General Practice 2022

Glycated hemoglobin: what é, what it is for and reference values ​​ê

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Glycated hemoglobin: what é, what it is for and reference values ​​ê
Glycated hemoglobin: what é, what it is for and reference values ​​ê

Glycated hemoglobin, also known as glycosylated hemoglobin or Hb1Ac, is a blood test that aims to assess glucose levels in the last three months before the test is performed. This is because glucose manages to be linked to one of the components of the red blood cell, hemoglobin, during the entire cycle of red blood cells, which lasts about 120 days.

Thus, the glycated hemoglobin test is requested by the doctor to identify diabetes, monitor its development or verify if the treatment of the disease is being effective, being done through the analysis of a small sample of blood collected in laboratory.

What is glycated hemoglobin for

The glycated hemoglobin test is performed with the aim of evaluating glucose levels in recent months, being useful in the diagnosis of diabetes. In addition, in the case of people who have already been diagnosed with diabetes, this test is useful to verify if the treatment is being effective or is being done correctly, because if it is not, a change in the result can be verified.

In addition, when the value of glycated hemoglobin is much higher than the normal considered by the laboratory, the person is more likely to develop complications related to diabetes, such as cardiac, renal or neuronal changes, for example. See what are the main complications of diabetes.

This test is more suitable than fasting glucose for the initial diagnosis of diabetes, because the glucose test can be influenced by changes in recent eating habits, not representing circulating sugar levels in recent months.Thus, it is possible that before taking the glucose test, the person has a he althier diet and low in sugar, so that fasting glucose may be within normal values, which may not represent the person's reality.

Thus, to make the diagnosis of diabetes, the fasting glucose test, glycated hemoglobin and/or the glucose tolerance test, the OGTT, is usually requested. Learn more about tests that help diagnose diabetes.

Reference values

The reference values ​​for glycated hemoglobin may vary according to the laboratory, however in general the values ​​considered are:

  • Normal: Hb1Ac between 4.7% and 5.6%;
  • Pre-diabetes: Hb1Ac between 5.7% and 6.4%;
  • Diabetes: Hb1Ac above 6.5% in two tests performed separately.

Furthermore, in people already diagnosed with diabetes, Hb1Ac values ​​between 6.5% and 7.0% indicate that the disease is under good control.On the other hand, Hb1Ac values ​​above 8% indicate that diabetes is not being properly controlled, with a higher risk of complications and a change in treatment.

The glycated hemoglobin test does not require any preparation, however, as it is usually requested together with the fasting glucose test, it may be necessary to fast for at least 8 hours.

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