My lowest-ever A1c result

Just got my lab results and lo and behold my A1c is 5.4. Doesn’t make sense as my meter average and my CGM average is at least 119. that doesn’t correlate to a 5.4 and besides, I’ve been getting A1c results for over 35 years. Usually they come out around 6.1, give or take. The previous one was 5.7. So…I Googled, and found this:

Average BG = 28.7 x A1c - 46.7

Using that formula, the A1c indicates my average bg is 108. I wish! :slight_smile: I’ve had this disease too many years to think that could be my average, even if you pretend my meters and CGM’s are inaccurate over the course of the last 2, or 3 months. I ran reports for various time ranges and didn’t get an average that came close to the A1c.

What I’m saying is I’ve had SO MANY A1c tests over the years, I think the lab made a bit of a boo-boo. (I’ve been diabetic since sometime prior to 1978, which was the year of my belated diagnosis)


There’s a correlation between average bg and A1c, but there’s actually quite a range for each A1c value. Not all study participants fall along the dotted regression line. You can see that in the graph below from a study in 2008 which developed the regression equation in your post.

My A1c is consistently about .5% below my estimated A1c- across quite a few different labs. At my last appointment, I asked my doctor to run some additional tests to make sure that I didn’t have any conditions that might be affecting the life of my red blood cells. Everything came back fine.

I suppose that makes me a “low glycator.” I’ll happily accept that! I do think it might be worthwhile to look at the % of time you’re spending above 160 or 180. See if that’s changed over the last few months. Try different values as well.

It may just be a lab error, but I don’t think the average actually paints the full picture. The average is not what is causing unhealthy glycation. The unhealthy glycation occurs because we’re spending too much time above a certain range (which I think varies from person to person).

Those are just my thoughts on the issue. I think it’s complicated.


Your post caused me to review my A1c history. I experienced one lower than the norm A1c that I think was really an outlier. Here is the sequence of every three months of A1c’s during that time.


These readings, circa 2009-2012, are listed in reverse chronological order. That 6.0% bracketed by the 6.8% three months prior and followed by a 6.6% reading suggests that the 6.0% was not real.

I say, relish and take credit for the low number. What I do think is real, however, is that there was movement toward a lower overall average during this period. The extent may not be be believable but the direction of change is more credible.


I have also over the years gotten a result that just didn’t match my numbers. I have asked for a redo and of course the next test was more in line with where I thought it should be. No lab is perfect, sorry to say. We always think they are right on, and they can be off just like our meters and CGMs.
So I guess you can just enjoy the result while you have it or if it is really bothering you, ask for another test. The last time this happen to me, I redid it and of course I got a higher number and was kicking myself for not just letting it ride!

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I definitely won’t take any credit for the 5.4 as holidays are always my downfall for high bg excursions due to the many goodies that I consume around Christmas time and Thanksgiving. Cookies galore! In fact one particular cookie my wife makes is so popular and so spectacularly good, that I convinced her for the first time, EVER, to make some more batches recently instead of the one-a-year batch. I took many of them to the P(ain) and T(orture) clinic. They loved them. My wife sent a box of them (they travel when when packed properly) to family. . Quite a delighted surprise for them as they don’t expect them except at Christmas. But I digress…the point being is that I’ve been “bad” over a longer period of time than usual for the holidays, yet my A1c somehow came out an all-time low. I agree it is an outlier.

oh yeah, out of the double batch she made, I got about a dozen for myself! Quite a deal!

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My endo would totally freak if I ever had a 5.4 A1C. She wants me somewhere between 6.1 and 6.5. As soon as I get a 6 or below she combs through my G5 CGM results for past 90 days and looks for the odd hypoglycemic event and lectures that I am burning brain cells. As much as I try to convince her that when I cruise along at 78-80 the CGM from time to time shows in the 40’s but when I finger stick during these low periods, I am always above 75. Or burying the transmitter in the mattress can also show a reading 25 points lower. From what I have read a lot of these bogus low CGM readings with G5 have been corrected with the G6 which will be available to Medicare recipients after April 2019. In the meantime, I will just keep nailing a 6.1 A1C every visit which is easy to do even with somewhat sloppy food management.

Has A1c outlived its usefulness? With CGM data measuring time in range, standard deviation, and your Glucose Variability Index, is much better info than A1c.

I get a A1C only to keep doctors and insurance happy

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The A1c is a measure of how much glucose is attaching to your red blood cells (glycation). Too much glycation has been associated with an increased risk of complications in many studies.

While I agree that time in range and glucose variability are good indicators of your control, A1c is still the best indicator of your risk of complications. As far as I know, the other factors have not yet been shown to be as statistically significant.


Or something else in your blood chemistry could be leading to a lower A1C reading… there are a lot of variables that can affect it. Eg anemia.

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I have had thousands of low readings during the past 60 yrs. My brain cells are doing just fine, as is the rest of my body. :grin:


Those measures provided by the cgm are great for the user and beneficial to management, but the A1C is the actual measure of how these things are ultimately effecting ones body… imo it will always be the gold standard

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The A1c is the only measure to be statistically validated to indicate the relative risk of developing secondary complications across a population. The conclusions about complication incidence at the individual level have not been demonstrated.

I believe that CGM data like time in range are much better feedback to use for daily management than the A1c. A high percentage of time in range, minimizing hypos, decreasing BG variability, and lowering the average BG will all contribute to a better A1c. These CGM statistics guide near term efforts while the A1c is a more general measure.

I have four primary goals for managing my glucose levels, the A1c is not one of those four.

I don’t find it useful for daily management but it has its value.

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By it’s very definition, an A1c value can’t be used to manage one’s DAILY glucose levels. That’s the province of meters and CGM’s, as you very well know. :slight_smile:

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Here’s a DiabetesMine column written by Mike Hoskins that examines the issue of the A1c versus other measures like time in range.

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7.7 ouch! That’s an average of 174. Not good. That’s the kind of numbers I used to get before I got better at managing the disease.

Not everyone can afford a CGM when insurance doesn’t cover.


Good article. Reflects a lot of my thoughts on A1c.

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I agree. However, my A1c heavily influences my D management goals. Right now, my A1c is the best it has ever been. Well into the non-D range.

However, if for some reason I became a high glycolator and my A1c went up 1.5%, then I would become much stricter in my diabetes management (setting new TIR, AG, and variability goals).

Time in range and glucose variability heavily impact my quality of life short-term. I’ve chosen ranges that make me comfortable and give me decent control. However, if my A1c were not in range, then I would create new goals of a tighter time in range and reducing my average and glucose variability. Doing this would require that I make sacrifices in my quality of life now so as to reduce my risk of developing long-term complications in the future.

I think both of these types of measurements are important. I agree with @Sam19 that the A1c is the gold standard when it comes to reducing the risk of complications.

This is true of almost every study.

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My a1c is consistently higher by 0.3 from my Dexcom data (estimated a1c).

There are different ways of calculating A1c. For instance, if you have one done, over the counter at the pharmacy, they might calculate it differently than your clinic typically does.