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Confused by HbA1c

Mbaker

Mbaker

Well-Known Member
Messages
4,340
Location
Essex
Type of diabetes
Treatment type
Diet only
Dislikes
Available fast foods in Supermarkets
Maybe something is slightly weird with me as I have low fbg (4.2 over 90 days) and after meal average of 5.0, and a general combined average of 4.4 on my One Touch Select Plus. On 28th December I had a measured 4.4 fbg which was identical to my Diabetic Nurses NHS synchronised meter using the same blood sample - yet my HbA1c was 5.5% ?

I don't get it, when I measure at random times my readings are mainly below the A1c, so for example today 3.7 mmol fbg @ 07.55, pre dinner @ 17.42 3.7 mmol, 22.10 4.6 mmol - all on One Touch Select Plus. I tested on Acc-Chek Mobile at 22.10 which was a 4.8 mmol and on Freestyle Optium Neo (72 mdg, accidentally purchased an American unit) 4.0 mmol. Do you know why I can measure quite low for most of the majority of the day and have a higher than expected A1c, when I measure at random I am not getting massive spikes, so most prandials under 6 and not for a great length of time (certainly no where near my averages). I have checked that my diet does not have any known fructose and don't have a thyroid problem. My white cell count is not "normal", but is normal for me as checked at my surgery several times, could this impact HbA1c.

I generally eat on a 2 meal a day protocol eggs, bacon (sometimes sausage), mushrooms, tomatoes or mixed nus (quite a lot), berries, sometimes full fat Greek yogurt. For dinner always LCHF meat / fish, lots of above ground veg, maybe some more nuts and dark chocolate or avocado. On OMAD a similar LCHF based meal (lots of variety, e.g. curries, oxtail etc), for desert the nuts and berries / 100% dark chocolate. Oh forgot I drink some Apple Cider Vinegar before most meals and have on the side a spoon full of mixed seeds. I drink hot freshly squeezed, lemon / lime, black tea, herbal teas, fresh brew coffee. I have no sweetners. Any ideas would be welcome. I have moved to OMAD for most of the week now (at least 5 days), I have tested so many times now I know I have good averages for the majority of the day, so will see what my next HbA1c is, but would like to understand my current position.
 
I got a result just before xmas that didn't make sense based on the numbers I was reading. My assumption was that I just wasn't reading spikes after eating and basically I gave up at that point, if that's not enough effort what is.
 
Hi @Mbaker

I’m tagging @Bluetit1802 as I believe she has the same issue and it’s to do with the life of the red blood cells.

I had a similar issue - my last HbA1c was 5.3%, which while very good, equates to a higher BG level than I was seeing from my own testing.

I think it goes to show the importance of doing your own testing.
 
How often are you testing as unless you are testing every day upon waking, before meals and 2 hours afterwards every day your meter's average may not be correct. There is also the margin of error that is present in meters and sometimes different fingers or different batches of test strips can vary readings as well.
 
Hi,

I have exactly the same problem as yourself @Mbaker

The problem doesn't lie with white blood cells at all, it lies with red blood cells as that is where the glucose is carried (haemoglobin). The HbA1c measurement is based on the average life span of red blood cells, which is approximately 120 days. As we are all aware, not everyone is average. If our RBC live longer than 120 days our HbA1c will be higher than other tests indicate. If they live less than 120 days the HbA1c will be lower than other tests indicate. If there are abnormalities in our RBC the HbA1c can be skewed. There are other factors that affect it.

I no longer take any notice of my HbA1c other than watching for trends. I rely on my finger pricking and an occasional Libre sensor for a more realistic measurement of my blood glucose levels.

https://pbs.twimg.com/media/DG4FKXNUQAA2rMo.jpg
https://chriskresser.com/why-hemoglobin-a1c-is-not-a-reliable-marker/
http://www.pathology.leedsth.nhs.uk/pathology/Portals/0/PDFs/BP-2013-01 Diabetes.pdf
https://www.diabetes.co.uk/forum/th...due-to-red-blood-cell-age-variability.110793/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2581997/
http://www.ngsp.org/factors.asp

My haematocrit levels are always right at the top of "normal", teetering on being elevated and about to fall over the line. As this is one thing that can affect HbA1c levels, I believe in my case this is the reason.
 
JohnEGreen said:
Ooher just realized that my RBC count was low on my last test so my HbA1c test would have been unreliable had not occurred to me to check till @Bluetit1802 mentioned RBC and haematocrit levels.
Click to expand...

Was your HbA1c a lot lower than your other tests indicated?

Whilst I was researching reasons for skewed HbA1c tests I came across a blog about haematocrit levels and blood glucose. It concludes:

So I recommend that you check your hematocrit levels (which should be part of your periodic panel of blood tests) and if they are on the high side then check to see whether the accuracy of your metering system might be affected. If so, consider shifting to a different system offering less sensitivity to hematocrit.

https://www.diabetesdaily.com/forum/testing-blood-sugar/83550-measuring-glucose-high-hematocrit/

I immediately checked my Accu Chek Mobile and found this in the specs.

