Told to raise HbA1c

[Spiker]

I don't think that it's a threshold. If that were the case then you would have people with almost no glycated haemoglobin and that isn't the case/

I think that's conclusive. The HBA1C of non diabetics with perfectly normal BG all the time isn't zero. It's "target". Hence HBa1c is allowing us to measure deviation from target / normal and will even allow recording of values that are below target / normal.

Disclaimer: I follow Bernstein, so target = normal.

 

[phoenix]

Can I just add that the'complicated'link I put had something I hadn't seen before " There are indications that hyperglycemia itself may also reduce red blood cell lifespan".

 

[smidge]

Mmm...yes, I admit it was me who raised this. HbA1c is definitely not an average in the true sense - I pushed my consultant on this and he confirmed.

There are two issues with HbA1c as far as averages go:

1. Not all values in the range are equal - they have to be to be an average (unless you are somhow accounting for a weighting) - but HbA1c is weighted disproportionately to the later period of time;

2. High levels have a greater weighting than low levels (the controversial bit!!) Because HbA1c measures glucose attached to haemoglobin, you add to this with every level above 0, but you don't get minus points for having a low BG - you just don't attract as many glucose molecules attached to your red blood cells. So, it cannot be an average - if you see what I mean!

It's a bit complicated, but definitely not an average which would be total sum of BG divided by number of tests/readings/measurements.

I don't think I've explained that very well LOL - I wish I could articulate my thoughts better!

Smidge

 

[LucySW]

2. High levels have a greater weighting than low levels (the controversial bit!!) Because HbA1c measures glucose attached to haemoglobin, you add to this with every level above 0, but you don't get minus points for having a low BG - you just don't attract as many glucose molecules attached to your red blood cells. So, it cannot be an average - if you see what I mean!

It's a bit complicated, but definitely not an average which would be total sum of BG divided by number of tests/readings/measurements.

That's what I got from the earlier discussions, that A1c will be affected upwards by high BG but not affected downwards by low BG. That's the crucial point for what information A1c is actually offering us, is it not. So what do people think? Is that correct?

I'm a bit limited here by a non-science background. These processes are multi-factorial and complex, not certainties or simple equations. So you guys with science background have an advantage.

LSW

 

[Spiker]

First of all as @phoenix pointed out above, even normal non diabetic stable levels of blood glucose cause a positive impact on HBa1c. Even if hypoglycaemic levels left no positive contribution to glycation of haemoglobin, that wouldn't be relevant. Clearly, normal target ranges (and presumably at least part of the sub target range) make a contribution to glycation and thus to HBa1c.

The further logic is, even if low blood glucose levels did not cause any accumulation of glycosylation of haemoglobin, low blood glucose levels would still affect (reduce) the aggregated HBa1c value.

So in that sense, it is *similar to* an average, in that a middling value of HBa1c could reflect a middling value of blood glucose over 90 days, or it could conceal a mix of too-high and too-low blood glucose over the 90 days. In that sense I don't think it's totally incorrect to call it an "average" in the non technical sense of the word. A better non technical word to use for HBa1c might be that it's an "aggregate". But it doesn't change the essential point that an on-target or normal HBa1c *may* indicate a mixture of above-target and below-target (hypoglycaemic) blood glucose periods.

Coming back to the original question, in my view HCPs are right to *investigate* low HBa1c but wrong to *assume* it implies hypos in every case. The first thing they should do is look at the meter averages and the meter SD (standard deviation). If the meter average matches the HBa1c and the SD is good, the patient should be congratulated, and studied as an example of success. If the SD is bad, then give the advice to relax the tightness of control. If the SD is good but the meter average does not match the HBa1c, that's an ambiguous case. If a CGM isn't available then the patient should be asked to test more frequently and at regular intervals through the day, to see if there are lows that aren't being recorded by the meter but which are being 'recorded' by the HBa1c.

 

[Spiker]

... that A1c will be affected upwards by high BG but not affected downwards by low BG. That's the crucial point for what information A1c is actually offering us, is it not. So what do people think? Is that correct?

No it's not correct, not in the way that matters, and it's very important to understand that it's not correct. See previous post. It is not the easiest concept, definitely.

