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Lab Tests/A1c test reference ranges


Dr. Prater, do you use Labcorp to run your blood tests? I ask, because for the A1c test from my Dr's office, who uses Labcorp, my reading was 5.3% and it lists the reference range for 'normal' as 4.0-6.0. But then it lists the borderline/pre-diabetes range as 5.5-6.4. First, everything I've seen from all the major diabetes organizations, like the ADA and others, say the A1c reference range for borderline diabetes is 5.7 to 6.4. But according to Labcorp, I'm only .2 away from being pre-diabetic instead of .4. I know it's a small amount, but why would they say 5.5 is the beginning of the borderline range when everyone else says it's 5.7? Second, if someone has a reading of 5.8. now could they be both in the normal range and the borderline range? I find that confusing, but mostly wonder about the 'pre-diabetic' range difference.  Thanks

I don't use Labcorp but they are a highly reputable lab. Lab reference ranges can vary slightly because the ranges are calculated from the average of what is run through the lab itself. So from year to year, the ranges can vary slightly from the same company even.

To answer the second question, a 5.8 for either lab would be listed as Normal because it's still within the clinical reference range, and also Pre-diabetic which is not a Clinical Diagnosis but an indicator that lifestyle and dietary changes should be made so that one does not cross into diabetes.

Hopefully this helped, and it is not the first time I've had someone question the way ranges are calculated and how they can differ from one lab to another, I don't think doctors do a good job of explaining that to their patients. More over, most doctors don't go by Functional lab ranges so even clinical ranges are not as adequate for assessing one's health as they could be.

Dr. Kalli Prater, D.C.  

Lab Tests

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Dr.Kalli Prater


I can answer questions about routine lab work, functional lab ranges for optimal health, what lab tests should be considered and when you need to seek a second opinion. I can also answer questions about specialty testing like: stool testing, hormone testing, and saliva testing.


I run lab tests in my office as a functional medicine practitioner and use functional lab ranges looking for patient's optimal health not their disease. I review many charts and labs and look at trends through the years as well as current symptoms. Usually I find more things on labs that the traditional doctor that correlate to the patient's concerns/issues.

American Chiropractic Association

Doctor of Chiropractic Medicine, B.S. in sports Medicine.

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