Anomalous HbA1c Results

Dee_UK

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I had an over 40 health check in Feb and was told I had high cholesterol. This was a shock because I have a BMI of 20.5, do regular cardio exercise and believe I follow a good diet. I therefore opted for a venous blood test, which also included HbA1c and was told my cholesterol was actually fine but that I had an HbA1c of 43, making me pre-diabetic.

This was also a shock so I decided to seek a 2nd opinion from a private GP a week later and got a result of 35! My local GP suggested a repeat test, which I had 6 weeks ago, but that came out even higher than the first one at 44!

The private GP then suggested sending identical samples taken from the same blood draw to both laboratories and his lab came back with 34 and the NHS lab 37, which are statistically not significantly different, but neither Doctor can explain the previous results, as I understand HbA1c can't fluctuate from 43 to 35 in one week and then from 44 to 34 or even 37 in the space of 6 weeks.

I'm wondering how common it is for HbA1c readings to be so inconsistent and if others have been given results that surprised them, but may not have been detected as anomalous because the repeat test was done by the same lab?

I'm guessing I'm fairly unusual in that I chose to have two samples analysed by two different labs within such a short timescale, so worry I could be the tip of the iceberg of patients being given unknowingly inaccurate results?

Has anyone else had a similar experience?
 

AndBreathe

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I had an over 40 health check in Feb and was told I had high cholesterol. This was a shock because I have a BMI of 20.5, do regular cardio exercise and believe I follow a good diet. I therefore opted for a venous blood test, which also included HbA1c and was told my cholesterol was actually fine but that I had an HbA1c of 43, making me pre-diabetic.

This was also a shock so I decided to seek a 2nd opinion from a private GP a week later and got a result of 35! My local GP suggested a repeat test, which I had 6 weeks ago, but that came out even higher than the first one at 44!

The private GP then suggested sending identical samples taken from the same blood draw to both laboratories and his lab came back with 34 and the NHS lab 37, which are statistically not significantly different, but neither Doctor can explain the previous results, as I understand HbA1c can't fluctuate from 43 to 35 in one week and then from 44 to 34 or even 37 in the space of 6 weeks.

I'm wondering how common it is for HbA1c readings to be so inconsistent and if others have been given results that surprised them, but may not have been detected as anomalous because the repeat test was done by the same lab?

I'm guessing I'm fairly unusual in that I chose to have two samples analysed by two different labs within such a short timescale, so worry I could be the tip of the iceberg of patients being given unknowingly inaccurate results?

Has anyone else had a similar experience?

Dee, there can be differences in lab results, but not usually by much. Most of those are due to rounding up or down to return a result. So, 35.6 would be 36, but 35.4 would be 34. Quite a bit can change in 6 weeks. HbA1c tests notionally represent your average blood sugars over a 3 month period, but it is heavily weighted to the most recent 2 weeks.

Some switched on GPs retest HbA1cs after 6-8 weeks post diagnosis, because someone with T2 newly paying strict attention to their diet can impact heir numbers significantly, so a 6-8 week retest can be pretty motivational.

Do you have any other issues - I'm thinking any blood disorders or dehydration issues?
 
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Dee_UK

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Thank you that's very helpful. The only thing I changed since the original test was to cut out my 1 teaspoon in tea but I only ever had 1 cup per day, so I don't think that would make that much difference?

No, I don't have any other issues AFAIK but the local GP has booked me in for a CT of my Pancreas next week to rule out any medical causes seeing as my diet doesn't seem to be an obvious issue.
 

Melgar

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I had a low BMI and it's gone down even further to 19, very fit, ate a Mediterranean diet prior to my initial diagnosis, no type 2 diabetes in my family, no insulin resistance and insulin sensitive. Low Triglycerides. I had those pancreas tests to see if there is anything going on, but everything was fine. The only result was lowish C-Peptides. Lab results can fluctuate depending on the lab, odd that there is such a wide range of result though. It's very frustrating. You may wish to go low carb to see if reducing your carb intake down drops your Ac1's. It didn't make any difference to mine, but everyone is different. Ed for errors.
 
