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Calculate your estimated average glucose (eAG) from A1C percentage
Normal: <5.7% | Pre-diabetic: 5.7-6.4% | Diabetic: ≥6.5%
| A1C (%) | eAG (mg/dL) | eAG (mmol/L) | Category |
|---|---|---|---|
| 4.0 | 68 | 3.8 | Normal |
| 4.5 | 82 | 4.6 | Normal |
| 5.0 | 97 | 5.4 | Normal |
| 5.5 | 111 | 6.2 | Normal |
| 5.7 | 117 | 6.5 | Pre-diabetic |
| 6.0 | 126 | 7.0 | Pre-diabetic |
| 6.5 | 140 | 7.8 | Diabetic |
| 7.0 | 154 | 8.6 | Diabetic |
| 7.5 | 169 | 9.4 | Diabetic |
| 8.0 | 183 | 10.2 | Diabetic |
| 8.5 | 197 | 10.9 | Diabetic |
| 9.0 | 212 | 11.8 | Diabetic |
| 9.5 | 226 | 12.6 | Diabetic |
| 10.0 | 240 | 13.4 | Diabetic |
Estimated Average Glucose (eAG) translates your A1C percentage into the same units (mg/dL or mmol/L) that you see on your daily glucose meter readings. This makes it easier to understand what your A1C means in practical terms. While A1C is expressed as a percentage of glycated hemoglobin, eAG represents the average of all your glucose levels over the past 2-3 months, including fasting readings, pre-meal readings, post-meal readings, and overnight levels.
The eAG concept was introduced following the ADAG (A1C-Derived Average Glucose) study, which used continuous glucose monitoring and frequent finger-stick measurements to establish the mathematical relationship between A1C and average glucose levels. The formula eAG (mg/dL) = (28.7 × A1C) - 46.7 emerged from this research. For example, an A1C of 6% corresponds to an eAG of about 126 mg/dL (7.0 mmol/L). It's important to understand that eAG is an average - your individual readings will vary above and below this number throughout the day. Some people with well-controlled diabetes might have readings that stay close to their eAG, while others might have significant fluctuations with the same A1C. The eAG helps bridge the gap between laboratory results and daily glucose monitoring, making diabetes management more intuitive.
The relationship between A1C and estimated average glucose is based on the ADAG study's findings. To calculate eAG from A1C, use the formula: eAG (mg/dL) = (28.7 × A1C) - 46.7. The number 28.7 is the slope of the relationship (how much eAG changes for each 1% change in A1C), and 46.7 is the y-intercept (the correction factor). For example, if your A1C is 7.0%, your eAG would be (28.7 × 7.0) - 46.7 = 154 mg/dL. To convert to mmol/L, divide by 18.0182, giving 8.6 mmol/L.
It's crucial to understand that eAG is a mathematical average and doesn't indicate the range or variability of your glucose levels. Two people could have the same A1C and eAG but very different glucose patterns. One might have stable readings close to their eAG throughout the day, while another might swing between very low and very high readings that average out to the same number. This is why both A1C testing (for long-term average) and regular glucose monitoring (for daily patterns) are important for comprehensive diabetes management.
The eAG represents a weighted average that gives more importance to recent glucose levels (the past 30 days) than older levels (2-3 months ago), because red blood cells are constantly being replaced. Approximately 50% of the A1C value reflects glucose levels from the previous month, 25% from the month before that, and 25% from the third month. If you've recently made changes to your diet, exercise, or medications, you might see improvements in your daily readings before they fully reflect in your A1C. Conversely, if you've had a particularly good or bad month, it will significantly impact your next A1C test result.
Your eAG represents the mathematical average of all glucose readings over 2-3 months. If your eAG is 154 mg/dL, this means that if you had been testing your glucose many times per day (including overnight), the average of all those readings would be approximately 154 mg/dL.
eAG doesn't reveal glucose variability. You could have very stable readings (e.g., 140-170 mg/dL) or wild swings (e.g., 50-300 mg/dL) and have the same eAG. Time in range, glucose variability, and patterns are equally important for diabetes management.
Compare your eAG to your average self-monitored glucose readings. If they're similar, your self-monitoring captures your overall patterns well. If your self-monitored average is lower than your eAG, you might be missing high readings (post-meal spikes or overnight highs).
This calculator provides estimates based on the ADAG study formula. Individual glucose patterns may vary. Always use laboratory A1C tests for diagnosis and monitoring, and consult your healthcare provider for personalized diabetes management goals and interpretation of results.
Several reasons: You may not be testing at all times of day (missing overnight or post-meal highs), your testing frequency may have changed recently, or there's individual variation in how glucose attaches to hemoglobin. If the difference is large, discuss testing patterns with your healthcare provider.
They should be similar but may not match exactly. Your meter average depends on when and how often you test. If you only test fasting, your meter average will be lower than eAG (which includes all times). Continuous glucose monitors provide averages closer to eAG since they measure constantly.
No, eAG is just an average. Two people with the same eAG could have very different glucose patterns - one with stable levels and one with wild swings. This is why metrics like time in range, coefficient of variation, and standard deviation from CGM data are also important for comprehensive diabetes management.
Since eAG is derived from A1C, which reflects 2-3 months of glucose control, eAG changes gradually. Improvements in glucose management will show in daily readings before impacting eAG. About 50% of the value comes from the past month, so recent changes have more impact than older ones.
This varies by individual. For people without diabetes, eAG is typically under 117 mg/dL (6.5 mmol/L). For those with diabetes, the American Diabetes Association generally recommends A1C under 7% (eAG ~154 mg/dL), but targets should be individualized based on age, complications, and other factors.
The eAG calculation itself is straightforward math, but medications that affect red blood cell turnover can affect A1C accuracy (and thus eAG). These include iron supplements (treating anemia), EPO injections, and medications affecting kidney function. Discuss with your healthcare provider if you're on such medications.
Both are useful. A1C is the standard for diagnosis and medical records. eAG helps you relate A1C to your familiar daily glucose units. Use whichever helps you better understand your diabetes control. Many healthcare providers now report both values on lab results.
The formula eAG = (28.7 × A1C) - 46.7 is the same for everyone, but individual variation exists in how closely someone's actual average glucose matches their eAG. The formula represents population averages from the ADAG study. Most people fall close to this line, but some may vary by 10-20 mg/dL.
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