The glycosylated hemoglobin test, also known as glycated hemoglobin, is a blood test that helps to identify and monitor the development of diabetes.
This test works because the sugar present in the blood binds to a component of red blood cells, hemoglobin, and remains linked until the red blood cell cycle, which lasts an average of 120 days, ends. Thus, the value of glycosylated hemoglobin allows to know the average amount of sugar in the last 3 months.
In this way, this test is more accurate than the simple finger prick test, which can be changed due to food and, therefore, is often used to diagnose diabetes. Find out what other tests are used to diagnose diabetes.
Reference values
The glycosylated hemoglobin values are for an adult:
- Normal: less than 5.7%; Diabetes: 6.5% or more.
These values can vary from laboratory to laboratory and therefore it is important that the interpretation of the test is done by the doctor who ordered the test.
Low glycated hemoglobin indicates hypoglycemia and its causes should be studied by the doctor.
How to prepare for the exam
Since this test assesses the amount of sugar bound to hemoglobin in the last 3 months, no preparation is required. Therefore, it is also not necessary to be fasting, since what you eat before the exam does not change the results, but what you ate during the last 3 months. However, if in addition to glycated hemoglobin, 24-hour glucose or cholesterol is requested, it is necessary to fast for at least 8 hours.
When to repeat the exam
In the case of being diagnosed with diabetes, the test must be repeated every 3 or 6 months to check whether the treatment is having the expected result or whether it is necessary to start another treatment option.
If the values are normal, the test should only be repeated when there is suspicion of having diabetes, which happens when symptoms such as frequent urge to urinate, excessive thirst or difficulty to heal, for example.
