An average blood glucose level, expressed in milligrams per deciliter (mg/dl), based on a person’s glycosylated hemoglobin (HbA1c) level. Estimated average glucose (eAG) is considered easier for people with diabetes and their doctors to work with than HbA1c, since it is given in the same units as everyday blood glucose readings.
The HbA1c test is currently considered the best measure of overall blood glucose control and of the risk of developing diabetic complications in the future. The test measures the percentage of hemoglobin molecules in the blood that have glucose attached to them. People without diabetes typically have an HbA1c level under 6%, and the American Diabetes Association recommends that people with diabetes strive for an HbA1c level below 7% (below 6% in certain individuals).
In a study recently published in the journal Diabetes Care, researchers sought to define the relationship between HbA1c and average blood glucose level. Over a period of three months, they recorded continuous glucose monitor readings and seven-times-daily blood glucose meter readings in 268 people with Type 1 diabetes, 159 with Type 2 diabetes, and 80 without diabetes. The researchers compared these data with the HbA1c levels of the participants at the end of the three-month period. Based on the relationship between the two, they designed a mathematical formula for translating HbA1c into eAG.
Someday, eAG may be printed alongside HbA1c in laboratory reports. Until then, there are a few ways to calculate eAG yourself: You can log on to the American Diabetes Association’s Web site at www.diabetes.org/ag, where you’ll find a conversion calculator as well as a chart showing equivalent values of HbA1c and eAG.
You can also use the formula directly, using a calculator: 28.7 x HbA1c — 46.7 = eAG (in mg/dl). For example, an HbA1c level of 7% would translate into 28.7 x 7 — 46.7, or roughly 154 mg/dl.
To read more about the HbA1c test, go to www.diabetesselfmanagement.com/2/A1c.