Patient Resource Articles

Glycosylated Hemoglobin (HbA1c) Test

Written and Published by Dr. Aniruddha Ranadive [Joint Managing Director @ Nucleus The Diagnostic Centre] on March 14, 2020
Hemoglobin A1c, also called A1c or glycated hemoglobin, is hemoglobin with glucose attached. The A1c test evaluates the average amount of glucose in the blood over the last 2 to 3 months by measuring the percentage of glycated hemoglobin in the blood.

 Hemoglobin is an oxygen-transporting protein found inside red blood cells (RBCs). There are several types of normal hemoglobin, but the predominant form – about 95-96% – is hemoglobin A. As glucose circulates in the blood, some of it spontaneously binds to hemoglobin A


Hemoglobin (HbA1c) Test


Why Get Tested?

To help determine whether you are at an increased risk of developing diabetes to help diagnose diabetes and prediabetes to monitor diabetes and to aid in treatment decisions

When To Get Tested?

As part of a health checkup or when you have risk factors for or symptoms of diabetes; after first diagnosis with diabetes, every 3-4 months or about 120 days to ensure that your glycemic goals are met and/or maintained or when your therapy plan has changed 

What is being tested?

An A1c test may be used to screen for and diagnose diabetes or risk of developing diabetes. Standards of medical care in diabetes from the American Diabetes Association (ADA) state that diabetes may be diagnosed based on A1c criteria or blood glucose criteria (e.g., the fasting blood glucose (FBG) or the 2-hour glucose tolerance test).

A1c is also used to monitor treatment for individuals diagnosed with diabetes. It helps to evaluate how well your glucose levels have been controlled by treatment over time. For monitoring purposes, an A1c of less than 7% indicates good glucose control and a lower risk of diabetic complications for the majority of people with diabetes.

How is the test used?

The hemoglobin A1c test may be used to screen for and diagnose diabetes and prediabetes in adults. 

When is it ordered?

A1c may be ordered as part of a health checkup or when someone is suspected of having diabetes because of classical signs or symptoms of increased blood glucose levels (hyperglycemia) such as:

  • Increased thirst and drinking fluids
  • Increased urination
  • Increased appetite
  • Fatigue
  • Blurred vision
  • Slow-healing infections

 What does the test result mean?

In screening and diagnosis, some results that may be seen include:

  • A person who does not have diabetes: A1c result less than 5.7% (39 mmol/mol)
  • Diabetes: A1c level is 6.5% (48 mmol/mol) or higher
  • Increased risk of developing diabetes in the future (pre-diabetes): A1c of 5.7% to 6.4% (39-46 mmol/mol)
     

For monitoring glucose control, A1c is currently reported as a percentage and, for most people with diabetes, it is recommended that they aim to keep their hemoglobin A1c below 7%. The closer they can keep their A1c to the American Diabetes Association (ADA)'s therapeutic goal of less than 7% without experiencing excessive low blood glucose (hypoglycemia), the better their diabetes is in control. As the A1c increases, so does the risk of complications.