The key difference between A1c and glucose is that A1c is the percentage of glycated hemoglobin (hemoglobin that is bound with glucose) in the blood, while glucose test is a fasting blood sugar test which is done by a glucometer.

The presence of glucose in the urine is an indication of diabetes. Measuring blood sugar can tell you whether you have prediabetes or type 2 diabetes. Prediabetes is the first stage of type 2 diabetes. Both prediabetes and type 2 diabetes are risky and can cause cardiovascular diseases too. In both cases, blood sugar levels are higher than the normal blood sugar level. There are different tests we can undergo in order to determine high blood sugar. A1c and blood glucose testing are two tests among them.

CONTENTS

1. Overview and Key Difference
2. What is A1C 
3. What is Glucose
4. Similarities Between A1C and Glucose
5. Side by Side Comparison – A1C vs Glucose in Tabular Form
6. Summary

What is A1C?

A1c, also known as hemoglobin A1c test, HbA1c test or glycosylated hemoglobin test, is a measurement of the percentage of blood glucose that is attached to the hemoglobin in the red blood cells. Moreover, the A1c test result reflects the average blood sugar over the past 2-3 months. Generally, the A1c test is used in the diagnosis of prediabetes and type 2 diabetes. But, this test does not need fasting before the test. It can be given at any time as a part of an overall blood screening. However, blood sugar meter cannot be used for the A1c test. Measuring A1c is a way to gauge long-term glucose control. People with diabetes must try to keep the A1c level under 7%.

Figure 01: A1c Test

If the result of the A1c test lies between 5.7% – 6.4 %, it tells that you have prediabetes. If it exceeds 6.5, it indicates the likeliness of having type 2 diabetes. In healthy people without diabetes, the A1c gives the result of 4% -5%.

What is Glucose?

Blood glucose is a test that measures the concentration of glucose in the bloodstream. Glucose can be measured in plasma, serum or whole blood. But, the most recommended is blood plasma for the blood glucose test since the nature of the specimen largely influences the glucose concentration in blood. Moreover, certain factors such as medications, acute stress, venous stasis, posture, and sample handling can affect the glucose concentration in blood.

Normal blood glucose test is done by drawing a sample after an overnight fast. Then the glucose in plasma is measured using a glucometer. After cleaning the side of a fingertip using an alcohol swab, it is necessary to make a small cut using a sterilized scalpel. Then a drop of blood is squeezed onto the test strip, and the strip is put into the monitor. The blood sugar meter measures our glucose concentration within a few seconds and gives the reading in milligrams of glucose per deciliter of blood (mg/dL). Therefore, it is an automated method which is inexpensive, easy and fast. Moreover, this test is available in most laboratories worldwide. People with diabetes may get their readings above 125+ mg/dL. When a person has diabetes, it is essential to undergo regular blood glucose tests and follow the correct treatment plan for diabetes.

Figure 02: Blood Glucose

In addition to normal fasting blood sugar test, there are several other non-fasting glucose tests as well. Random plasma glucose (RPG) and Oral glucose tolerance test (OGTT) are two such non-fasting tests.

What are the Similarities Between A1C and Glucose?

• A1c and blood glucose are two tests a doctor uses to diagnose and confirm diabetes.
• The regular A1c and glucose testing reveal whether the person’s treatment is working well or need some adjustments.
• Moreover, managing A1c and glucose is of utmost importance in order to prevent complications of diabetes, such as cardiovascular diseases.

What is the Difference Between A1C and Glucose?

Hemoglobin A1c test measures the percentage of glucose bound to red blood cells in the blood, while glucose test measures the milligrams of glucose per deciliter of blood. So, this is the key difference between A1c and glucose. Blood sugar meters can’t check for hemoglobin A1c, but they can check blood glucose.

Moreover, glucose tests require fasting before the test, while the A1c test does not require fasting before the test. Thus, this is another difference between A1c and glucose. In an A1c test, it is necessary to take some blood and send it to the laboratory for assessment. But, in glucose test, it is necessary to squeeze a drop of blood onto the test strip and put the strip into the monitor. Furthermore, A1c measures in percentage while glucose test measures blood sugar in mg/dL.

Below infographic summarizes the difference between A1c and glucose.

Summary – A1C vs Glucose

A1c and glucose are two tests that will help doctors to diagnose diabetes in a patient. A1c measures the glucose that is bound to hemoglobin in red blood cells. Glucose test measures the glucose concentration in milligrams of glucose per deciliter of blood. Importantly, the A1c test does not require fasting, but glucose test requires fasting overnight. Moreover, a glucometer is used to measure blood glucose, while glucometer can’t tell your A1c. HbA1c is the main test used to manage diabetes since it measures how the body is managing blood sugar over time, usually the last 2–3 months. However, doctors use both methods to diagnose and confirm diabetes. Thus, this concludes the discussion on the difference between A1c and glucose.

Reference:

1. Sacks, David B. “A1C Versus Glucose Testing: A Comparison.” Diabetes Care, American Diabetes Association, 1 Feb. 2011, Available here.
2. MacGill, Markus. “The A1C Test: Uses, Procedure, and Target Levels.” Medical News Today, MediLexicon International, 27 Mar. 2019, Available here.

Image Courtesy:

1. “Altus AFB lab test 120110-F-FV476-045” By Airman 1st Class franklin ramos – (Public Domain) via Commons Wikimedia
2. “Blood Glucose Testing” By David-i98 (CC BY-SA 3.0) via Commons Wikimedia

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