Can hba1c be too low?

pavlosn

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I found another reason to have 5.5 and not 6.5
http://www.diabetes.co.uk/what-is-hba1c.html
Research has also shown that people with type 2 diabetes who reduce their HbA1c level by 1% are: [1]

@jack412

This is a link to the full study from which the above numbers were extracted:

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC27454/

The study concluded that the lowest risk is associated with normal hba1c of 6% or lower ( median value 5,6%)

Unfortunately, it uses less than 6% as the lowest statistical band examined and as far as I can see it does not answer the issue of risk associated with sub 5% hba1c.

You are right in saying that it supports reducing further than 6%
 

Susiespearish

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Having just had an HbA1c test myself that was not reflective of my daily self monitoring numbers, I did some investigating.
My last result was 42 mmol/mol. According to the converter tool (
http://www.diabetes.co.uk/hba1c-to-blood-sugar-level-converter.html) that's an average of 7 mmol/L. However, I've only had 2 postmeal levels above 7 in the last three months. Based on my meter readings my average should be around 5.5 mmol/L, which should result in an HbA1c of 5.1 mmol/mol.

One thing we all like to do on this forum is post our numbers without consideration of the accuracy of them, with a few acceptions.

So, with respect to how well HbA1c reflects blood glucose levels I found this (http://labtestsonline.org/understanding/analytes/a1c/tab/faq/):


"4. Why are my A1c and blood glucose different?
Beyond the difference in units used to report them, the A1c represents an average over time while your blood glucosereflects what is happening in your body now. Your blood glucose will capture the changes in your blood sugar that occur on a daily basis, the highs and the lows. Each blood glucose is a snapshot and each is different. The A1c is an indication that "in general" your glucose has been elevated over the last few months or "in general" it has been normal. It is inherently not a sensitive as a blood glucose. However, if your day-to-day glucose control is stable (good or bad), then both the A1c and blood glucose should reflect this. It is important to remember the time lag associated with the A1c. Good glucose control for the past 2-3 weeks will not significantly affect the A1c result for several more weeks.

In addition to this, it is also important to remember that glycated hemoglobin and blood glucose are two different but related things. For unknown reasons, some peoples' A1c may not accurately reflect their average blood glucose."

I looked for graphs of HbA1c versus average blood glucose and all I found was this (http://care.diabetesjournals.org/content/25/2/275.long):

View attachment 9552

So the conversion from HbA1c to average blood glucose levels should be taken with a grain of salt...or sugar.

I also found this discussion: "Why hemoglobin A1c is not a reliable marker": http://chriskresser.com/why-hemoglobin-a1c-is-not-a-reliable-marker

And of course the HbA1c only reflects an average number and does not tell you how much time you've spent at elevated levels.

In addition, the accuracy of the HbA1c test is +/- 6%.

One thing I've learned on this forum and researching type 2 diabetes is that we are all different. Almost all of these studies are based on large numbers of people, which means that it's not always applicable to look at our own numbers and predict what it means for us. So just because your HbA1c is a certain number, that doesn't necessarily translate into the average glucose level as someone else with the same HbA1c number.

So, to address your original question, I think the lower your blood glucose (fasting, postmeal, and HbA1c) is the better, with a few caveats: 1) you're not going hypo, 2) it's through diet and exercise, but not a crazy diet or a crazy exercise regime, 3) it's not with meds.

I posted on thIs subject a short while ago .My HbA1c has never reflected by daily BG numbers .I had never had a reading in sin gle figures ever since I got the machine yet previous HbA1c's registered as 86.It has slowly caught up and is now registering as 109 but it's accuracy is certainly in question to base a drug regime on .I now take my meter to every consult .
 
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NoCrbs4Me

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I don't low carb remember?
Or as you say (duh!)
Many that's why I work with my HCP, as I accept it works as well, rather than insist there is only one possible recommended diet?
You are very confusing. You disagree with my statement, yet, to control your blood glucose levels you intentionally don't follow the official government recommended diet. I give up.
 
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pavlosn

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Guys can we leave the subject of diets out of this thread please and return to the original issue which is Hba1c and whether it can be too low.

Thank you for your cooperation

Pavlos
 
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pavlosn

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I posted on thIs subject a short while ago .My HbA1c has never reflected by daily BG numbers .I had never had a reading in sin gle figures ever since I got the machine yet previous HbA1c's registered as 86.It has slowly caught up and is now registering as 109 but it's accuracy is certainly in question to base a drug regime on .I now take my meter to every consult .
An hba1c of 86 is equivalent to average blood sugars of 13,3 while 109 corresponds to average glucose of 16,7. You do not necessarily need single figure readings to get these kind of averages. Having said that you know your numbers best and if you think your Hba1c score is not in line with your averages I will not dispute it.

