Does the reference range for the A1c vary from lab to lab?
What range does your lab use?
A few months ago, I posted a topic which involved many mentions of A1c’s. My A1c’s have run 6.0 to 6.5 recently, which I’ve thought were a little too high. My doctor thought they were too low.
For many years, the A1c reference range I worked with was 4.2 to 6.3. Thus making 6.5 a bit high. But not long ago my doctor/clinic shifted to Quest Diagnostics Labs, which I believe is a national chain in the U.S. I’ve just taken a hard look at their reference range, and they seem to be saying their range is 5.7 to 7.0. They call numbers under 7.0 for a known diabetic as ‘well controlled.’ That makes my 6.0-6.5 look entirely different.
Discussions of A1c’s I’ve read in this forum seem consistent with the lower range I’ve worked with for years. I believed the A1c test was standardized on a national basis? 5.7 to 7.0 seems a change.
So what ranges are being used out there?
FYI: Clinic’s Website says,
"For someone without known diabetes, a hemoglobin A1c value of 6.5% or greater indicates that they may have diabetes and this should be confirmed with a follow-up test.
For someone with known diabetes, a value <7% indicates that their diabetes is well controlled and a value greater than or equal to 7% indicates suboptimal control.
A1c targets should be individualized based on duration of diabetes, age, comorbid conditions, and other considerations. Currently, no consensus exists regarding use of hemoglobin A1c for diagnosis of diabetes for children."
Labs can really vary in ranges that are acceptable. Thyroid ranges I know hugely vary per each lab. And then doctors have their own ranges they want. I have wondered if the labs actually put down the ranges the doctors group that is ordering the tests wants.
Quest Diagnostics as well as their affiliates such as UltaLabs use certified equipment to measure A1C. Small clinics and doctor’s offices usually use non certified table top units and their A1C results for the same blood draw taken from the same patient, at the same time will vary by as much as 1% from a certified lab. An A1C of 7% or less is generally accepted as the highest % a patient can sustain long term without any complications, hence considered in control.
Regardless of the standards or ranges our labs use, many of us, especially here set our own standards, striving for our A1C, GMI, TIR etc to be as close to a normal non-diabetic’s values as possible. Regardless of what your doctor or lab considers as a good range, it is you, not the lab or doctor that has to live with the consequences of those numbers.
Forget about others and averages. Work on doing what is best for you in both the short term and long term.
The lab range doesn’t really matter in the case of this test.
It is a percentage of total hemaglobin. So at 6%, it means that 6% of your hemaglobin is glycated. Or glycosilated.
The reference ranges are only set as a guide for doctors who don’t know the tests very well, or for patients to get an idea of where they are.
The 7.0 limit is a diabetic range and 6.3 is a non diabetic range.
The value will be the same , but your value might fall out of the normal range depending on weather or not the lab knows that you are diabetic.
These days most people go with trying to stay in the normal range which is less than 6.3 % so it shouldn’t matter what the range is.
Doctors sometimes get worried when we are under 6.0 because to them it means we are having a lot of lows, however if you have cgm, your doc can actually see if you are running too low
My doctor wants me to shoot for 5.5 to 6.3, although I have been under 5.5 a few times, she has not given me a hard time about it as long as my dexcom data shows less than 2% of my data is in the low range.
It’s a big change from the 7.0 I had historically used my target.
My understanding is that there is a difference between ideal results and the reference range. Reference ranges are SUPPOSED to be be determined independently at each lab from “healthy” patient samples, to demonstrate what normal results look like coming from that specific lab equipment, in that specific environment, and with specific reagents. It’s showing real sample variance, not a hypothetical ideal set by the medical community. We’ve often repeated here how test results can vary greatly between labs, and this is exactly why each lab should have their own reference ranges.
That’s not always the case, though, nor is it always feasible for the lab to set their own reference ranges. In which case, they default to the reference ranges provided by the test manufacturer.
CP labs Reference Range is 4.2-5.6 %. I’m not sure what you are asking, as this is the range for non-diabetes.
This graphic conforms with my memory of the various labs and references that I’ve seen.
The National Glycohemoglobin Standardization Program, now known simply as NGSP, serves to standardize lab results across labs so that doctors and patients can make clinical decisions based on comparable results.
I find that my Quest results always run 0.2-0.4 below Dexcom Clarity “GMI”. And my Labcorp A1C results (before I changed insurance company) were always another 0.2-0.4 lower than that.
If you are tracking your A1C long-term, you will note that changing labs will often mean a change in the 0.2-0.5 range from your previous lab.
My lab’s (Quest) reference range is “<5.7%”. Full verbiage below.
Thanks to everyone for your help.
This is an old problem here. Many healthcare professionals are sure hypos kill. Sugars below 100 are ‘very dangerous’, sugars around 200 are ‘safe’. An HbA1c below 7 risks hypos, so one should strive for an HbA1c of around 7.
Yeah. That frightens the hell out of me for sure. My last doctor wanted me to increase my A1c to 7.5. Fortunately, she didn’t make it a demand. I heard one diabetic’s story whose doctor thought complications (like dialysis) were inevitable so there was no point in trying to prevent them. Some times doctors can be very scary.
Yes I hate to be against, but a doctor who graduated medical school in the past 10 years is going to be open to the new tech and ideas of the future, than an old one who learned diabetes when diabetes was a prolonged death sentence.