The A1C Test: How It Helps Manage and Treat Diabetes

See why the A1C test is crucial for better diabetes control.

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If you have diabetes, checking your blood sugar at home may be as much a part of your daily routine as brushing your teeth or checking the weather forecast. Because the A1C test is not part of your daily habits, you may be less familiar with your number, or why it matters. But understanding the value of the A1C test (and aiming for a healthy number) is critical for optimal diabetes control.

How Does the A1C Test for Diabetes Work?

The A1C for diabetes is a blood test that reveals your average blood sugar levels over the past three months. While it can be used to diagnose diabetes, it’s also used to assess a person’s health and diabetes control as they live with the disease over time. It’s recommended that all diabetes patients get their A1C tested at least twice a year. Here’s more info about getting the right medical care with type 2 diabetes.

The A1C test is based on the attachment of blood sugar, or glucose, to hemoglobin, a protein in red blood cells that carries oxygen. Red blood cells are constantly forming and dying, but in general, they live in the body for about three months. The A1C test result is reported as a percentage; the higher the percentage, the higher a person’s blood sugar levels have been during those past three months.

The reason doctors want to see an average blood sugar reading is because single, real-time measurements aren’t indicative of the big picture, and they’re very easily influenced by your diet, stress levels, or other factors. If you checked your blood sugar right now, then checked it four hours later, it might be completely different, says Sandra Arévalo, RDN, CDE, a spokesperson for the American Association of Diabetes Educators. Just checking your blood sugar at that moment isn’t a good indicator of whether or not your diabetes is well managed. “So A1C gives us that opportunity to diagnose and know how well controlled [your diabetes] is,” says Arévalo.

What’s an Ideal A1C for People with Diabetes?

An ideal A1C is different for everyone, but in general people with diabetes should aim for less than 7%, says Minisha Sood, MD, an endocrinologist in New York City. “But that may be an individualized goal depending on someone’s age,  or other medical problems that they might have.” Patients with other medical complications might be better off with a slightly higher A1C, for example. Talk to your doctor to find out what your specific A1C goal should be.

What Happens If Your A1C Is Too High?

A higher hemoglobin A1C can increase your risk of diabetes complications or worsen existing complications. “If I have a patient and I see that their hemoglobin A1C is rising, it’s an opportunity to discuss with them what’s happening on their end,”  says Paul Knoepflmacher, MD, a clinical instructor in medicine at Mount Sinai Hospital in New York City. “Have they changed their diet? Are they exercising less? Are they gaining weight? And on my end it’s an opportunity to think about what medicines there are, and do I need to alter them or adjust them to better control their blood sugar.”