🧬 What Is HbA1c?
HbA1c (Glycated Hemoglobin or Hemoglobin A1c) describes a hemoglobin particle that has bonded with a molecule of sugar. It is written as a percentage (%).
Hemoglobin (Hb) is a protein that transports oxygen — it's the most important part of a red blood cell.
When the body doesn't produce enough insulin, glucose concentration in the blood rises. With more sugar in the bloodstream, more sugar particles bond to hemoglobin, creating HbA1c. This is why we measure HbA1c to indirectly evaluate insulin function and check treatment compliance.
The condition caused by lack of insulin or its improper function is called diabetes mellitus, which can be treated with artificial insulin 💉 or oral medication 💊.
📊 What Is Estimated Average Glucose (eAG)?
Estimated average glucose (eAG) summarizes the blood glucose level during the past 3 months. We obtain it by transforming the HbA1c percentage to mg/dL or mmol/L.
Why 3 months? The average lifespan of a red blood cell is ~120 days (nearly 4 months), but to ensure most tested cells were alive during the measurement period, we use 3 months for accuracy.
📏 Normal Blood Sugar Levels
Healthy Individuals
| HbA1c | Status |
|---|---|
| 💚 < 5.7% | Normal |
| 🔶 5.7–6.4% | Prediabetes |
| 🔺 ≥ 6.5% | Diabetes |
Individuals with Diabetes
| HbA1c | Assessment |
|---|---|
| ✅ < 6% | Target for pregnant women with diabetes |
| ✅ < 6.5% | Excellent for general population |
| ✅ < 7% | Recommended for general population |
| ✅ < 8% | Good for people over 80 or with severe comorbidities |
| ❗ ≥ 7% | Too high for general population |
📋 HbA1c to Average Glucose — Conversion Chart
| HbA1c (%) | mmol/mol | eAG (mmol/L) | eAG (mg/dL) |
|---|---|---|---|
| 5 | 31 | 5.4 | 97 |
| 6 | 42 | 7.0 | 126 |
| 7 | 53 | 8.6 | 154 |
| 8 | 64 | 10.2 | 183 |
| 9 | 75 | 11.8 | 212 |
| 10 | 86 | 13.4 | 240 |
| 11 | 97 | 14.9 | 269 |
| 12 | 108 | 16.5 | 298 |
| 13 | 119 | 18.1 | 326 |
| 14 | 130 | 19.7 | 355 |
| 15 | 140 | 21.3 | 384 |
🧮 How to Calculate Estimated Average Glucose
To convert to mmol/L, divide the mg/dL result by 18.05.
❓ FAQs
What is a good A1c?
A good A1c is a value less than 5.7%. This corresponds to less than 117 mg/dL of eAG for non-diabetics. Consult your doctor if your A1c is higher.
How do I lower my blood sugar level?
- Exercise regularly
- Eat less sugar and more fiber
- Eat moderate portions
- Drink more water; avoid sugary drinks and alcohol
- Manage your stress
- Get adequate rest
What is my eAG for a 4.7% HbA1c?
eAG = (28.7 × 4.7) − 46.7 = 88.19 mg/dL. This means your blood sugar level is good and within normal range.
What is a dangerous level of A1c?
Dangerous levels of A1c are values higher than 9% for diabetic patients. For non-diabetics, values above 6.4% indicate diabetes and warrant medical attention.