It is known that some people may renew their blood cells faster than the three month average. For these people hba1c understates their true glucose average because their blood cells are new and the glucose has not had enough time to attach to them.

Unusual hemoglobin may be another reason for discrepancies.
 
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Susiespearish

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An hba1c of 86 is equivalent to average blood sugars of 13,3 while 109 corresponds to average glucose of 16,7. You do not necessarily need single figure readings to get these kind of averages. Having said that you know your numbers best and if you think your Hba1c score is not in line with your averages I will not dispute it.

It is known that some people may renew their blood cells faster than the three month average. For these people hba1c understates their true glucose average because their blood cells are new and the glucose has not had enough time to attach to them.

Unusual hemoglobin may be another reason for discrepancies.

Pavlos .I was consistently getting readings in the 20's for weeks which weren't reflected in the test .Luckily with my meter in tow I was able to show them the readings .On the main subject of how low is healthy.I was told last week by my Endo that I should never go below 6 and in fact the target he's set me is for 7.5 although I do have a heart condition and high BP .My husband who is a non diabetic (tested) throws highs of 9 and 11's regularly but normally has a fasting average of around 5.4/6 on a daily basis .
 

daddys1

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Therefore until the difference in treatment available to people based on where you live is rectified, it is no wonder that some people, myself included at the time, don't take diabetes as serious, or don't understand the implication of badly managed diabetes. I know I didn't. It was only when I saw the liver specialist, who was blunt with the truth and I hit rock bottom, did I seek alternative help.

Hi Kezzer, I feel the same , I was diagnosed Pre Diabetic some 9 months before being diagnosed fully Type 2 but no one mentioned how serious this was until full diagnosis, Yes I went off to lose weight but was not encouraged to look up diabetes given no information, just told "lose some weight you will be OK". I started eating fruit, didn't do that before, had less fat and to top it all had Majool Dates, one of the most sugary fruits you can mention, at least 4 a day for over 9 months thinking I was doing myself good.

When I got the Big 'D' diagnosis, I could not believe how stupid I had been, but no one had even mentioned what I should have been doing.

Neil
 
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douglas99

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@jack412

This is a link to the full study from which the above numbers were extracted:

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC27454/

The study concluded that the lowest risk is associated with normal hba1c of 6% or lower ( median value 5,6%)

Unfortunately, it uses less than 6% as the lowest statistical band examined and as far as I can see it does not answer the issue of risk associated with sub 5% hba1c.


You are right in saying that it supports reducing further than 6%

It states the normal range is 4.5 to 6.2, but the only conclusion it seems to suggest is that the normal range is best, ie less than 6, as far as I can understand the report.
 
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pavlosn

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Pavlos .I was consistently getting readings in the 20's for weeks which weren't reflected in the test .Luckily with my meter in tow I was able to show them the readings .On the main subject of how low is healthy.I was told last week by my Endo that I should never go below 6 and in fact the target he's set me is for 7.5 although I do have a heart condition and high BP .My husband who is a non diabetic (tested) throws highs of 9 and 11's regularly but normally has a fasting average of around 5.4/6 on a daily basis .
The guidelines do state that the target hba1c should be set by the doctor in consultation with the patient and after taking into consideration the patient's individual circumstances.

Did your doctor give you a reason for asking you to stay above 6 ( is that fasting level?)

Are you on medication that could cause you to go hypo for instance such as insulin or gliclazide?
 

pavlosn

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It states the normal range is 4.5 to 6.2, but the only conclusion it seems to suggest is that the normal range is best, ie less than 6, as far as I can understand the report.
It also states that the median hba1c within the normal range is 5,6% but you are right it just groups all normal range Hba1c scores together and does not examine any subgroups within that.
 
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douglas99

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It also states that the median hba1c within the normal range is 5,6% but you are right it just groups all normal range Hba1c scores together and does not examine any subgroups within that.

I missed that.
If the median is 5.6, of a range of 4.5 to 6.2, it would be a skewed distribution anyway, as the mean is 5.35.
 

Susiespearish

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The guidelines do state that the target hba1c should be set by the doctor in consultation with the patient and after taking into consideration the patient's individual circumstances.

Did your doctor give you a reason for asking you to stay above 6 ( is that fasting level?)

Are you on medication that could cause you to go hypo for instance such as insulin or gliclazide?

Yes Pavlos,this was in a discussion before I commence insulin and a higher dose of Sitagliptin.My consultant was also involved in a recent study quoted by @smidge stating the increased risks of of cardiac events when on insulin so with my present heart condition and a great deal of meds for that I can only assume he's worried about that .Our target is 7.5 .Thank you for posting the graphs and data .It has made interesting reading .:)
 
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douglas99

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Yes Pavlos,this was in a discussion before I commence insulin and a higher dose of Sitagliptin.My consultant was also involved in a recent study quoted by @smidge stating the increased risks of of cardiac events when on insulin so with my present heart condition and a great deal of meds for that I can only assume he's worried about that .Our target is 7.5 .Thank you for posting the graphs and data .It has made interesting reading .:)

There's something new learnt everyday with diabetes.
I suppose it's always going to be a fine line balancing everything in the right place.
You sound like you've got an excellent consultant though.
 
