The A1c blood test is one of the laboratory tests used to diagnose diabetes and an important measure of average blood sugar levels in someone who has diabetes. This test determines the amount of glucose or sugar that has attached to the blood's hemoglobin -- the oxygen-carrying protein in red blood cells -- during the 3-month lifespan of these cells. Target A1c levels have been established to help healthcare providers, as well as children with diabetes and their families, understand the blood sugar goals needed to reduce the risk of the long-term complications of diabetes. While there are some situations where the A1c result may not be reliable, as a rule this test is accurate and an essential part of a child's diabetes management program.
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Normal A1c Levels
Diagnostic criteria for children is similar to the guidelines used in adults, and the A1c is one of the tests used to diagnose diabetes. A1c levels are reported as a percentage, and often the estimated average glucose (eAG) -- a number calculated from the A1c reading -- is also included with the results. Using the same units as a blood glucose meter, the eAG makes understanding the A1c result a bit easier by comparing the A1c to average blood sugar levels. A normal, nondiabetic A1c level is below 5.7 percent, which reflects an eAG below 117 mg/dL. The level used to diagnose diabetes is 6.5 percent and above, which reflects an eAG of 140 mg/dL or higher. A1c levels above normal but below the diabetes range fit into a prediabetes range.
Target A1c Levels
Along with its role in diagnosing diabetes, the A1c test is performed between 2 and 4 times per year to estimate average blood sugar levels over the previous 3 months. This test is used to monitor the effectiveness of diabetes treatment and to determine if overall blood sugar goals are being met. The American Diabetes Association recommends a target A1c below 7.5 percent in children with diabetes, which is an eAG below 170. This target A1c is higher compared to normal A1c levels, since it's not only challenging for someone with diabetes to consistently achieve normal blood sugars, but aiming for near-normal blood sugar levels when on insulin therapy poses a greater risk of hypoglycemia or low blood sugars. To minimize the risk of severe hypoglycemia, a child's diabetes care team may choose to individualize the A1c target.
When measured by a certified laboratory, the A1c measurement is considered a very accurate reflection of average blood glucose levels over the previous few months. However, there are some circumstances in which the results might not be accurate. Certain genetic variants of hemoglobin such as the sickle cell trait, common in people of African descent, can give unreliable A1c readings. Other genetic variants common in people of Mediterranean or Southeast Asian heritage can also affect A1c results. Any condition that shortens the life span of red blood cells such as hemolytic anemia or recent blood loss could lower A1c levels, while iron-deficiency anemia may increase A1c levels. Inaccurate readings can also occur in people with kidney or liver disease.
Warnings and Precautions
A1c monitoring is an important component of a child’s diabetes management program. However, the A1c value represents an average and does not replace the need for regular blood sugar testing. Glucose meter results help to identify patterns of high and low blood sugars, and the meter data is sometimes more useful when it comes to evaluating the need for therapy changes. In children, the diabetes care team will often individualize the A1c target and may set a higher goal for very young children or in those with frequent hypoglycemia. Or the team may set a more stringent goal if the child can safely achieve this. By working with a diabetes care team to attain target A1c levels, a child can significantly reduce the risk of the long-term health consequences of diabetes.
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- National Glycohemoglobin Standardization Program: Factors That Interfere With HbA1c Test Results
- Merck Manual Professional Version: Diabetes in Children and Adolescents