A1C not a reflection of glucose control

Thanks! I’ll check out the documentary. My A1Cs have always seemed to run low vs. m control, this has been going on for 10 years, so I don’t think it is about the lab.

Interesting, this seems to be a big question asked in an earlier thread I was reading: are complications caused by high blood sugar or glycation.

I just worry cause my average BG and standard deviation haven’t been great over the years, but I’ve always never worried about it because my A1Cs were generally in the 6.5-7.0 range which I felt was good enough.

Sounds like you’re doing fantastic. Congrats on having managed this disease for 50 years! The technology changes truly are awesome… especially Dexcom and Control IQ.

My question on age had nothing to do with blood glucose control – it was just trying to understand if the tendency to have A1C below your average blood glucose control was more common with younger people due to something specific to the hemoglobin test.

Sounds like for you this has been pretty consistently accurate though ever since you had the Clarity app.

Thanks for this link, super interesting.

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Yeah, I get the idea. I was just stating that my red blood cells, platelets, etc are all normal and those being higher or lower can throw an a1c number off. I am super fortunate to be pretty normal except for one part of my body not doing its thing correctly :slightly_frowning_face:


A month or two ago I went on a search spree, looking for studies on mortality, HbA1c, and Type 1 diabetes. Almost, or maybe even, all studies showed that moderate control, approximately centered around 6.4 was optimal. The exact bounds of that range varied, but both high and low A1c was correlated with higher risk of death.

Granted, there might be benefits from some newer tech, principally provided it translates into avoiding severe lows. In the past few years it started getting published that lows could be worse in terms of outcomes than persistent highs, or at least qualitatively different.

Also, as it relates to age and A1c, one of the older studies, not part of the recent collection I went through, even found an optimal level around 7, and in that old age was associated with better numbers.

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Sorry, I didn’t mean to glad this, it was an accident! I don’t know how to undo the flag or remove it!

What is glad? Flag? Anyway, not concerned. The moderator will look at it, understand it was a mistake…

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Oops, yes, FLAG! Another typo! Sorry!

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I am perplexed … not an unusual state for me!

Had my blood drawn a couple days ago. A1c result was 5.5 per the lab.

The A1c result per my purchased “at-home” Walgreen’s A1c test was 4.9 – and this home test I did on the same day as I had the blood drawn for the 5.5 labwork result.

My Dexcom CGM says my 90-day average BG is 96, and the “glucose management indicator” shows 5.6.

So things seem all over the place. Has anyone else seen such a disparity between a “home” A1c test and an “official” A1c test?

And the Dexcom thing drives me nuts. How can a GMI of 5.6 equate to my average BG of 96?

Any thoughts would be appreciated! Thanks.

So … which number is the correct one? I’m thinking the 5.5 from the lab A1c test. According to the test result, they show it would equate to 111 average BG. Again … all over the place.

Sounds to me like all your A1C’s are dead nuts on. There can be a .5% variation between labs depending on equipment used and if equipment is certified or not. I don’t think anybody cares, except you, about a difference between 4.9 and 5.6. It is sort of like highway speed limits. If you are in a 55mph zone, nobody is going to ticket you for doing 58mph. Your A1C numbers clearly indicate that you are under control and that is all that is important. Your doctor, most likely, wont even flinch until your A1C starts approaching 7%. Above 7 you are looking at possible long term complications so anything under 7% is considered in control at this time. I would not trust any home kits. Sounds like your A1C is in the 5.5%-5.6% range. Your Dexcom GMI at 5.6% looks correct too. I checked for periods when my Dexcom average BG was 96 and it also shows a GMI of 5.6.

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Thanks for your reply.

I hear and accept what you are saying. I guess I’m basically just disappointed. A BG of 96 equates to 5.0 or under when you check it on the A1c charts. So, between that and then the 4.9 on the Walgreen’s home test, I was hoping for a much lower number on that official lab A1c result.

Well, as they say, “onward,” I guess! I’ve had type 1 since 1971, and it’s always something!

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The charts and formulas used are based on a sampling of random diabetics and the problem with that is that there is really no such thing as an average diabetic. We are all different, some of us quite a bit different so between the variation in diabetics + the variations in testing equipment, there can be very significant A1C variations. Just stick with and make your decisions based on your Dexcom numbers and consider those accurate. What you are really looking for is not a number, but a trend. If your Dexcom GMI trend over time goes down, you are improving and if it goes up, you may want to take action. A1C is all about trends, not a specific number.


That’s a good way to look at it. Thanks.


I watch my Clarity time in range pretty close, I usually range between 85 to 90% weekly. Time in range has really helped me keep with the program. My A1C runs between 6.0 and 6.5 which is where my Doctor wants to see it and he quite concerned about lows, say <80.

Each doctor and each patient has their own comfort zone so the only thing that matters is that you and your doctor are on the same page. :grinning:

My 8yo son is only 15 months post diagnosis, but his lab A1c has come back higher (high sixes) than the Dexcom estimate (high fives to low sixes) each time so far.

That could be inaccurate from the lab, if it is a small lab with non-certified equipment or more likely I would guess due to your son’s BMI. I am very low BMI for an adult (19.5) and if I am not careful where I place my Dexcom sensor, readings can frequently come in low or just stop transmitting for several minutes causing an artificial low on Dexcom Clarity report.

For children, there is considerably more scatter in the relation between average bg and A1C, than there is for adults. See graph below from https://care.diabetesjournals.org/content/31/3/381