HbA1c and Estimated Average Glucose (eAG)

Source of this information: ADA and http://www.ngsp.org/A1ceAG.asp


There is a very predictable relationship between HbA1c and AG. 
Understanding this relationship can help patients with diabetes and their health-care providers set day-to-day targets for AG based on HbA1c goals
Fasting glucose should be used with caution as a surrogate measure of AG. 
Finally, it is important to remember that HbA1c is a weighted average of glucose levels during the preceding 4 months. Unless the patient’s glucose levels are very stable month after month, quarterly measurement is needed to insure that a patient's glycemic control remains within the target range. 

How does HbA1c relate to average glucose (AG)?

In the Diabetes Control and Complications Trial or DCCT (New Engl J Med 1993;329:977-986) study of patients with Type 1 diabetes, quarterly HbA1c determinations were the principal measure of glycemic control; study subjects also performed quarterly 24-hour, 7-point capillary-blood glucose profiles. 

Blood specimens were obtained by subjects in the home setting, pre-meal, 90 minutes post-meal, and at bed-time. In an analysis of the DCCT glucose profile data (Diabetes Care 25:275-278, 2002), mean HbA1c and AG were calculated for each study subject (n= 1439). Results showed a linear relationship between HbA1c and AG 

(AG(mg/dL) = ( 35.6 x HbA1c ) - 77.3), with a Pearson correlation coefficient (r) of 0.82.

CALCULATOR: The following link will help to do the Estimated Average Glucose Calculation

http://professional.diabetes.org/GlucoseCalculator.aspx :

HbA1c (%)	eAG (mg/dL)	eAG (mmol/l)
5	97	5.4
6	126	7.0
7	154	8.6
8	183	10.2
9	212	11.8
10	240	13.4
11	269	14.9
12	298	16.5