A Hemoglobin A1C (HbA1c) test shows your average blood sugar level over the past 2–3 months.
Doctors often use this test to:
Screen for diabetes or prediabetes
Monitor long-term blood sugar control
Look at trends rather than daily changes
Unlike a fasting glucose test, you do not need to fast for an A1C test.
This test looks at how much glucose has attached to hemoglobin in your red blood cells.
Because red blood cells live for about 3 months, A1C reflects:
Long-term blood sugar patterns
Overall glucose control
It does not change quickly from one day to the next.
A1C results are often grouped as:
Normal range
Prediabetes range
Diabetes range
Your lab report will show your exact value and the reference ranges used.
Higher A1C levels may be caused by:
Prediabetes or diabetes
Ongoing high blood sugar
Certain medical conditions
Medication effects
One result alone does not define your future health.
Low A1C levels are usually not concerning.
They may be seen with:
Frequent low blood sugar
Certain blood conditions
Recent blood loss
Low results rarely need treatment.
A1C levels can be affected by:
Recent illness
Anemia or blood disorders
Pregnancy
Changes in red blood cell lifespan
Doctors consider these factors when interpreting results.
Doctors may repeat this test:
Every few months to monitor trends
When adjusting treatment
If results are borderline
Watching changes over time is more important than one value.
A borderline or mildly elevated A1C is very common.
Many people improve their A1C with small, gradual lifestyle changes.
Hemoglobin A1C shows your average blood sugar over several months.
It’s a helpful long-term marker and works best when viewed as part of the full picture.
You may want to read:
Fasting Blood Glucose Explained
Insulin Blood Test Explained
Comprehensive Metabolic Panel (CMP) Explained
You can also use the navigation bar above to explore other blood test results.
This information is for educational purposes only and is not medical advice. Always talk with a healthcare professional about your results.