HbA1c Test
The HbA1c test, also known as the hemoglobin A1c or glycated hemoglobin test, is a blood test that measures the average level of glucose (sugar) in the blood over the past 2 to 3 months.
Purpose of the Test
The HbA1c test is used to:
- Diagnose diabetes and prediabetes
- Monitor the effectiveness of diabetes treatment plans
- Assess the risk of developing complications related to diabetes, such as heart disease and kidney damage
How the Test Works
Hemoglobin is a protein in red blood cells that carries oxygen to different parts of the body. When glucose is present in the blood, it binds to hemoglobin, forming glycated hemoglobin (HbA1c). The more glucose in the blood, the more HbA1c is formed.
The HbA1c test measures the percentage of glycated hemoglobin in the blood. This percentage reflects the average level of glucose in the blood over the past 2 to 3 months, which is the lifespan of a red blood cell.
Interpretation of Results
The results of the HbA1c test are interpreted as follows:
- < 5.7%: Normal
- 5.7% to 6.4%: Prediabetes
- = 6.5%: Diabetes
For people with diabetes, the American Diabetes Association recommends the following HbA1c targets:
- < 7% for most adults
- < 7.5% for adults with a history of severe hypoglycemia or limited life expectancy
- < 8% for adults with significant comorbidities or extensive insulin use
Limitations and Precautions
The HbA1c test has some limitations and precautions:
- It may not be accurate in people with certain medical conditions, such as anemia or kidney disease
- It may not reflect recent changes in blood glucose levels
- It should not be used to diagnose diabetes in people with conditions that affect red blood cell lifespan, such as hemolytic anemia
Preparation and Procedure
No special preparation is required for the HbA1c test. A healthcare provider will take a blood sample from a vein in the arm using a needle and syringe or a fingerstick device.
The blood sample is then sent to a laboratory for analysis, where the percentage of glycated hemoglobin is measured using specialized equipment.
Article last updated on: 6th June 2025.
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