Convert HbA1C to Estimated Average Glucose (eAG)
Enter your HbA1c percentage below to convert it to your estimated average daily glucose level.
What is Hemoglobin A1C?
Hemoglobin A1c (often abbreviated as HbA1c or simply A1C) is a standard clinical blood test used to monitor glycemic control. Glucose in your blood attaches to hemoglobin, a protein inside red blood cells, in a process called glycation. Because red blood cells have an average lifespan of about 120 days (4 months), the A1C test measures what percentage of your hemoglobin is coated with sugar, reflecting your average blood sugar levels over the past 2 to 3 months.
Unlike daily finger-stick blood glucose checks or Continuous Glucose Monitors (CGM), which show blood sugar levels at a single moment in time, the A1C test provides a longer-term, more stable picture of glucose management.
A1C Diagnostic Categories
The American Diabetes Association (ADA) defines the standard diagnostic categories as follows:
| A1C Percentage | Classification | Clinical Interpretation |
|---|---|---|
| Below 5.7% | Normal (Non-Diabetes) | Optimal glucose regulation across the red blood cell lifespan. |
| 5.7% – 6.4% | Prediabetes | Indicates insulin resistance and high risk of developing type 2 diabetes. |
| 6.5% or Higher | Diabetes Range | Consistent with a diabetes diagnosis, requiring clinical confirmation and evaluation. |
The A1C to eAG Conversion Formula
Estimated Average Glucose (eAG) is calculated using a linear regression formula developed in the ADAG (A1C-Derived Average Glucose) study. The mathematical formula is:
eAG (mg/dL) = (28.7 × A1C) - 46.7
To convert the result to international units (mmol/L), the eAG value in mg/dL is divided by 18:
eAG (mmol/L) = eAG (mg/dL) / 18
These formulas are recognized by the American Diabetes Association (ADA) and the European Association for the Study of Diabetes (EASD) to help patients understand how A1C results correspond to self-monitoring measurements.
What to Track & Monitor
If you are managing blood glucose levels or monitoring diabetes, track these metrics to share with your clinician:
- A1C Lab Dates: Track your values over time. Most adults with diabetes or prediabetes have their A1C checked every 3 to 6 months.
- Daily Glucose Ranges: Log fasting glucose levels (taken immediately upon waking) and postprandial glucose levels (taken 1 to 2 hours after a meal) using a home glucometer.
- Dietary Habits: Keep a food log tracking carbohydrate intake, as carbohydrates have the most direct impact on blood glucose.
- Physical Activity: Note daily exercise. Muscle contractions draw glucose from the blood for energy, improving insulin sensitivity.
- Physical Symptoms: Record symptoms like extreme thirst, frequent urination, fatigue, blurred vision, or unexplained weight loss.
When to Speak with a Doctor
Consult a healthcare professional regarding your blood sugar levels in the following circumstances:
- Your A1C test result is 5.7% or higher, so your doctor can evaluate your risk and discuss preventive lifestyle adjustments.
- You experience symptoms of high blood sugar (hyperglycemia), such as excessive thirst, frequent urination, fatigue, or slow-healing cuts.
- You experience symptoms of low blood sugar (hypoglycemia), such as shaking, sweating, rapid heartbeat, dizziness, or confusion.
- You are pregnant or planning a pregnancy, as tight blood sugar control is crucial for maternal and fetal health.
- You have conditions like anemia, kidney disease, or sickle cell trait, which can alter red blood cell lifespans and lead to inaccurate A1C test results.
Frequently Asked Questions
Hemoglobin A1c (HbA1c or simply A1C) is a blood test that measures the average blood sugar (glucose) levels over the past 2 to 3 months. It represents the percentage of hemoglobin—a protein in red blood cells—that is coated with sugar (glycated).
Estimated Average Glucose (eAG) is a translation of your A1C percentage into units similar to daily finger-stick blood glucose readings (measured in mg/dL or mmol/L). It helps patients better relate their A1C test scores to their day-to-day self-monitoring results.
For individuals with stable glycemic control meeting treatment goals, testing twice a year is typically recommended. For those making changes to therapy or not meeting goals, testing every 3 months is standard. Consult a healthcare provider for your personalized schedule.
