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Dr. Betina Chandolia

BDS, MDS - Oral Pathology and Microbiology

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Dr. Ashish Ranjan

MBBS, MD (Pharmacology)

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Glycosylated Hemoglobin

(HbA1c)

You need to provide

Blood

This test is for

Male, Female

Test Preparation

No special preparation required

Overview

What is HbA1c?

A glycosylated Hemoglobin (HbA1c) is a lab test to measure how much sugar has been in your blood over the past 2-3 months. It is used to detect prediabetes, diagnose diabetes as a part of health checkups, and monitor treatment efficacy. HbA1c values are considered normal if <5.7%, while values ≥ 6.5% are indicative of diabetes.

The higher the HbA1c, the greater the risk of complications. People having diabetes should take this test regularly to monitor their glucose levels and regulate the treatment decision. A proper schedule of exercise, healthy eating, and medication can assist in bringing down the level.

Why is HbA1c done?

The Glycosylated Hemoglobin test is performed to:

Monitor Diabetes treatment efficacy by measuring glycosylated hemoglobin regularly
Screen for Diabetes as part of regular health checkup, as well as in patients with high risk of developing diabetes
Diagnose and confirm diabetes with a combination of other tests if blood sugar levels have been high over a long period of time

What does HbA1c Measure?

Glycosylated Hemoglobin Test measures the percentage of glycosylated hemoglobin in blood which reflects the average blood glucose over a period of past two to three months (8 - 12 weeks).

Hemoglobin is the protein found in Red Blood Cells and is responsible for transporting oxygen. Of the different types of hemoglobin, Hemoglobin A is predominant. With the elevation of blood sugar levels, some glucose binds spontaneously to Hemoglobin A (this binding is called Glycosylation or Glycation) and remains bound for the complete lifetime of the RBC, which is 120 days normally. Higher the level of glucose in the blood, greater is the amount of it binding to Hemoglobin A. Hemoglobin A1c is the dominant form of Glycated Hemoglobin. As RBCs die and are replaced, Hemoglobin A1c is cleared and slowly replaced with non-glycosylated hemoglobin. Measurement of HbA1c level over a period of time gives an indication of the level of glucose in the blood over the specified period of time. This helps in the diagnosis of Diabetes and is useful for monitoring the effectiveness of measures taken to reduce blood sugar levels.

Interpreting HbA1c 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 level 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

Frequently Asked Questions about Glycosylated Hemoglobin

Q. Can the ABG values be same for two people?

HbA1c measurement gives an average of blood sugar value for past 3 months. The average blood glucose value (ABG) is a calculated parameter from the reported HbA1c value. If HbA1c is same for two people then ABG will automatically be the same.

Q. Is there any preparation required before the test?

Inform the doctor about the medications you may be taking. No other specific preparations are usually required before this test.

Q. What are the symptoms of Hyperglycemia?

Symptoms of Hyperglycemia include: Increased thirst, frequent urge to urinate, weakness, tiredness (fatigue), blurring of vision and slow wound healing.

Q. What is Hyperglycemia?

Hyperglycemia refers to a condition where the blood glucose level is above the normal range. This condition may indicate prediabetes or diabetes and may cause significant health problems.

Q. What is Hypoglycemia?

Hypoglycemia is the condition where the blood sugar levels fall below normal. This is commonly found in case of nutritional deficiency.

Q. What are the symptoms of Hypoglycemia?

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

Q. Can factors other than hormones and diet affect my blood sugar levels?

Yes, blood sugar levels can be increased by certain medications, during pregnancy, and even temporarily due to stress.

Q. When can false results appear in the Glycated Hemoglobin Test?

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

Q. When is the Hemoglobin A1c 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 level. 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 lower amount of Hemoglobin A in their blood.

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: Urine Glucose Test, Blood Glucose - Post prandial (PP), Random Blood Glucose Test, Fasting Blood Glucose Test and Oral Glucose Tolerance Test.

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

The blood glucose tests are performed to directly measure the concentration of glucose 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?

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 prevents 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 level reduces the risk of death due to cardiovascular diseases by 45%.

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 having been diagnosed with hypertension. Other reasons which 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. How is the blood sample taken?

The healthcare provider takes a blood sample from the arm. The site from where the blood is to be withdrawn is cleaned with a swab of rubbing alcohol. This is then followed by inserting a small needle which has a tube attached to it for collecting blood. Once the sufficient blood for analysis is withdrawn, the needle is removed. The site is then covered with a gauze pad.

Q. Is there any risk associated with the withdrawal of blood sample procedure?

As such there is no risk but in few cases, bruising, bleeding, and infection at the puncture site can be seen. In very few cases, there can be swelling of the vein after the blood is withdrawn.

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.

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