Every day brings us closer to a new way of communicating average blood sugar levels with patients. Thanks to work going on in Europe, a research team is collecting new data with the help of continuous glucose monitoring systems and comparing that data to people with type 1 and type 2 diabetes to come up with a new formula for the conversion. The research is not yet finished but I was able to glean new insight thanks to an article over at Diabetes Health:

“Using the previous nomenclature, the ADA had recommended that people with diabetes aim for an A1c of less than 7% and ideally below 6%. As best we can tell, it appears that using the new standards, a 7% A1c would be the equivalent of 155 mg/dl, and a value of 6% would be the equivalent of an average blood glucose value of 126 mg/dl.”

Keep in mind that the current translation of A1c to average blood glucose levels uses a formula derived during the landmark DCCT which I’ve blogged on previously.

The old way (the one that comes from a study that was already paid for and required no new research dollars and that we already use to report A1c and MBG to patients in our HomeCheck programs) indicates that a 6% A1c is equivalent to an average of 135 mg/dL while an A1c of 7% is equivalent to an average of 170 mg/dL. Here’s the ‘old’ conversion formula for figuring A1c to Mean Blood Glucose (MBG):

(% A1c x 35.6 - 77.3) = MBG mg/dl ( r ) of 0.82

REFERENCES: DCCT GROUP, NEW ENGL. J. MED: 329, 977-986 (1993) SANTIAGO, J.V., DIABETES, 42, 1549
1549-1554 (1993) DIABETES 1997; 46 (SUPPL 1): 8A, DIABETES CARE 1999; 22 (Suppl. 1): S32-41

If the new conversion formula holds, the mean difference we’re talking about here is calculated ‘thusly’:

[(135 - 126) + (170 - 155) / 2] / [(135 + 170)/2] = 12 / 152.5 = 7.9%

I’m not sure that the new formula vs the old formula matters that much. My point is, thanks to the newly funded research using the state of the art technology, we can be reassured that there is a direct correlation between A1c and average blood glucose levels as measured by electrochemical sensors (meters and cgms). I suppose there is a good argument for doing this even if it seems somewhat redundant.

The focus of this research and the forthcoming emphasis on ADAG vs. A1c (which will simply be an input to the formula) needs to be a realization that blood sugars in the currently acceptable targets of 7% A1c and its correlated ADAG of 155 mg/dL are completely unacceptable except in certain conditions of co-morbid conditions and/or to avoid severe hypoglycemia in some patients.

While the debate will rage for years whether or not it is beneficial to patients to use average blood sugar as represented by mg/dL vs. A1c we can only hope that the new research will publish final results ASAP and we can then get on to the business of communicating to patients why they should be striving for near normal (non-diabetic) glucose levels and why they should be demanding improved accuracy and precision from the diagnostic tests used to determine the true A1c, MBG and ADAG. Without an accurate A1c, the formula doesn’t matter or otherwise GIGO (garbage in garbage out).

ADAG or no ADAG, teaching patients advanced self-care skills via cause and effect via aggressive management programs is the key to a long and healthy life and that includes frequent checks on current blood glucose levels to avoid severe hypoglycemia and frequent A1c checks to determine recent average blood sugars.

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This entry was posted on Monday, October 1st, 2007 at 12:11 pm and is filed under A1c, Accuracy & Precision, Clinical. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.