A1c to Glucose Converter
Converts HbA1c to estimated average glucose (eAG) and vice versa for diabetes management and patient education.
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ADAG Formula
eAG (mg/dL) = 28.7 × A1c - 46.7Based on the A1c-Derived Average Glucose (ADAG) study
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Estimated A1c
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About This Calculator
The A1c to Glucose Converter translates between HbA1c values and estimated average glucose (eAG) levels. This helps patients understand what their A1c means in terms of day-to-day blood sugar readings.
What is HbA1c? HbA1c (glycated hemoglobin) measures the percentage of hemoglobin that has glucose attached. Because red blood cells live about 90-120 days, A1c reflects average blood glucose over the past 2-3 months, with more recent weeks weighted more heavily.
The ADAG Formula: The conversion is based on the A1c-Derived Average Glucose (ADAG) study, which established: eAG (mg/dL) = 28.7 × A1c - 46.7 eAG (mmol/L) = 1.59 × A1c - 2.59
Clinical Use: • Help patients understand A1c in familiar glucose units • Set realistic glucose targets • Explain discrepancies between home glucose readings and A1c • Monitor diabetes management over time
Limitations: • Individual variation exists (some patients run higher/lower) • Conditions affecting red blood cell turnover affect accuracy • Does not capture glucose variability • Home glucose meters may differ from lab values
Formula
eAG (mg/dL) = 28.7 × A1c - 46.7The ADAG (A1c-Derived Average Glucose) study established the relationship: **A1c to Average Glucose:** eAG (mg/dL) = 28.7 × A1c - 46.7 eAG (mmol/L) = 1.59 × A1c - 2.59 **Average Glucose to A1c:** A1c = (eAG + 46.7) / 28.7 A1c = (eAG + 2.59) / 1.59 (if glucose in mmol/L) **Reference Table:** A1c 5% → 97 mg/dL (5.4 mmol/L) A1c 6% → 126 mg/dL (7.0 mmol/L) A1c 7% → 154 mg/dL (8.6 mmol/L) A1c 8% → 183 mg/dL (10.2 mmol/L) A1c 9% → 212 mg/dL (11.8 mmol/L) A1c 10% → 240 mg/dL (13.4 mmol/L)
Clinical Considerations
- •A1c may be inaccurate in conditions affecting red blood cell turnover
- •Hemoglobinopathies can affect A1c measurement (method-dependent)
- •eAG is an estimate - individual variation of ±15-20% is common
- •Does not capture glucose variability or time in range
- •Target A1c should be individualized (not always <7%)
Limitations
- •Conditions that shorten RBC lifespan lower A1c (hemolysis, bleeding, transfusions)
- •Conditions that lengthen RBC lifespan raise A1c (iron/B12 deficiency, splenectomy)
- •Pregnancy, chronic kidney disease, and liver disease affect interpretation
- •Some A1c assays are affected by hemoglobin variants
- •Does not reflect glycemic variability
Interpretation Guide
| Range | Classification | Recommendation |
|---|---|---|
| <-5.7 | Normal | Normal A1c. Continue healthy lifestyle. Rescreen based on risk factors. |
| 5.7-6.5 | Prediabetes | Prediabetes range. Lifestyle modification recommended (diet, exercise, weight loss). Consider metformin for high-risk patients. |
| 6.5-8 | Diabetes - At Target | Diabetes range. A1c <7% is target for most non-pregnant adults. Individualize target based on age, comorbidities, hypoglycemia risk. |
| 8-20 | Diabetes - Above Target | Above target for most patients. Intensify therapy. Address medication adherence, diet, and barriers to control. Consider specialist referral. |
Frequently Asked Questions
What is a normal A1c?
A normal A1c is below 5.7%. Prediabetes is 5.7-6.4%, and diabetes is diagnosed at 6.5% or higher. For most adults with diabetes, a target of <7% is recommended, but this should be individualized.
Why doesn't my A1c match my home glucose readings?
A1c reflects average glucose over 2-3 months, including overnight and post-meal values you may not capture. Home readings may be biased toward certain times of day. Additionally, there's natural individual variation in the A1c-glucose relationship.
How often should A1c be checked?
For patients meeting treatment goals with stable glycemic control, test A1c at least twice per year. For patients not at goal or with therapy changes, test quarterly. Certain situations (hemoglobinopathies, altered RBC turnover) may require alternative monitoring.
What conditions make A1c unreliable?
Conditions that shorten red blood cell life (hemolytic anemia, recent transfusion, bleeding) falsely lower A1c. Conditions that prolong RBC life (iron deficiency, B12 deficiency) falsely raise A1c. Some hemoglobin variants interfere with certain A1c assays.
What A1c target should I aim for?
The ADA recommends <7% for most non-pregnant adults with diabetes. Less stringent targets (7.5-8%) may be appropriate for those with limited life expectancy, extensive comorbidities, or high hypoglycemia risk. More stringent targets (<6.5%) may be appropriate for some if achievable without significant hypoglycemia.
References
1. Nathan DM, Kuenen J, Borg R, et al.. Translating the A1C assay into estimated average glucose values. Diabetes Care. 2008. doi: 10.2337/dc08-0545
View Source →2. American Diabetes Association Professional Practice Committee. Standards of Medical Care in Diabetes—2024. Diabetes Care. 2024. doi: 10.2337/dc24-SINT
View Source →3. American Diabetes Association. Glycemic Targets: Standards of Medical Care in Diabetes. Diabetes Care. 2024
Last updated: 2025-01-15
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