Glucose A1C Conversion Calculator
Note: Enter one of the four values. The others will be calculated.
A1C (DCCT, %): —
A1C (IFCC, mmol/mol): —
Estimated Avg Glucose (mg/dL): —
Estimated Avg Glucose (mmol/L): —
References:
Nathan DM, Kuenen J, Borg R, et al. A1c-Derived Average Glucose Study Group.
Diabetes Care. 2008;31(8):1473-8.
This clinical decision support tool offers a quick means for converting average glucose readings into glycated hemoglobin A1C values. Glycemic goals are individualized and based on a patient’s duration of diabetes mellitus, medical comorbidities, psychosocial stressors and life expectancy.
A calculator for estimating  A1C based on average glucose
Enter the average glucose value in mg/dl. Review the estimated A1C in the output field
A calculator for estimating A1C based on average glucose
Enter the A1C value. Review estimated average glucose in the output field
Average glucose and A1C conversion chart (table)
| Blood sugar level (mg/dL) | Estimated A1C level |
| 97 | 5% |
| 126 | 6% |
| 154 | 7% |
| 183 | 8% |
| 212 | 9% |
| 240 | 10% |
| 269 | 11% |
| 298 | 12% |
| 326 | 13% |
| 355 | 14% |
What is Glycated hemoglobin A1C?
Glycated hemoglobin (hemoglobin A1C, HbA1c, glycated hemoglobin A1C, A1C, or glycohemoglobin) is a form of hemoglobin test that reflects the average plasma glucose concentration over the preceding two to three months. Glycated hemoglobin is formed in a non-enzymatic glycation pathway by the binding of glucose with the N-terminal valine residue on the β-chain of hemoglobin. The amount of glycated hemoglobin (HbA1c) in the blood provides information on average blood glucose control over time.
Advantages of A1C over other forms of glucose assessment.
A1C is a more accurate measure of blood sugar control than fasting blood glucose. The reason for this is that A1C measures the average amount of sugar over the past 2 to 3 months. This means it can pick up on fluctuations in your blood sugar that occur between meals and overnight, whereas fasting blood glucose only shows you how high your level was when you ate nothing at all.
A1C is also a better predictor of diabetes complications than fasting blood glucose. The higher your A1C level, the greater your risk of developing complications such as heart disease and kidney problems.
Overview of A1C as a Biomarker
A1C is recognized as the most reliable biomarker for assessing glycemic control over the preceding 2-3 months due to its strong correlation with predicting diabetes-related complications. Additionally, the American Diabetes Association recommends its use for diagnosing diabetes.
Biochemistry of A1C
Hemoglobin A1c is formed through the nonenzymatic attachment of glucose to the N-terminal valine of the beta chain of hemoglobin. Analytical methods rely on the charge and structural variations among hemoglobin molecules. However, hemoglobin variants (e.g., HbC, HbD, or sickle cell disease) may interfere with assays or affect erythrocyte lifespan, leading to inaccurate A1C levels. In such cases, alternative methods for monitoring glycemia should be used. The National Glycohemoglobin Standardization Program (NGSP) website provides detailed information on assay-specific interferences.
A1C Assay Methods
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HPLC (High-Performance Liquid Chromatography):This method separates glycated hemoglobin based on its lower isoelectric point. However, hemoglobinopathies (e.g., HbF) may cause interferences, which are often identifiable through chromatogram inspection.
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Boronate Affinity Methods:These detect glycation at multiple sites by binding glucose to m-aminophenylboronic acid. While minimally affected by hemoglobinopathies, these assays are less commonly available.
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Immunoassays:These use antibodies to target glucose and N-terminal amino acids, but may be impacted by structural hemoglobin changes, such as HbF. Advances are being made to reduce interferences.
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Enzymatic Methods:These break down hemoglobin to release glycated N-terminal valines, which are detected via chromogenic reactions. These assays are unaffected by hemoglobinopathies.
Standardization and Certification
The National Glycohemoglobin Standardization Program (NGSP) evaluates and certifies laboratory and home A1C tests, ensuring compliance with stringent accuracy standards. Advances in testing technology continue to enhance accuracy, supported by regulatory demands for improved performance.
Glycation Indices and Variability
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Glycation Gap (GG):The difference between measured A1C and predicted A1C based on serum fructosamine.
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Hemoglobin Glycation Index (HGI):The difference between measured A1C and predicted A1C based on mean blood glucose.
Both indices are stable within individuals and reflect a predisposition to glycation. High GG and HGI values may lead to falsely elevated A1C results and increased risk for microvascular complications. Whether these indices independently predict complications remains a subject of debate.
Limitations of A1C
Despite its widespread use, A1C has limitations:
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Delayed Response to Changes:A1C reflects average glycemia but does not capture short-term glucose fluctuations or recent clinical changes.
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Glycemic Variability:Acute glucose fluctuations may cause oxidative stress and endothelial dysfunction, which A1C does not measure. Continuous glucose monitoring or multiple daily tests provide better insights.
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Therapeutic Adjustments:A1C is not useful for fine-tuning insulin therapy.
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Conditions Affecting Accuracy:A1C results may be unreliable in conditions altering red blood cell lifespan, such as anemia or hemoglobinopathies.