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LucySW

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I watched a recorded lecture few weeks ago, it was one of those from the Libra presentation. The lecturer made a valid point about T1's and to paraphrase what he said .....Hba1c is an average and the lower it is the more time the patient has spent being hypo.

But it isn't an average. That's the point. It's an amount that increases incrementally as additional hemoglobin particles are glycosylated. Hypos don't cut HbA1c, or even show up in HbA1c numbers at all.
 
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LucySW

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I tried to take the risk of hypos out of the equation. Like you I am a t2, who is not on medication that are likely to lead to hypos, so they are not a major concern to me.

The above studies are actually dealing with non diabetics so risk of hypos was never an issue, yet they still indicated increased all purpose mortality below a certain hba1c level.

I appreciate that a lot of us are unlikely to reach so low that this becomes a practical issue but it is still something to bear in mind.

Pavlos
Pavlos,,

Have a look at Jenny Ruhl's summary of the latest findings from the ACCORD study. That's the one that seemed to associate lower HbA1cs with increased mortality.

http://diabetesupdate.blogspot.dk/2014/12/accord-final-analysis-lowering-blood.html?m=1
 

LucySW

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According to my nurse anyone can go hypo although in a healthy person the body makes a recovery without help. A healthy person is unlikely to go hypo so badly and so often as to affect the Hba1c whereas a person taking medication can.
Hypos don't affect HbA1cs. They don't show up in them. HbA1cs are a cumulative measure that can't be lowered at all by anything. They can only not be raised in the first place.

When they go down it's because the Hb cells/molecules have died.
 

pavlosn

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But it isn't an average. That's the point. It's an amount that increases incrementally as additional hemoglobin particles are glycosylated. Hypos don't cut HbA1c, or even show up in HbA1c Nebraska at all.
Can you please explain this further or provide a relevant link.

As I currently understand it hba1c ( in % terms at least) is a measure of the proportion of our hemoglobin that has been glycated I.e has a glucose particle attached.

The rate at which hemoglobin is glycated and hence Hba1c depends on the concentration of glucose in the blood. The higher concentration of glucose the higher the rate at which hemoglobin will be glycated and the higher the Hba1c.

A hypo is a period when our glucose concentration although lower than normal is still positive, not negative.

During a hypo I would expect hemoglobin to continue to be glycated but at a slower rate (assuming that there is no minimum glucose threshold for glycation to occur).

So a hypo, being lower than our average glucose count, will cause our average to decrease, while actually still causing hemoglobin to be glycated (albeit at a lower rate), so still contributing to increased hba1c.

The complication is that our blood cells are continuously being renewed (on average every three months) so theoretically if the rate of increase of glycated cells slows down beyond the rate at which the glycated cells are replaced with fresh ones, then hypos would cause the proportion of glycated hemoglobin and hence hbA1c to decrease. I do not know if this is a practical possibility though.
 
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sanguine

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I think you're both right. Rate of glycation (or whatever the word is) will depend on the BG level in the blood. This acts on the positive side of the HbA1c balance. The negative side is when glycated blood cells die and are replaced by new blood cells, but the haemoglobin cells can't be 'deglycated' when still viable. The longevity of blood cells varies and is a subject in itself, but as a rule of thumb we assume it to be around 2-3 months.

As for hypos, I would expect glycation to still be occurring at a reduced rate as Pavlos says (we may be wrong on this) but unless you have them frequently and for long periods I can't see that it would have much affect on the HbA1c any more than an occasional spiky meal would.
 
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LucySW

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So a hypo, being lower than our average glucose count, will cause our average to decrease, while actually still causing hemoglobin to be glycated (albeit at a lower rate), so still contributing to increased hba1c.

The complication is that our blood cells are continuously being renewed (on average every three months) so theoretically if the rate of increase of glycated cells slows down beyond the rate at which the glycated cells are replaced with fresh ones, then hypos would cause the proportion of glycated hemoglobin and hence hbA1c to decrease. I do not know if this is a practical possibility though.

My understanding is that the rate of hemoglobin glycation will be lower not only during hypos, but whenever blood glucose levels are low to normal. That is, the rate will be a curve, not a line. So it will accelerate gradually, rather than going from hypo level in a straight line up to high blood glucose levels.

So the factor determining low HbA1c would be the total amount of time spent with blood glucose levels below a certain threshold, the threshold at which for each individual at any given time the rate of glycation increases. Which is a circular definition of course.

I shall have to go away and do some work on this.
 
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