Influence of hematocrit
The influence of hematocrit level on the results was
investigated with native capillary blood samples of
254 patients. Hematocrit levels were available in the range
from 24% to 53%.
The result (deviation Accu-Chek Mobile
system to the laboratory method Hexokinase, IFCC
plasma) is shown in Figure 12.
In an additional laboratory experiment the hematocrit of
venous blood samples was manipulated artificially to cover
the range from 0% (plasma) to 65%.
Both experiments prove that clinically correct results are
produced in a hematocrit range from 25 % to 55 %

As my haematocrits hover at 45% (Female standard max is 46%) I feel confident my meter is accurate in as far as haematocrits are concerned, but am not confident the HbA1c is quite so accommodating.
 
I must admit HbA1c of 35 was somewhat lower than I had anticipated compared to averages but just reviewing my results I found that my haematocrit level was actually dead on the lower reference level at 4.00 though my RBC count was quite a bit lower than the lower reference level so would be counted as anemic, thus skewing my HbA1c I would think.
 
JohnEGreen said:
I must admit HbA1c of 35 was somewhat lower than I had anticipated compared to averages but just reviewing my results I found that my haematocrit level was actually dead on the lower reference level at 4.00 though my RBC count was quite a bit lower than the lower reference level so would be counted as anemic, thus skewing my HbA1c I would think.
Click to expand...

Yes, it is looking like your HbA1c may have been artificially low, but it keeps your nurse and doctor happy, so why worry as long as you are aware of it. ;)
 
4ratbags said:
How often are you testing as unless you are testing every day upon waking, before meals and 2 hours afterwards every day your meter's average may not be correct. There is also the margin of error that is present in meters and sometimes different fingers or different batches of test strips can vary readings as well.
Click to expand...
Thank you all for the responses, being an IT guy (always getting in the way, like all day today, but can't complain really) I am only just getting back to this thread. So thank you ladies and gents; I don't know about others but as a techy type I have a built in must know nature.

As another example fbg this morning 3.9 mmol, had pub lunch with my business partner and client at 13.00 (salmon, broadbeans, salad (contra band of my nut mix, circa 100 grams and seeds), bgs reading just now (16.28) 5.0 mmol; I will have nothing further to eat today and will measure again and post later.
 
Last edited:
I would probably not worry too much about your absolute A1c number as you are well into the normal level with great control, as assessed by your meter monitoring. I am also pretty sure the tables showing how blood sugar levels compare to HbA1c are only indicative. And based on averages!

I agree with @Bluetit1802 that your trend is the thing to watch, to make sure it isn’t creeping up. This is what I focus on...
 
Just got to my Hotel. Blood sugars 3.9 mmol on One Touch Select Plus, 4.1 mmol on Accu Chek Mobile, 62 (3.4 mmol) Freestyle Neo.
 
Bluetit1802 said:
Hi,

I have exactly the same problem as yourself @Mbaker

The problem doesn't lie with white blood cells at all, it lies with red blood cells as that is where the glucose is carried (haemoglobin). The HbA1c measurement is based on the average life span of red blood cells, which is approximately 120 days. As we are all aware, not everyone is average. If our RBC live longer than 120 days our HbA1c will be higher than other tests indicate. If they live less than 120 days the HbA1c will be lower than other tests indicate. If there are abnormalities in our RBC the HbA1c can be skewed. There are other factors that affect it.

I no longer take any notice of my HbA1c other than watching for trends. I rely on my finger pricking and an occasional Libre sensor for a more realistic measurement of my blood glucose levels.

https://pbs.twimg.com/media/DG4FKXNUQAA2rMo.jpg
https://chriskresser.com/why-hemoglobin-a1c-is-not-a-reliable-marker/
http://www.pathology.leedsth.nhs.uk/pathology/Portals/0/PDFs/BP-2013-01 Diabetes.pdf
https://www.diabetes.co.uk/forum/th...due-to-red-blood-cell-age-variability.110793/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2581997/
http://www.ngsp.org/factors.asp

My haematocrit levels are always right at the top of "normal", teetering on being elevated and about to fall over the line. As this is one thing that can affect HbA1c levels, I believe in my case this is the reason.
Click to expand...

I think I've read the same things you have on A1c levels. I've also learned to not pay attention at all to them and focus on daily finger pricking results. Keeping those in the right range is more important to me and just make A1c levels irrelevant in my opinion, at least in my case.
 
Mbaker said:
Just got to my Hotel. Blood sugars 3.9 mmol on One Touch Select Plus, 4.1 mmol on Accu Chek Mobile, 62 (3.4 mmol) Freestyle Neo.
Click to expand...
That's interesting, does the Freestyle Neo typically under read? As a T1, I'd be having to treat for a hypo at that reading and unnecessary glucose is really bad for my control....
 
EllieM said:
That's interesting, does the Freestyle Neo typically under read? As a T1, I'd be having to treat for a hypo at that reading and unnecessary glucose is really bad for my control....
Click to expand...
For me it us always less than the Accu-Accu-Chek and One Touch. It appears whatever algorithm Freestyle products use don't work for me.
 
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