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Dee_UK

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I had a low BMI and it's gone down even further to 19, very fit, ate a Mediterranean diet prior to my initial diagnosis, no type 2 diabetes in my family, no insulin resistance and insulin sensitive. Low Triglycerides. I had those pancreas tests to see if there is anything going on, but everything was fine. The only result was lowish C-Peptides. Lab results can fluctuate depending on the lab, odd that there is such a wide range of result though. It's very frustrating. You may wish to go low carb to see if reducing your carb intake down drops your Ac1's. It didn't make any difference to mine, but everyone is different. Ed for errors.
That's interesting. Thanks Melgar. I also had a full blood workup and everything was normal except slightly elevated ferritin, but I think that was because I'm on a contraceptive pill that means I don't bleed so probably have higher iron than is considered "normal" for women my age who tend to be iron deficient. My Triglycerides level was 0.4-0.6 (across the 3 tests), which I believe is within the normal range of 0-1.6.

My carb intake is already pretty low. I've used My Fitness Pal since 2016 (for maintenance rather than targeted weight loss) and I'm always under the 50% target for carbs and average about 40%. I'm also always up on Protein (23% vs. target of 20%), so I was really at a loss when the Diabetes Nurse asked me "what we're going to do about it."

If you don't mind me asking, were you diagnosed with T2D on the basis of your HbA1c? If so, did you get a 2nd opinion? I'm just curious as to how reliable the tests are given my experience and what they expect you to do if you already have a good diet?
 
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Melgar

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Yes, I was diagnosed from my HbAc1 results, I did get them down to prediabetic levels on a very low carb diet, but to be honest I was expecting my new HbAc1 results to be in the low 5’s but they were 6.3. Not high I know, but still in a range that can damage your vascular system in the long term. That was 9 months of low carbing for little in return. So I figured there is something else going on. As in keeping with most people who go on a low carb diet, my Ac1 results should have been a lot lower. One may suggest I was not in nutritional ketosis but I was. I‘m at a loss. My Trigs were 0.6. I don’t share any of the classic type 2 features other than my age of onset. Someone remarked on one of the forums here that type 2 is nothing short of a dumping ground for anything that is not autoimmune, it does seem that way. In short it doesnt help people who don’t fit the classic type 2 profile. We are left high and dry. I have bent too many ears on here and with my diabetic team about my own situation because it’s like shouting into the wind. There are no answers at the moment. Now saying all that about my situation doesn’t mean going low carb will not work for you. Everyone is different and it is certainly worth giving very low carb A go. There are lots of people on here who have had amazing success with the low carb/keto diet and go into remission. As you are not diabetic but prediabetic going low carb to bring your blood sugars down, then adjusting your diet to see how many carbs your body can handle would mean you mat swerve that diabetic label. Ed for grammar .
 

AndBreathe

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That's interesting. Thanks Melgar. I also had a full blood workup and everything was normal except slightly elevated ferritin, but I think that was because I'm on a contraceptive pill that means I don't bleed so probably have higher iron than is considered "normal" for women my age who tend to be iron deficient. My Triglycerides level was 0.4-0.6 (across the 3 tests), which I believe is within the normal range of 0-1.6.

My carb intake is already pretty low. I've used My Fitness Pal since 2016 (for maintenance rather than targeted weight loss) and I'm always under the 50% target for carbs and average about 40%. I'm also always up on Protein (23% vs. target of 20%), so I was really at a loss when the Diabetes Nurse asked me "what we're going to do about it."

If you don't mind me asking, were you diagnosed with T2D on the basis of your HbA1c? If so, did you get a 2nd opinion? I'm just curious as to how reliable the tests are given my experience and what they expect you to do if you already have a good diet?
It's a long time since I used My Fitness Pro, so forgive if I'm asking a really obvious question. You refer to 50% as a target (and you are usually c40%); what is that 50% of please?
 

