Moreover, the A1C test can be unreliable for diagnosing or monitoring African Americans with sickle cell trait, sickle cell anemia or thalassemia—conditions that affect the red blood cell. Individuals in these groups have a less common type of hemoglobin known as a hemoglobin variant that can interfere with the A1C test. This interference can result in lower A1C values which can lead to a delay in diagnosis and treatment of diabetes. In fact, a recent study published in the Journal of the American Medical Association showed the diagnosis of prediabetes and diabetes based on A1C results was significantly lower among African Americans with sickle cell trait. When the researchers compared A1C results to fasting glucose or 2-hour glucose results, they found A1C results that were expected to be 6 percent were only 5.7 percent for African Americans with sickle cell trait.
People with sickle cell trait and other hemoglobin variants have no symptoms. If you have any of the following you may be at risk for having a hemoglobin variant:
- you are of African, Mediterranean, or Southeast Asian heritage
- members of your family have sickle cell trait or sickle cell anemia
- the results of your blood glucose test or SMBG don’t match the results of your A1C test
- your A1C result is different than expected
- your A1C result is very high—above 15 percent
- your most recent A1C result is very different from your last A1C result
If you have any of these risk factors, your health care provider can order other blood test to confirm whether you have a hemoglobin variant.
There are special A1C test available that can provide reliable, accurate results for people with a hemoglobin variant. You and your healthcare provider can also use your daily blood glucose readings to show how well controlled your diabetes is.
diagnosis is 5.7 percent to 6.4 percent. You will be diagnosed with diabetes if your A1C is above 6.5 percent. The A1C goal for many people with diabetes is below 7 percent. However, depending on your diabetes history and general health your goal may be different. You should discuss your A1C target with your health care provider.