What is the HBA1C test?

By | 3 June 2021

The HbA1C test is a blood test that is frequently used in screenings for diabetes patients’ controls and blood sugar levels. Unlike finger glucometers or blood glucose tests, which provide information about instant blood sugar, it forms an important part of the treatment and follow-up process, especially in diabetes patients, as it provides information about the average blood sugar for a certain historical process. This test, which is done by measuring the glycosylated hemoglobin in the blood, which is an answer to the question of what is HbA1C, provides benefits in many areas such as investigating the risks of complications related to high blood sugar in diabetes patients and adjusting the insulin dose in insulin-dependent diabetes patients.

What is the HbA1C test?

HbA1C is a glycosylated hemoglobin test that allows reaching the 2-3 month average level of blood glucose level. A high level of glycosylated hemoglobin in the blood is a definite and important indicator that blood sugar remains high over a long period of time. Therefore, an HbA1C test above normal indicates that diabetes patients have a high risk of developing retinopathy, nephropathy, and neuropathy, which are the most important complications associated with high blood sugar. While it is sufficient to perform the HbA1C test once a year in well-controlled diabetes patients, it may be necessary to repeat the test at more frequent intervals, such as 3 or 6 months, in patients with high results of this test or in whom blood sugar regulation has not been achieved. Since even a slight elevation in the HbA1C level may indicate the possibility of serious complications, it is of great importance that the test is repeated at regular intervals without neglect and that the results are meticulously evaluated by a specialist.

Although blood tests in diabetics and finger measurements using a needle give clear results, they only allow instant evaluation. Therefore, these tests may be insufficient in detecting conditions such as the prediabetes period (hidden sugar), which is also called the pre-diabetes period, and fluctuations in blood sugar that occur at night while sleeping. Therefore, the HbA1C test can be used safely in patients who have diabetes-related problems despite normal fasting blood sugar and provides clearer findings. HbA1C, a simple and practical blood test, can be safely applied at any time of the day, as it does not require fasting. Although it is called by different names such as glycated hemoglobin test, glycohemoglobin test, glycosylated hemoglobin test, all these have the same meaning and express the HbA1C test.

How does the HbA1C test work?

The answer to the question of what is HbA1C, which is the subject of the test, is glycosylated hemoglobin. Hemoglobins, the cells that give blood its red color, combine with glucose in individuals with high blood sugar and turn into glycosylated hemoglobins. This combination is because the body cannot use the sugar in the blood correctly and cannot carry it to the tissues. The amount of glucose combined with proteinaceous hemoglobin is directly proportional to the current level of blood sugar. Hemoglobins produced in the body have an average life span of 2 to 3 months. For this reason, by measuring the level of HbA1C in the blood, the average value of blood sugar levels for the 2-3 month period can be obtained. HbA1C has much higher accuracy than other blood glucose screenings because it reflects the average blood glucose level for a given period. It is usually repeated every 3 months in the beginning and every 6 months or once a year after blood sugar regulation is established to investigate the extent to which blood sugar control can be achieved in type 1 and type 2 diabetes patients. In healthy individuals without diabetes, approximately 5% of the hemoglobin in the blood is glycosylated. As a result of the hemoglobin A1C test, a slightly elevated value indicates prediabetes, and an increase indicates diabetes.

What ranges should the HbA1C values ​​be in?

In healthy individuals without diabetes, the blood HbA1C level is expected to be between 4.7% and 5.6%. If the hemoglobin A1C level is found to be between 5.7% and 6.4%, there is a hidden sugar condition, which is also called prediabetes. At this stage, decreases and increases in blood sugar may be at a level that cannot be detected by fasting blood glucose measurement or finger glucose measurement. In individuals who can be described as diabetics, the HbA1C level is above 6.5%. A table has been developed by the American Diabetes Association, which provides an average figure for the blood sugar level with the help of the hemoglobin A1C test results. By looking at this table, it can be easily determined that someone with a 6% HbA1C test result has a 3-month blood sugar average of 126, and someone with a 7% blood sugar average is 152 mg/dL. Results obtained in glycosylated hemoglobin tests have approximately a 0.5% margin of error. Therefore, it can be said that the HbA1C level of a patient with a test result of 6% is between 5.5% and 6.5%.

Chronic diseases or some medications may affect the results of the HbA1C test. Diseases such as kidney failure, liver diseases, or anemia that directly affect the level of hemoglobin in the blood may cause the test result to be incorrect. The same is true for some drugs used. For this reason, before the test is performed, patients should be asked whether they have any different chronic diseases and the drugs they use. Especially in type 1 diabetes patients, although there are fluctuations in blood sugar due to hypoglycemia that occurs from time to time due to the use of insulin, despite the increase in blood sugar, HbA1C tests may be normal because they reflect the average value. For such reasons, it should be known that the HbA1C test is not sufficient alone in blood sugar control and should be evaluated together with fasting blood sugar and oral glucose intolerance tests.

How to lower HbA1C?

The only way to lower the HbA1C level is to regulate blood sugar. For this, first of all, the treatment plan for diabetes patients should be clearly determined by the physician, and the patients should be directed to nutritionists to create a nutrition plan suitable for the drugs used or insulin injections. Diabetes education should be given in detail by multidisciplinary teams formed by physicians, nurses, and dietitians, and patients should be trained on carbohydrate counting. Hyperglycemia and hypoglycemia should be prevented by well-adjusting insulin doses in patients with insulin-dependent diabetes, taking into account their nutritional habits and physical activity levels. After the diagnosis of the disease and the regulation of blood sugar in type 2 diabetes patients, a process called the remission phase can be observed in which the blood sugar levels of the patients are within normal limits without using any medication. In this process, patients should be kept under constant control in terms of blood sugar levels, and they should be provided with the necessary training on finger blood glucose measurement at home. The target value for the HbA1C level in diabetes patients whose blood sugar control is achieved in this way is 6.5% and below. By keeping the hemoglobin A1C level below this value, complications such as nephropathy, neuropathy, retinopathy, and the risk of cardiovascular diseases that may develop due to diabetes can be significantly reduced.

If you are also a diabetic or have not completed your routine blood sugar tests yet, you should apply to a health institution and have the necessary examination and diagnostic tests done. If you have diabetes by getting an HbA1C test, you can find out if your 3-month blood sugar average is within the normal range, and if you have not received a diagnosis of diabetes, you can undergo screening for this disease. If any elevation is detected as a result of the tests to be performed, you can plan your treatment process together with your physician.


The page content is for informational purposes only. Items containing information about therapeutic health services are not included in the content of the page. Consult your physician for diagnosis and treatment.