average blood glucose

What is HbA1c?

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A common test that is performed when managing diabetes is the “HbA1c” test.

HbA1c is also called “glycated hemoglobin” or “glycosylated hemoglobin.” It’s a type of test that looks at how well blood sugar is controlled over time.

Here, we take a brief look at what this test means.

What is HbA1c?

HbA1c is a test that is performed that will give the patient and the doctor an idea as to how well blood sugars are being controlled.

Normally, hemoglobin in the blood stream carries oxygen to the vital tissues, nourishing them. When blood glucose levels are high, the glucose binds to the hemoglobin, which leads to “glycation.” The higher the glucose levels over prolonged periods of time, the higher the HbA1c.

What Is The Importance Of HbA1c?

HbA1c will provide information on how well blood sugar has been controlled over a period of 2 to 3 months. It is essentially an average value of blood sugar over 2 to 3 months.

In patients without diabetes, the normal level of A1c is between 4% and 6%. Levels higher than 6% indicate high blood sugars and possibly diabetes.

According to the definition of diabetes, an A1c level of over 6.5% combined with high fasting and postprandial sugars is diabetes.

How is HbA1c tested?

Levels can be easily checked with a blood test. The sample does not need to be a fasting sample and can be taken at any time of the day.

What Are The Advantages Of HbA1c Measurements?

  1. It can help diagnose prolonged episodes of high blood sugar, even if the fasting sugar is normal on the day of the test.
  2. It provides information on how well a patient is able to keep their blood sugar under control with treatment measures. Ideal control is achieved when A1c levels are below 6.5%.
  3. A high A1c level is more closely related to the development of complications than a fasting sugar. This means that if the A1c level is high, you are at risk of developing complications from diabetes.
  4. A fasting sample is not needed to measure A1c levels.
  5. A1c level measurement is not affected by what the patient has eaten on the day and what exercise has been done on the day the blood sample is tested.
  6. Testing A1c may work out cheaper in the long run as compared to periodic fasting and post-prandial sugar checks. Of course, this depends on the number of glucose level tests that are done.

Despite these advantages, HbA1c alone is not sufficient to make a diagnosis of diabetes. Furthermore, values may vary from lab to lab. A 0.5% variability between labs is quite common.

Limitations Of HbA1c Measurements

Due to how long red blood cells live, people with sickle cell anaemia, thalassemia, anaemia, kidney failure, liver disease, or who get blood transfusions can have different results. When measuring HbA1c in these people, it is important to be careful and use plasma glucose samples to confirm the diagnosis.

A falsely low HbA1c value can be caused by high altitude, bleeding, a blood transfusion, taking erythropoietin injections, taking iron supplements, having kidney or liver disease, being an alcoholic, having sickle cell anemia, or having spherocytosis.

Depending on how the HbA1c level is measured, taking vitamin C supplements can either raise or lower it.

On the other end of the spectrum, a falsely high HbA1c can be caused by a lack of available iron in the blood. This condition can be caused by iron deficiency anemia, and anaemia caused by an infection or a tumour. The lack of vitamin B12 can also make the HbA1c number look too high.

Closing Remarks

If you have diabetes, then make sure you get your HbA1c tested once every 3 months to ensure your sugar levels are under control.

Dr Vivek Baliga B
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