# Estimated Average Glucose (eAG) Calculator

Evaluates blood glucose levels linked to the HbA1c testing result.

You can read more about the formula used and the relationship between haemoglobin A1c and plasma glucose levels, in the text below the tool.

The estimated average glucose eAG calculator transforms the HbA1c test result in percentage to the eAG value in mg/dL or mmol/L which is closest to the average glucose (AG) value obtained through daily monitoring of blood glucose levels.

This is a method used for glycemic control and allows clinicians to set targets with which patients suffering from diabetes type 1 and 2 can compare their readings.

The original study involved 507 subjects, type 1 and 2 diabetic and non-diabetic.

Their average glucose levels were monitored for 3 months and at the end of a period HbA1c testing was done.

A linear regression equation model resulted from the two:

eAG = (28.7 x hemoglobin A1c) - 46.7

This is the transformation to be applied to the HbA1c results to transform it in eAG.

## Hemoglobin A1c

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Steps on how to print your input & results:

2. Then you can click on the Print button to open a PDF in a separate window with the inputs and results. You can further save the PDF or print it.

Please note that once you have closed the PDF you need to click on the Calculate button before you try opening it again, otherwise the input and/or results may not appear in the pdf.

## Algorithm

As a tool that evaluates blood glucose levels, this calculator accounts for the HbA1c testing and transforms the percentage provided by it in a target number that can easily be followed. This target number represents the desired glucose level in either mg/dL or mmol/L.

The formula used by the estimated average glucose eAG calculator is based on a linear regression equation model and is the following:

eAG = (28.7 x hemoglobin A1c) - 46.7

The transformation is not said to be impacted significantly by gender, age, type of diabetes or race, therefore there are no limitations of usage.

## eAG and HbA1c

The eAG is used as a target value that is set by the clinician as glycemic control and is often used in cases where the patient is not compliant to therapy, doesn’t check blood glucose often enough or keep track of self-monitoring.

HbA1c is an index of average glucose that can reveal evolution of blood glucose for weeks up to months. The method however is weighted, therefore, the preceding month weights more than the other three.

The term eAG was introduced by the American Diabetes Association (ADA), to facilitate translation of the A1c result to a value that is closer to the readings on glucose meters that patients are used to.

Glycosylated hemoglobin, HbA1c can change significantly with AG, as being showed by regular testing.

The following table introduces the translation of HbA1c in % to eAG in mg/dL and mmol/L:

 HbA1c (%) eAG (mg/dL) eAG (mmol/l) 5 97 5.4 6 126 7 7 154 8.6 8 183 10.2 9 212 11.8 10 240 13.4 11 269 14.9 12 298 16.5

HbA1c is considered to be the best overall glucose control test because it measures the glucose molecules attached to haemoglobin. The patient only has to compare the target eAG value set by the clinician after the A1c test with the blood glucose reading from the meter.

ADA recommends from 2 to 4 A1c tests per year. The results considered desirable is under 6% (meaning 6% of haemoglobin has glucose bound to it), which translated into an eAG of 126 mg/dL or 7 mmol/L.

## Blood glucose conversion

Blood sugar levels can be measured in either mg/dL or mmol/L. These are the conversion rules between the two:

■ mg/dL x 0.0555 = mmol/L

■ mmol/L x 18,0182 = mg/dL

The table consists of the most common values:

 mg/dl mmol/L mg/dl mmol/L 50 2.8 162 9 54 3 170 9.4 60 3.3 180 10 70 3.9 190 10.5 72 4 196 11 80 4.4 200 11.1 85 4.7 216 12 90 5 225 12.5 100 5.5 250 13.9 106 6 260 14.4 110 6.1 270 15 120 6.7 288 16 126 7 300 16.6 130 7.2 306 17 135 7.5 325 18 140 7.8 342 19 145 8 360 20 150 8.3 375 20.8 160 8.9 400 22.2

The original study was aimed at providing a mathematical relationship between A1c and average glucose levels.

The study consisted of 507 subjects (268 with type 1 diabetes, 159 with type 2 diabetes and 80 non-diabetic). AG levels were monitored constantly and at the end of a three-month period, A1c tests were performed.

Linear regression was used between the A1c and AG values obtained from the subjects and the tightest correlation was: AG(mg/dl) = 28.7 x A1C - 46.7, R(2) = 0.84, P < 0.0001 .

The study also emphasized that no significant differences were found because of patient variables such as age, gender, type of diabetes, ethnicity or smoking status.

David M. Nathan MD is director of the General Clinical Research Center and of Diabetes Center at Massachusetts General Hospital. Most of research focuses on therapies for type 1 and 2 diabetes and complication prevention. Browse Dr. Nathan’s publications on PubMed.

## Original source

Nathan DM, Kuenen J, Borg R, Zheng H, Schoenfeld D, Heine RJ; A1c-Derived Average Glucose Study Group. Translating the A1C assay into estimated average glucose values. Diabetes Care. 2008; 31(8):1473-8.

## Other references

1. Koenig RJ, Peterson CM, Jones RL, Saudek C, Lehrman M, Cerami A. Correlation of glucose regulation and hemoglobin AIc in diabetes mellitus. N Engl J Med. 1976; 295(8):417-20.

2. Kim HY, Lee SY, Suh S, Kim JH, Lee MK, Park HD. The relationship between estimated average glucose and fasting plasma glucose. Clin Chem Lab Med. 2013; 51(11):2195-200.

Specialty: Endocrinology

System: Endocrine

Objective: Determination

Type: Calculator

No. Of Variables: 1

Year Of Study: 2008

Abbreviation: eAG

Article By: Denise Nedea

Published On: March 16, 2017

Last Checked: March 16, 2017

Next Review: March 10, 2023