What Is an A1C?
An A1C is a blood test that gives an estimate of your average blood sugar over about the past 3 months. It is commonly used to screen for prediabetes and diabetes and to monitor blood sugar control in people who already have diabetes.
How does an A1C work?
When sugar is in your bloodstream, some of it attaches to hemoglobin, a protein in red blood cells. The A1C test measures the percentage of red blood cells with sugar attached. Because red blood cells live for about 3 months, the A1C gives a longer-term view of blood sugar patterns.
What do A1C results mean?
Common A1C categories include:
Below 5.7%: generally considered normal
5.7% to 6.4%: prediabetes range
6.5% or higher: diabetes range when confirmed appropriately
The NIDDK also describes A1C as a blood test that provides information about average blood glucose over the past 3 months.
Why A1C matters
A1C can help identify blood sugar problems before symptoms become obvious. Prediabetes and early type 2 diabetes may not cause noticeable symptoms at first.
A1C may be useful if you have:
Family history of diabetes
Weight concerns
High blood pressure
High cholesterol
History of gestational diabetes
PCOS
Increased thirst
Frequent urination
Blurry vision
Fatigue
Slow wound healing
A1C vs. fasting glucose
A fasting glucose shows your blood sugar at one point in time. An A1C gives a longer-term estimate. Both can be useful, and sometimes additional testing is needed.
Can A1C be inaccurate?
Yes. Certain conditions can affect A1C accuracy, including some anemias, recent blood loss, pregnancy, kidney disease, liver disease, certain blood disorders, and conditions affecting red blood cells.
If your symptoms and A1C do not match, your provider may recommend additional testing.
How to improve A1C
Depending on your situation, A1C may improve with:
Weight loss if appropriate
More physical activity
Strength training
Higher protein intake
Higher fiber intake
Reducing sugary drinks
Better sleep
Stress management
Medication when appropriate
Regular follow-up
Can telehealth help?
Yes. Telehealth can help review A1C results, discuss diabetes or prediabetes risk, order follow-up labs when indicated, and create a practical plan for blood sugar improvement.
When to seek urgent care
Seek urgent care for severe weakness, confusion, fainting, severe dehydration, vomiting, trouble breathing, chest pain, or symptoms of very high or very low blood sugar.
Final thought
A1C is one of the most useful screening tools for blood sugar health. It can help identify risk early and guide lifestyle, medication, and follow-up decisions.
This information is for educational purposes only and does not replace medical advice, diagnosis, or treatment. If you are experiencing severe symptoms, signs of infection, severe allergic reaction symptoms, trouble breathing, or a medical emergency, call 911 or go to the nearest emergency room.
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