What Is the A1C Test?
The A1C test — also called the HbA1c, glycated hemoglobin, or glycohemoglobin test — measures your average blood sugar (glucose) level over the past two to three months. Unlike a fasting glucose test, which captures your blood sugar at a single moment, the A1C gives your doctor a long-term view of blood sugar control. It's the standard test used to diagnose prediabetes and diabetes, and to monitor how well diabetes management is working over time.
The result is reported as a percentage. Here's exactly what that percentage means.
A1C Result Ranges Explained
Below 5.7% is considered normal. It means your average blood sugar has been in a healthy range over the past three months.
5.7% to 6.4% indicates prediabetes. This is a warning zone. Your blood sugar is higher than normal but not yet high enough to be classified as type 2 diabetes. People with prediabetes have a significantly elevated risk of developing diabetes within 10 years — but lifestyle changes can often reverse the trend.
6.5% or above on two separate tests diagnoses type 2 diabetes. At this threshold, blood sugar levels have been high enough long enough to pose a risk of diabetic complications including nerve damage, kidney disease, and eye problems.
For people already diagnosed with diabetes, target A1C levels vary by individual. Most guidelines recommend a target below 7% for many adults with diabetes, though your doctor may set a different target based on your age, health status, and risk of hypoglycemia.
What Your A1C Percentage Means in Average Blood Sugar
A1C percentages can be converted to an estimated average glucose (eAG) in mg/dL:
- 5%: ~97 mg/dL
- 6%: ~126 mg/dL
- 7%: ~154 mg/dL
- 8%: ~183 mg/dL
- 9%: ~212 mg/dL
- 10%: ~240 mg/dL
This conversion helps bridge the gap between your lab report and your day-to-day glucose readings if you use a home monitor. For more context on how blood sugar values fit into your broader metabolic picture, see our CMP results guide.
Factors That Can Affect A1C Accuracy
The A1C test isn't perfect. Several conditions can make results higher or lower than your actual average blood sugar:
Conditions that falsely lower A1C:
- Hemolytic anemia (red blood cells are destroyed faster than normal, reducing exposure time to glucose)
- Iron deficiency anemia (when treated, A1C may rise temporarily)
- Recent blood transfusion
- Certain hemoglobin variants (particularly relevant for people of African, Mediterranean, or Southeast Asian descent)
Conditions that falsely raise A1C:
- Iron deficiency anemia (before treatment)
- Vitamin B12 deficiency
- Kidney failure
- Spleen removal
If your doctor suspects an inaccurate result, they may order a fructosamine test or use continuous glucose monitoring data instead. This is worth discussing if your A1C doesn't seem to match your home glucose readings.
Why A1C Matters Beyond Diabetes
Even if you haven't been diagnosed with diabetes, your A1C is a useful metabolic health marker. Research increasingly shows that blood sugar dysregulation — even in the prediabetes range — is associated with cardiovascular risk, cognitive decline, and chronic fatigue. Many people with prediabetes have no symptoms at all, which is why regular screening is important.
If your A1C has risen from one test to the next, that's a trend worth discussing with your doctor even if you're still in the "normal" range. Tracking lab trends over time can reveal a gradual upward drift that a single test might miss.
What to Do If Your A1C Is Elevated
A prediabetes or diabetes diagnosis can feel alarming, but it's important to know that lifestyle changes have a powerful effect on A1C. Clinical studies like the Diabetes Prevention Program found that modest weight loss (5–7% of body weight) and 150 minutes of moderate exercise per week reduced the risk of progression from prediabetes to diabetes by 58%.
Dietary approaches that reduce blood sugar spikes include:
- Reducing refined carbohydrates and sugary beverages
- Increasing fiber intake from vegetables, legumes, and whole grains
- Spreading carbohydrate intake evenly across meals
- Combining carbohydrates with protein and healthy fats to slow glucose absorption
For condition-specific guidance on diabetes and thyroid health, see our condition guides article.
Tracking Your A1C With MediSphere™
MediSphere™ stores your A1C history and plots it on a timeline, so you can see at a glance whether your blood sugar control is improving, stable, or worsening. The AI analysis explains what your specific percentage means in plain language and helps you generate relevant questions for your next appointment. Learn how AI-powered health insights can make your lab data more actionable — or visit the How It Works page to see the full MediSphere™ experience.
This article is for educational purposes only. Always discuss your specific results with your healthcare provider.