be taken at any time of day—no fasting required.
It’s best to have the A1C test done just prior to a diabetes checkup, so physician and patient can review the results together. Doctors will suggest when patients should be tested again, and what their recommended A1C target number is.
Your Individualized A1C Test
Many individuals with type 1 or 2 diabetes have an A1C test every three or four months. For adults with type 2 who have been meeting their targets, and have their diabetes is under control, every six months may be adequate. Those with pre-diabetes generally have their A1C checked annually.
A patient’s health care team looks at several factors to decide what A1C targets should be. For most individuals, the target is seven percent or less. People at higher risk of diabetes complications typically have lower target numbers. Those with a history of heart disease, or other chronic illness, may have a target closer to eight percent.
For comparison, non-diabetics’ A1C levels are below 5.7 percent. A result between 5.7 and 6.4 is considered pre-diabetic.
A1C and Monitoring: Dynamic Duo
Even with regular A1C testing, doctors recommend daily glucose monitoring for many type 2 diabetes patients. Though monitoring and A1C each measure blood glucose, they serve different purposes:
- Daily monitoring reveals what a person’s blood sugar is at the time it's measured. By identifying a day’s highs and lows, the best course of action with regards to food, medication, and activity can be determined.
- An A1C value does not fluctuate day to day. It provides a two to three-month blood glucose average that suggests to doctors a patient’s risk for diabetes complications, and indicates how well the current diabetes management plan (e.g., diet, medication, activity) is working.
Regular monitoring and A1C tests are a given for those with type 1 diabetes. For individuals whose type 2 diabetes does not need close monitoring, regular A1C testing may be enough to keep tabs on the illness. Others with type 2 benefit from a diabetes picture created by juxtaposing their daily monitoring and A1C numbers.