Dee_UK

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Messages
10
Type of diabetes
Prediabetes
Treatment type
I do not have diabetes
Yes, I was diagnosed from my HbAc1 results, I did get them down to prediabetic levels on a very low carb diet, but to be honest I was expecting my new HbAc1 results to be in the low 5’s but they were 6.3. Not high I know, but still in a range that can damage your vascular system in the long term. That was 9 months of low carbing for little in return. So I figured there is something else going on. As in keeping with most people who go on a low carb diet, my Ac1 results should have been a lot lower. One may suggest I was not in nutritional ketosis but I was. I‘m at a loss. My Trigs were 0.6. I don’t share any of the classic type 2 features other than my age of onset. Someone remarked on one of the forums here that type 2 is nothing short of a dumping ground for anything that is not autoimmune, it does seem that way. In short it doesnt help people who don’t fit the classic type 2 profile. We are left high and dry. I have bent too many ears on here and with my diabetic team about my own situation because it’s like shouting into the wind. There are no answers at the moment. Now saying all that about my situation doesn’t mean going low carb will not work for you. Everyone is different and it is certainly worth giving very low carb A go. There are lots of people on here who have had amazing success with the low carb/keto diet and go into remission. As you are not diabetic but prediabetic going low carb to bring your blood sugars down, then adjusting your diet to see how many carbs your body can handle would mean you mat swerve that diabetic label. Ed for grammar .
Yes that sounds familiar. The Diabetes Nurse that I spoke to on the phone couldn't suggest anything other than attending the Diabetes Prevention programme but my Dad went on that for a year and although he did very well (lost 10kg and got his HbA1c out of the pre-diabetic range) I knew they would only tell me to eat sensibly and follow "the plate" which I've already been doing for several years. My Dad cut out cakes, biscuits, pork pies and cheese but I didn't eat any of those to begin with! I've never had a sweet tooth, don't eat between meals and only eat deserts on the rare occasion that we have a meal out. My Husband can't have Cow's milk or fruits (due to high salicylates) so we don't even have deserts in the house. I have an average of 14-20 units of alcohol a week, which I don't consider excessive, but as soon as I said that of course the DN leapt on it and told me that must be where I'm going wrong. It's literally the only "treat" I have in my life (1 glass of Wine with Dinner 5 nights a week and maybe 2 on a Saturday). If everyone that drank that much was diabetic, I think we'd all be diabetic!! It's very frustrating but I agree with you that they just want to put you in a "box" and won't hear that there could be another explanation. In my case, I think something must be causing the extreme discrepancies between the results, but they can't explain it and I think they'd rather I just accepted their results and kept quiet If my latest set of results are right though, all I've done is give up 1 sugar in tea once a day and that's brought it down from 44 to 37 but I'm sure that can't be right. Edit: typos and emoticons came out wrong!
 
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Dee_UK

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It's a long time since I used My Fitness Pro, so forgive if I'm asking a really obvious question. You refer to 50% as a target (and you are usually c40%); what is that 50% of please?
My overall food intake. The target is 50% and I'm on average ~40% every week. I'm slightly over on fat but I don't think that affects HbA1c and my BMI is OK. I'm always slightly over on protein because I eat a lot of fish and meat but I'm always low on Carbs. See the screenshot I just took from my diary
 

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catinahat

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@Dee_UK I just thought I'd chip in with something you might not be aware of.
None of the tests are perfectly accurate, they all have a margin of error.
I believe the Hba1c is plus/minus 6%. Which is much better than the finger prick tests which are +/-15% .
That 6% could go some way to explain the difference in your rest results, when you consider different lab's doing the testing, rounding results up or down and the fact that both results could be higher or lower by 6%. A difference between test results seems almost inevitable
 

Dee_UK

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@Dee_UK I just thought I'd chip in with something you might not be aware of.
None of the tests are perfectly accurate, they all have a margin of error.
I believe the Hba1c is plus/minus 6%. Which is much better than the finger prick tests which are +/-15% .
That 6% could go some way to explain the difference in your rest results, when you consider different lab's doing the testing, rounding results up or down and the fact that both results could be higher or lower by 6%. A difference between test results seems almost inevitable
Yes, that's what the lab said and I would say even up to 10% would be expected but my initial results differed by 18-20% in the space of a week. That surely can't be normal?
 
