What's an A1c test and why is it important for my dad to take it?

A fellow caregiver asked...

My father has recently been diagnosed with type 2 diabetes and I'm coming up to speed on all the medical checks he needs. What's an A1c test and why should he have it?

Expert Answer

Theresa Garnero is clinical nurse manager of Diabetes Services at California Pacific Medical Center in San Francisco.

The A1c test (you pronounce each letter and number separately), also referred to as the hemoglobin A1c or glycosylated hemoglobin test, gives information about your dad's average blood glucose levels over the previous six to eight weeks. It measures the amount of glucose, or sugar, that sticks to the oxygen-carrying protein molecules in red blood cells known as hemoglobin.

Although routine blood glucose testing does a great job of letting your dad know how his blood sugar levels are doing at any given time on any given day, it doesn't provide the big picture. That's the A1c test's job. It gives you and your parent an overview of how well he's keeping his blood sugar in his target range on a regular basis. So it's a handy way to look back over time to see the effects of treatment, such as medication, diet, or exercise changes.

The test itself is simple: A blood sample is taken from your father's finger or arm and then analyzed in a lab or at the clinic. You can also buy a home A1c testing kit at some pharmacies or online by searching for A1c. Check first, though, with your dad's healthcare provider to see whether home testing is appropriate in his case.

The results of the test are given as a percentage; the closer your dad's result is to 7 percent or lower, the nearer he is to everyday blood sugar results in the healthy 75 to 130 milligrams per deciliter range. That's important information to have because every 1 percent jump in your parent's A1c increases his risk of long-term complications, such as kidney damage or vision loss, by 30 percent. Although a score of 7 or under isn't a guarantee your dad will keep complications at bay, it's crucial for him to know his A1c number and take steps to keep it at or below 7 percent to reduce his risk for chronic diabetes-related problems.

The American Diabetes Association recommends that people with type 2 diabetes have an A1c test every three months. Your father's healthcare provider may advise more frequent testing in certain situations, such as when there's a change in medication. A poor result on an A1c gives prompt feedback that tighter control of your dad's blood sugar may be needed. Good results can be very motivating, so if your dad improves his score to 7 percent or less, applaud his efforts and encourage him to keep up the hard work with any self-care changes he may have made.