The glycosylated hemoglobin test, also known as HbA1c, is a blood test that helps identify and accompany the development of diabetes.
This test works because the sugar present in the blood binds to a component of the red blood cells, hemoglobin, staying together until the red blood cell cycle, which lasts on average 120 days, ends. In this way, 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 that of the finger picket, which can be altered by food and, therefore, is used many times for the diagnosis of diabetes.
The glycosylated hemoglobin values for an adult are:
Normal: less than 5.7%;
Diabetes: equal to or greater than 6.5%.
These values may vary from laboratory to laboratory and that is why it is important that the interpretation of the exam be made by the doctor who requested the exam.
Low glycosylated hemoglobin indicates hypoglycemia and its causes should be studied by the doctor.
How to prepare for the exam
Since the test evaluates the amount of sugar bound to hemoglobin in the last 3 months, no preparation is necessary. Therefore, it is not necessary to be fasting, because what you can eat before the test does not alter the results, but what you ate during the last 3 months. however, in addition to glycosylated hemoglobin 24 hours glucose or cholesterol is requested, it is necessary to fast for at least 8 hours.
When should the test be repeated?
In the case of being diagnosed with diabetes, the test must be repeated 3 or 6 months later to verify if the treatment is having the expected result or if it is necessary to start another treatment option.
If the values were normal, the test should be repeated only when there is suspicion of having diabetes, which happens when symptoms arise such as frequent urination, excessive thirst or difficulty healing, for example.