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catinahat

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Yes, that's what the lab said and I would say even up to 10% would be expected but my initial results differed by 18-20% in the space of a week. That surely can't be normal?
Obviously something seems off, it's possible that one of your results was outside of the 6%.
When I was diagnosed the Dr wanted 2 tests a few weeks apart, when I queried the need for 2 tests, the answer was to confirm the result just incase of a mess up at the lab. So it's obvious that mistakes can and do happen
 
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Alexandra100

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On average probably about 120-133g
I think this may be the explanation for your higher than desired A1c. If you can bear to, you could try the experiment of reducing your carbs further. Everyone is different. Some can tolerate more carbs than others. Myself, I try to keep down to 10 net carbs = c. 20 total carbs daily. Everyone has to balance out the inconvenience of eating really low carb against the hoped for benefits of lowering A1c, and reach their own personal compromise. Are you testing with a meter or CGM in between A1c tests? You might find the "Beat Diabetes" Youtube videos by Dennis Pollock inspiring and even helpful. Good luck!
 

Dee_UK

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Obviously something seems off, it's possible that one of your results was outside of the 6%.
When I was diagnosed the Dr wanted 2 tests a few weeks apart, when I queried the need for 2 tests, the answer was to confirm the result just incase of a mess up at the lab. So it's obvious that mistakes can and do happen
Thank you. Yes, that's what I was wondering when I posted this thread, whether others had experienced similar fluctuations or if it was unusual. I've asked the GP Surgery to request the lab to investigate. It just seems odd that I can get such a wide range of results (44, 35, 45, 34, 37) all within 3 months! I just want to know which one is right!
 

Dee_UK

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I do not have diabetes
I think this may be the explanation for your higher than desired A1c. If you can bear to, you could try the experiment of reducing your carbs further. Everyone is different. Some can tolerate more carbs than others. Myself, I try to keep down to 10 net carbs = c. 20 total carbs daily. Everyone has to balance out the inconvenience of eating really low carb against the hoped for benefits of lowering A1c, and reach their own personal compromise. Are you testing with a meter or CGM in between A1c tests? You might find the "Beat Diabetes" Youtube videos by Dennis Pollock inspiring and even helpful. Good luck!
Thanks Alexandra, the problem is that I don't know if I need to reduce my carbs or not because 2 of the 5 results I've had since Feb have indicated that I'm pre-diabetic but 3 have been within the normal range.

I'm reluctant to reduce my carbs further without knowing for sure if it's necessary because I don't need to lose weight and I only have 22.8% body fat as it is, so I'm not sure ketosis would be good for me. I also love Zumba and do 2-3 x 45-50 minute classes a week, for which I need energy to burn. I'm not testing because my HbA1c only indicated pre-diabetes, so my current glucose levels are ok.

I really just need to know what might be causing the wild fluctuations in the HbA1c from different blood samples seemingly from week to week. It just doesn't make sense to me, but thank you for the tips.
 

silky1

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I was convinced for a very long time that I had diabetes - GP would not accept it. I saw a Neurologist who agreed wtih me about the diabetes - did a standard test which came back 10.9 - so he requested a repeat test and HbA1c - this test came out at 15.9 and my HbA1C of 106 - OMG I was in shock.
That was 9 years ago - levels have fluctuated a lot since then - but since January 2021 - my levels have sat around 44/45 - although my last one was up to 48 - but I have been on something of a "self-destruct" after having Sepsis followed by Potassium poisoning - giving me an Acute Kidney Injury on CKD - with an e-GFR of 16
 
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Dee_UK

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Prediabetes
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I was convinced for a very long time that I had diabetes - GP would not accept it. I saw a Neurologist who agreed wtih me about the diabetes - did a standard test which came back 10.9 - so he requested a repeat test and HbA1c - this test came out at 15.9 and my HbA1C of 106 - OMG I was in shock.
That was 9 years ago - levels have fluctuated a lot since then - but since January 2021 - my levels have sat around 44/45 - although my last one was up to 48 - but I have been on something of a "self-destruct" after having Sepsis followed by Potassium poisoning - giving me an Acute Kidney Injury on CKD - with an e-GFR of 16
Wow! That sounds very scary indeed. Hope you can get it back down and wish you a speedy recovery x