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HbA1c (Hemoglobin A1c)

Also known as Glycated hemoglobin test, Hemoglobin A1c, Glycosylated Hemoglobin

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This test is for

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Understanding HbA1c (Hemoglobin A1c)

What is HbA1c (Hemoglobin A1c)?

An HbA1c (Hemoglobin A1c) test, also known as a glycosylated hemoglobin test, measures the average amount of sugar in the blood over 2-3 months. This test helps diagnose diabetes and monitor its treatment. It is typically done as part of routine health checkups.

Diabetes is a chronic condition that affects the body's ability to process blood sugar properly, leading to high blood sugar levels. The signs and symptoms of diabetes can include increased thirst, frequent urination, blurred vision, fatigue, and slow healing of wounds. However, some individuals with diabetes may not experience any symptoms at all. Hemoglobin, a protein found in red blood cells, carries oxygen throughout the body. When glucose (sugar) molecules in your bloodstream attach to hemoglobin, a process called glycation occurs that causes the formation of glycosylated hemoglobin or HbA1c.

An HbA1c (Hemoglobin A1c) test provides an overall picture of your long-term blood sugar control, making it essential for managing diabetes. This test can help diagnose and monitor prediabetes and diabetes, allowing for early intervention and treatment to prevent or delay the onset of complications such as nerve damage, kidney disease, and vision problems.

The American Diabetes Association (ADA) recommends an HbA1c target of less than 7% to reduce the risk of complications. Individual targets may vary based on factors such as age, duration of diabetes, and the presence of other health conditions.

No special preparation is required before taking an HbA1c test. Test result ranges are approximate and may differ slightly between labs depending on the methodology and laboratory guidelines. Talk to your doctor about your specific test results. Narrate your complete medical history to help them correlate your clinical and laboratory findings. The test results will help the doctor determine your medical condition, recommend lifestyle modifications such as diet and exercise, decide whether or not medications are required to manage your condition and formulate your overall treatment plan.

What is HbA1c (Hemoglobin A1c) used for?

An HbA1c test can be done:

As part of routine health check-ups to estimate average blood glucose levels.
If you have symptoms of altered blood glucose levels such as weight gain, weight loss, blurred vision, frequent urge to urinate, or confusion.
For assessing risk for diabetes and prediabetes and for monitoring diabetes treatment.
To screen pregnant women for gestational diabetes.

What does HbA1c (Hemoglobin A1c) measure?

An HbA1c (Hemoglobin A1c) test precisely measures the percentage of sugar-coated or glycated hemoglobin in your blood. The test results represent the proportion of hemoglobin in your blood that has been glycated.

Hemoglobin, a vital protein found in red blood cells, is responsible for transporting oxygen throughout the body. Hemoglobin A is the most abundant form of hemoglobin, and when blood sugar levels increase, a higher proportion of hemoglobin A becomes glycated. As red blood cells have a lifespan of approximately 120 days, the sugar molecules remain attached to the hemoglobin for the duration of the cell's life. Consequently, the HbA1c test offers insight into your average blood sugar levels over the past 8 to 12 weeks.

Interpreting HbA1c (Hemoglobin A1c) results

Interpretations

Normal: Below 5.7% (39 mmol/mol approx.)

Prediabetic: 5.7% - 6.4% (39 to 46 mmol/mol approx.)

Diabetic: Above 6.5% (above 48 mmol/mol approx.)

Less than 5.7% Glycated Hemoglobin indicates normal levels of blood sugar. Increased risk of developing Diabetes is found in Prediabetic patients with blood sugar levels between 5.7% and 6.4%. Patients with a HbA1c level greater than 6.5% are usually diagnosed with Diabetes.

Answers to Patient Concerns & Frequently Asked Questions (FAQs) about HbA1c (Hemoglobin A1c)

Frequently Asked Questions about HbA1c (Hemoglobin A1c)

Q. Why is an HbA1c test performed?

An HbA1c test helps to measure a person's average blood sugar levels over the past 8 to 12 weeks. This test is essential for diagnosing and monitoring diabetes, assessing the effectiveness of diabetes treatment plans, and helping to prevent or manage potential complications.

Q. How often should I get an HbA1c test done?

An HbA1c test can be done as part of a routine health check-up. For individuals with diabetes, it's generally recommended to get this test done every 3 to 6 months, depending on your specific treatment plan and blood sugar control. If you have been recently diagnosed or have made significant changes to your treatment, your doctor may recommend more frequent testing.

Q. Can an HbA1c test be used for both Type 1 and Type 2 diabetes?

Yes, an HbA1c test is suitable for monitoring blood sugar control in individuals with both Type 1 and Type 2 diabetes. This test provides valuable information to the doctor, allowing them to assess the effectiveness of treatment plans and make necessary adjustments to optimize blood sugar control.

