BLOOD GLUCOSE TARGETS

For a discussion of glycohemoglobin (HbA1c) please refer to the Patient Information Section, “DIABETES MELLITUS” on this website. It’s important to remember that HbA1c measures average blood glucose (BG) over an approximately 120-day period. However, the more recent BG values contribute considerably more to the HbA1C result than the older values. This means that HbA1c is in fact a “weighted” average of BG levels. BG levels in the preceding 30 days contribute ~50% in the final result, BG levels in the preceding 31 to 90 days contribute ~40% in the final result, and BG levels in the preceding 91-120 days contribute ~10% in the final result. This explains why HbA1c can change relatively quickly with large changes in BG values. The general relationship between glycohemoglobin and BG levels is as follows:

HbA1c Ave BG* Range
4 65  
5 100 Non-diabetic
6 135  
6.5 150 ACE Target
7 170 ADA Target
8 205 Above Target
9 240  
10 275  
11 310  
12 345  


*These average blood glucose readings are plasma glucose. Mean whole blood glucose values are 10-15% lower. Most current blood glucose meters are calibrated to read as plasma glucose.



Typical blood glucose averages are as follows:

For a HbA1c of 6.0%:
Fasting Pre-Meal 1 ˝ hr Post-meal Bedtime
105 125 158 125


For a HbA1c of 6.5%:
Fasting Pre-Meal 1 ˝ hr Post-meal Bedtime
110 142 176 140


For a HbA1c of 7.0%:
Fasting Pre-Meal 1 ˝ hr Post-meal Bedtime
115 157 194 155



This data is extrapolated from the Diabetes Control and Complications Trial or DCCT (New Engl J Med 1993;329:977-986). This analysis of the DCCT glucose profile data is published (Diabetes Care 25:275-278, 2002).




Revised 9/08

 

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