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HbA1c and estimated average glucose (ADAG)

Maps HbA1c to estimated average glucose over the past 2 to 3 months (and vice versa) using ADAG linear regression.

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Check the population, units and version. The result shows the formula or classification; it does not make an automatic treatment decision.

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Method · Limits of application

ADAG/Nathan 2008: eAG mg/dL 28.7 HbA1c−46.7; mmol/L 1.59 HbA1c−2.59

The ADAG 2008 regression was studied over three months in participants with relatively stable glycemia. Children, pregnant women and people with erythrocyte conditions were excluded; anemia, altered erythrocyte turnover and hemoglobinopathies may affect interpretation of HbA1c. Estimated average glucose is not a direct measurement, and the algebraic inverse is not an independent diagnostic test. The unit and coefficient variant must be preserved.

Conditions of use

Check the population, units, inclusion and exclusion criteria, and version in the original source. A result alone does not establish a diagnosis, discharge decision or prescription.

Documented parameters

HbA1c · %
or mean blood glucose (if HbA1c is not entered) · mg/dL

6/6 reference cases checked. Numerical tests are not clinical validation.

Sources and documentation

Documented formula

Transcribed from the source or a recorded revision; this is not a clinical recommendation.

Estimated average glucose (mg/dL) = 28.7 × HbA1c (%) − 46.7.

In mmol/L = 1.59 × HbA1c (%) − 2.59.

Inverse: HbA1c (%) = (average glucose + 46.7) ÷ 28.7.

References

Identifier: hba1c-glicemia-media-estimada

Original clinical content: Brazilian Portuguese.

Method version

ADAG/Nathan 2008: eAG mg/dL 28.7 HbA1c−46.7; mmol/L 1.59 HbA1c−2.59

hba1c-glicemia-media-estimada@native-2026-10-03+9692e1432b12

Source for the active edition

The bibliographic edition identifies the source. By itself, it proves neither full conformity of the formula nor clinical approval.

Synthetic cases checked (6)

Synthetic cases for checking the implementation, with no patient data.

Case 1

reference-001

Inputs

HbA1c: 7 %

{
  "hba1c": 7
}

Expected result

{
  "eag": 154.2
}

Actual result

{
  "a1c": 7,
  "eag": 154.2
}

Case 2

reference-002

Inputs

HbA1c: 6 %

{
  "hba1c": 6
}

Expected result

{
  "eag": 125.5
}

Actual result

{
  "a1c": 6,
  "eag": 125.49999999999999
}

Case 3

reference-003

Inputs

HbA1c: 5.7 %

{
  "hba1c": 5.7
}

Expected result

{
  "eag": 116.89
}

Actual result

{
  "a1c": 5.7,
  "eag": 116.89
}

Case 4

reference-004

Inputs

HbA1c: 5 %

{
  "hba1c": 5
}

Expected result

{
  "eag": 96.8
}

Actual result

{
  "a1c": 5,
  "eag": 96.8
}

Case 5

reference-005

Inputs

or mean blood glucose (if HbA1c is not entered): 154 mg/dL

{
  "gme": 154
}

Expected result

{
  "a1c": 6.993
}

Actual result

{
  "a1c": 6.993031358885017,
  "eag": 154
}

Case 6

reference-006

Inputs

{}

Expected result

{
  "error": true
}

Code and reproducibility

This tool’s code on GitHub

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Sources, version and reproduction instructions

The code tests are technical checks. Clinical approval and professional translation review are recorded separately.

Relationship with cancer research

General context — relationship to be defined

A resource for general clinical contexts. This edition does not assign a specific oncological relationship; selecting it for a study requires a justified question, population and purpose.