Q. What factors can affect the accuracy of an HbA1c test?

Certain factors such as anemia, recent blood transfusions, pregnancy, or specific genetic variants can potentially affect the accuracy of an HbA1c test. If you have any concerns about the reliability of your test results, consult the doctor, who may recommend additional testing or adjustments to your treatment plan.

Q. Is there any risk associated with the Hb1Ac test?

There is usually no risk associated with this test. However, some people may feel a slight sting while the needle is pricked and may experience some bleeding that is normal and usually not bothersome. Some people may experience slight swelling or bruising at the site of the needle prick. Applying ice 3-4 times daily for about a week may help reduce swelling and bruising. If it does not get better, consult your doctor.

Q. Can my HbA1c be normal/low despite high blood sugar levels?

Yes, it is possible for someone's HbA1c level to be normal or low, despite having high blood sugar levels. This is because HBa1c is a measure of average blood sugar levels over a period of two to three months, rather than a measurement of current blood sugar levels.

Q. What are the symptoms of hypoglycemia?

Symptoms of hypoglycemia include: Excessive sweating, frequent hunger, shivering or trembling, confusion and blurring of vision

Q. What are the risk factors for diabetes?

Diabetes can be caused by various reasons. The most common risk factors for diabetes include being obese or overweight with low physical activity, having a blood relative diagnosed with diabetes, or being diagnosed with hypertension. Other reasons that can cause diabetes could be low high-density Lipoproteins or high triglyceride levels, being diagnosed with Polycystic Ovarian Syndrome, or having been diagnosed with gestational diabetes and cardiovascular diseases.

Q. When can false results appear in the HbA1c test?

False results can appear in patients with hemolysis, anemia, and iron deficiency. False results may also appear in patients who have undergone blood transfusion recently.

Q. When is the HbA1c test insufficient to determine elevated blood sugar levels?

The HbA1c test cannot determine acute changes in blood glucose levels that trigger a glucose shock. It also cannot determine any recent change in blood glucose levels. The test is also insufficient to determine elevated blood sugar levels in people with variant hemoglobin like Hemoglobin S or Sickle Cell Hemoglobin since they have a lower amount of Hemoglobin A in their blood.

Q. What are the common complications of diabetes?

Diabetes causes an increase in blood sugar levels. Increased sugar levels, if not controlled, can cause severe damage to the muscles and nerves. This may give rise to a number of complications over a period of time. Some common complications of uncontrolled diabetes include heart diseases like coronary artery disease, heart attack, diabetic retinopathy (damage to the retina) which may cause blindness, diabetic neuropathy (damage to the nerves) at various parts of the body. It may also cause diabetic nephropathy (damage to the kidneys) resulting in chronic loss of kidney function and diabetic foot which can cause foot ulcers that may turn gangrenous. Apart from these, uncontrolled diabetes may also lead to other severe conditions like hearing impairment, a number of skin conditions, and may even lead to death.

Q. What other tests can be prescribed by your doctor in case of abnormal result?

Additional tests that may be prescribed to diagnose diabetes in case of abnormal results are the urine glucose test, Blood Glucose - Post prandial (PP) test, Random Blood Glucose Test, Fasting Blood Glucose Test, and Oral Glucose Tolerance Test.

Q. Can the average blood glucose value (ABG) values be same for two people?

HbA1c measurement gives an average blood sugar value for the past three months. The average blood glucose value (ABG) is a calculated parameter from the reported HbA1c value. If HbA1c is the same for two people, then ABG will automatically be the same.

Q. How is the HbA1c test different from blood glucose test?

The blood glucose tests are performed to directly measure the glucose concentration in your blood at the time of testing (single point in time). The HbA1c test indicates the trend of your blood glucose levels over a period of time (8-12 weeks), similar to an average, by measuring the percentage of glycated hemoglobin persisting in blood.

Q. What are the benefits of lowering your HbA1c level?

A lowered HbA1c level is an indication of sustained lowered or reduced blood glucose levels over a period of time. Long-term reduced blood glucose levels in diabetic patients successfully prevent future complications of diabetes, including kidney complications, nerve damage, damage to the retina, cardiovascular diseases, and diabetic foot, among others. Research has shown that a reduction of just about 1% in HbA1c levels reduces the risk of death due to cardiovascular diseases by 45%.

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References

Sherwani SI, Khan HA, Ekhzaimy A, Masood A, Sakharkar MK. Significance of HbA1c Test in Diagnosis and Prognosis of Diabetic Patients. Biomark Insights. 2016 Jul 3;11:95-104. [Accessed 22 May 2023]. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4933534/

Your Diabetes Care Schedule [Internet}. CDC; 19 Apr. 2023 [Accessed 22 May 2023]. Available from: https://www.cdc.gov/diabetes/managing/care-schedule.html

Unnikrishnan R, Anjana RM, Mohan V. Drugs affecting HbA1c levels. Indian J Endocrinol Metab. 2012 Jul;16(4):528-31. [Accessed 22 May 2023]. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3401751/