 

[Spiker]

Thinking of it this way may be useful:

Your eventual HBa1c at the end of a month (or whatever period) is affected by periods of low blood sugar, in exactly the same way that your bank balance at the end of a month (or whatever period) is affected by putting less money in, or no money in, on any given day (assume you are a taxi driver or waitress etc and get paid some money every day). Then, at the end of the month, your bank balance tells you whether you put a lot of money in that month or not a lot. (Let's assume it's a savings account and no withdrawals are allowed). If the balance is low, you know you didn't make many contributions that month. You know you made less than usual, that's undeniable. What your bank balance can't tell you is whether you made a smaller payment every day, or some big payments some days and some really low or nil payments other days.

Same with HBa1c - the big deposit days are the high blood sugar days and the low (or maybe nil) deposit days are the low blood sugar days.

The arithmetic is a bit different but that's the logic pretty much exactly, I think.

 

[tim2000s]

Can I just add that the'complicated'link I put had something I hadn't seen before " There are indications that hyperglycemia itself may also reduce red blood cell lifespan".

This is something I was aware of and told by my consultant. Typically a diabetic with a high average bg level has a roughly three month lifespan of red blood cells. This is lower than someone with a normal bg level, which is typically four months.

It also means that if you reduce your bg level during the period prior to your hba1c you may extend the life of your highly glycated blood cells and show an incorrectly high hba1c, even with an average bg level over the previous two months that equates to a lower hba1c.

 

[Fayefaye1429]

Hey guys it's nice to read people can get to around 6. Mine has alway been 7.5 and I am alway told to get it down. Trust me I do a lot of tests alter accordingly but I just can't get it down I find. I have and always will be a strong believer I. Take care of your diabetes and it will look after you. Any tips on getting my h lower?

 

[Spiker]

It also means that if you reduce your bg level during the period prior to your hba1c you may extend the life of your highly glycated blood cells and show an incorrectly high hba1c, even with an average bg level over the previous two months that equates to a lower hba1c.

Unless the more highly glycated red blood cells die earlier.
Still in a steady state it would be accurate, just less accurate during major changes.

 

[birchy66]

Hi, Birchy66, Apologies for the extra paragraph in your reply - as explained above, i got replies muddled, i think i just got so annoyed when i read your post, realising that some doctors were apparently still making such stupid comments. These can be hurtful and are completely pointless and sap motivation. Next time remind him or her that type one diabetes still leads to a lot more hospital admissions, more ill health, more costs to the NHS treating various complications etc, (and that if comprehensive studies regarding adults were done even more problems and costs might be uncovered - see the recent unsettling study by Bristol university concerning children - http://www.bristol.ac.uk/news/2015/april/type-1-diabetes.html. ) Surely your doctor should be welcoming the fact that you that you are a bit obsessive about your numbers - and appreciating that by being that way you are probably helping to save NHS costs. At the very least, the more you watch your numbers the less likely you are to be admitted to hospital with DKA or serious hypos. Ann

Hi ann34, sorry a bit late in replying to you and yes I agree with everything you say. I'm usually a fairly calm person and would tend to reflect on what the doctor said to me rather than verbally hit him between the eyes. It does make me wonder of this type of comment has a costly effect on the NHS, not to mention the patients themselves. I shall carry on as before and strive for the lower numbers, safely of course.

 

[LucySW]

This is something I was aware of and told by my consultant. Typically a diabetic with a high average bg level has a roughly three month lifespan of red blood cells. This is lower than someone with a normal bg level, which is typically four months.

It also means that if you reduce your bg level during the period prior to your hba1c you may extend the life of your highly glycated blood cells and show an incorrectly high hba1c, even with an average bg level over the previous two months that equates to a lower hba1c.

@Indy51 posted a link about this too. - As (perhaps) in the HbA1c / mean BG discrepancy I was complaining about yesterday here? Mean BG having clearly fallen over three months according to two different data sets, but HbA1c having gone up from 39 to 41?

The source she posted was this.

 

[Dillinger]

The further logic is, even if low blood glucose levels did not cause any accumulation of glycosylation of haemoglobin, low blood glucose levels would still affect (reduce) the aggregated HBa1c value.

I can't get my brain around this. Surely, low blood sugar would just not increase the glycosylation of haemoglobin? It wouldn't reduce it? At most low blood glucose levels would be neutral? If I were running blood sugars that would give an HbA1c of 10 in old money for 50% of the time and 4 for the balance that wouldn't give me an HbA1c of 7 it would give a figure weighted to whichever 50% was happening prior to the test (on the basis of the most recent events having the most influence?) which is not an average.

Best

Dillinger

 

[LucySW]

I can't get my brain around this. Surely, low blood sugar would just not increase the glycosylation of haemoglobin? It wouldn't reduce it? At most low blood glucose levels would be neutral? If I were running blood sugars that would give an HbA1c of 10 in old money for 50% of the time and 4 for the balance that wouldn't give me an HbA1c of 7 it would give a figure weighted to whichever 50% was happening prior to the test (on the basis of the most recent events having the most influence?) which is not an average.

