HbA1c Test Important for Diabetes

The hemoglobin A1c test, also called HbA1c, glycated hemoglobin test, or glycohemoglobin, is an important blood test that shows how well your diabetes is being managed, or not being managed. Hemoglobin A1c provides an average of your blood glucose management over the past 4 months and is used along with home blood glucose monitoring to make adjustments in your diabetes medicines.

The past four months means the prior 120 days. Fifty percent of the prior 30 days is used for the A1c. Day 31 to 60 accounts for 25 percent and day 61 to 120 accounts for the remaining 25 percent of the A1c.

The A1c is important; however, many doctors only use the A1c and do not look at the records he asked you to keep. Some doctors even go one step further and do not suggest daily blood glucose testing. They follow the advice of Dr. Robert Ratner, chief scientific and medical officer of the American Diabetes Association, who says, “Many people with type 2 diabetes who are on medications don't need to do home glucose monitoring at all," in talking about oral medications.

Hemoglobin is found in red blood cells, which carry oxygen throughout your body. When your diabetes is not managed (meaning that your blood glucose level is too high), glucose builds up in your blood and combines with your hemoglobin, becoming "glycated." The average amount of glucose in your blood can be found by measuring your hemoglobin A1c level. If your glucose levels have been high over recent weeks, your hemoglobin A1c test will be higher.

For people without diabetes, the normal range for the hemoglobin A1c test is between 4% and 5.6%. Hemoglobin A1c levels between 5.7% and 6.4% indicate increased risk of diabetes (pre-diabetes range), and levels of 6.5% or higher indicate diabetes.

Because studies have repeatedly shown that poor diabetes management results in complications from the disease, the goal for people with diabetes is a hemoglobin A1c less than 6.5% (equals 140 mg/dl). The higher the hemoglobin A1c, the higher the risks of developing complications related to diabetes.

People with diabetes should have this test every 3 months to determine whether their blood sugars have reached the target level of control. Those who have their diabetes under good control may be able to wait longer between the blood tests, but experts recommend checking at least 2 times a year.

People with diseases affecting hemoglobin, such as anemia, may get abnormal results with this test. Other abnormalities that can affect the results of the hemoglobin A1c include supplements such as vitamins C and E and high cholesterol levels. Kidney disease and liver disease may also affect the result of the hemoglobin A1c test. A blood transfusion can also cause an unreliable A1c.