What is glycosylated haemoglobin?

Haemoglobin is a protein that resides in the blood, particularly red blood cells. This protein contains iron and is responsible for carrying oxygen to the cells in the body, thereby allowing the flow of energy in the body. It also carries carbon dioxide from the cells to the lungs. The pigment is what gives blood its red hue.

Glycosylated hemoglobin is a haemoglobin molecule that forms a chemical covalent bond with sugar, i.e., the glucose present in the body. It is also known as Glycated haemoglobin, which is the technically correct term since glycosylated is used to refer to a substance that is a product of a chemical reaction between a carbohydrate biomolecule and another biomolecule that is compatible. This reaction is catalyzed by an enzyme. On the other hand, Glycated denotes a covalent bond that is formed between a protein and a sugar molecule. Hemoglobin A1c or HbA1c are common terms used for glycosylated hemoglobin.

Why should you worry about glycosylated haemoglobin levels?

A sugar and haemoglobin bonding or linking is permanent. The more the number of glycated haemoglobin levels, the more the sugar level in the blood. When the level reaches too high, it connotes diabetes. A glycosylated haemoglobin test is used to monitor its levels in the bloodstream.

What is a glycosylated haemoglobin test exactly?

It is a simple blood test used for assessment and diagnostic measures. The test reveals the average sugar levels of the blood for the past 3 months. The cap is put at three because each haemoglobin molecule has a maximum life span of four months, and the life of individual haemoglobin varies. Moreover, more than 50% of haemoglobin undergoes the process after 90 days.

A glycosylated haemoglobin test is considered one of the most trustworthy tests to diagnose blood sugar levels because it is easier to detect glucose-haemoglobin bonds than others. The results tell the percentage of HbA1c molecules. Here is a general guideline to decipher the results:-

  • If the level is 5% to 6%, the person is considered non-diabetic.
  • A person is considered prediabetic or vulnerable to diabetes if the percentage is between 5.7% and 6.4%.
  • The range of 6.5 to 7% is indicative of controlled diabetes mellitus, while above that, the diabetes level must be regulated.
  • Having the level reach 8% and beyond needs immediate attention.

What do your results say?

As mentioned in the preceding sections, an elevated amount of glycosylated haemoglobin reveals whether one has diabetes mellitus or not. It also indicates whether the person is at risk of developing diabetes or not.

It is interesting to note that the levels may reveal different information when the method of measuring varies. For instance, when ion-exchange chromatography is used, the high level might indicate kidney failure. On the other hand, the levels are normal when the thiobarbituric acid method is used.

When should you get the test?

A glycosylated haemoglobin test is mandatory for a diabetes patient. They should take the test every 3-4 months or at least thrice a year. If someone is prediabetic, they might need the test every 6-8 months, ideally, twice a year. This is done for monitoring blood sugar levels and keeping them steady. The test must be avoided during pregnancy.

The test is also used to make a diagnosis. Hence, the practitioner recommends the tests when:

  1. The patient reports blurry vision without having any changes in eye vision.
  2. Extreme exhaustion or fatigue is accompanied by dizziness
  3. Unusual frequent urination.
  4. Family history of diabetes mellitus.
  5. Sudden vulnerability to infections
  6. High blood pressure.

One might get a test done if they have heart diseases or are obese since both f these make a person vulnerable to diabetes mellitus. 

What to know before you take the test.

The levels are considered reliable and valid when:-

  • The person has not donated blood for the past three months or had any blood loss.
  • If the person has any genetic difference in their haemoglobin composition, the standard measures are not viable to detect diabetes. For instance, people with sickle cell disease.
  • If the person’s red blood cells die before completing 120 days of life, the tests will indicate a low level of HbA1c glucose level. Anemics will thus have a low concentration of glycosylated hemoglobin. 
  • If the patient has made any changes in dietary habits in the past 5-6 weeks, the tests are deemed invalid.
  • Some patients’ levels of blood sugar experience highs and lows throughout the day. Due to this instability, the test results can become redundant.
  • Autoimmune hemolytic anemia makes it impossible to detect HbA1c. 

How is the glycosylated haemoglobin test done?

The test can be done in two ways depending on the availability of machines:

  • A1c machine: A blood drop is taken from the fingertip of the patient and put into the machine that can provide results within minutes.
  • Lab test: Here, the patient visits a lab where about 3ml of blood is extracted from the upper arm through a needle. The process is painless more or less and is conducted by a phlebotomist.

By Manali

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