Best

Dillinger

Yes, echoed, I don't follow how lower glucose levels cd affect the HbA1c figure. Except by Tim's point about cell lifespan, above.

 

[Spiker]

Spiker said:
The further logic is, even if low blood glucose levels did not cause any accumulation of glycosylation of haemoglobin, low blood glucose levels would still affect (reduce) the aggregated HBa1c value.

I can't get my brain around this. Surely, low blood sugar would just not increase the glycosylation of haemoglobin? It wouldn't reduce it? At most low blood glucose levels would be neutral? If I were running blood sugars that would give an HbA1c of 10 in old money for 50% of the time and 4 for the balance that wouldn't give me an HbA1c of 7 it would give a figure weighted to whichever 50% was happening prior to the test (on the basis of the most recent events having the most influence?) which is not an average.

Best

Dillinger

See my "bank balance" analogy further up for what I'm trying to say. Let me try to restate it. I don't think I'm disagreeing with what you say, just putting it another way.

Hb1aC is an aggregate measure of the glycation of haemoglobin over a period of time.

Any BG above zero (or some low threshold) will have some positive effect on glycation of haemoglobin at that specific point in time

Any increase or decrease in BG will have a relative effect (up or down) on the aggregate glycation of haemoglobin over a period of time

Therefore a low BG has an effect (downward) on the aggregate glycation of haemoglobin. Low BG doesn't have a downward effect on the glycation of haemoglobin at any specific point in time, but its reduced effect at certain points in time gives a reduction in the aggregate glycation.

So I am saying there are grounds for an HCP to suspect possible hypo BGs when they see an HBa1c below 6% or whatever. Where they are wrong is to think that the lower HBa1c is proof of hypo BGs. It isn't. It's just grounds for further investigation using Standard Deviations on meter data, or just by looking at all the meter data. And maybe getting CGM data if the meter data is ambiguous.

Is that clearer? I think we are saying the same thing.

 

[Charisma_1630]

It's ridiculous. My last one was 7.0 and I saw my nurse at the GP and she said well wel aim for 6.5 nowadays so try and lower it. You can't win either way!! I asked for how to lower it more and she offered me a leaflet which she had already given me 1 year earlier which was no help at all

 

[Daibell]

Hey guys it's nice to read people can get to around 6. Mine has alway been 7.5 and I am alway told to get it down. Trust me I do a lot of tests alter accordingly but I just can't get it down I find. I have and always will be a strong believer I. Take care of your diabetes and it will look after you. Any tips on getting my h lower?

Hi. What sort of diet are you on? What is your BMI?

 

[Dillinger]

@Spiker - thanks, I'm just trying to understand, I'm not doubting what you say!

 

[Spiker]

@Spiker - thanks, I'm just trying to understand, I'm not doubting what you say!

Yeah me too, it's not the easiest of topics. No worries.

 

[LucySW]

See my "bank balance" analogy further up for what I'm trying to say. Let me try to restate it. I don't think I'm disagreeing with what you say, just putting it another way.

Hb1aC is an aggregate measure of the glycation of haemoglobin over a period of time.

Any BG above zero (or some low threshold) will have some positive effect on glycation of haemoglobin at that specific point in time

Any increase or decrease in BG will have a relative effect (up or down) on the aggregate glycation of haemoglobin over a period of time

Therefore a low BG has an effect (downward) on the aggregate glycation of haemoglobin. Low BG doesn't have a downward effect on the glycation of haemoglobin at any specific point in time, but its reduced effect at certain points in time gives a reduction in the aggregate glycation.

So I am saying there are grounds for an HCP to suspect possible hypo BGs when they see an HBa1c below 6% or whatever. Where they are wrong is to think that the lower HBa1c is proof of hypo BGs. It isn't. It's just grounds for further investigation using Standard Deviations on meter data, or just by looking at all the meter data. And maybe getting CGM data if the meter data is ambiguous.

Is that clearer? I think we are saying the same thing.

Spiker, what you’re saying is this, right? (Or wrong, as the case may be.) Glycation requires high BG to increase (as, if I don’t keep paying client invoices into my business account, it won’t grow); but low BG, while it doesn’t contribute to the glycation ‘balance,’ isn’t making any withdrawals from the account. So high BG is a necessary condition for an increase in the accumulated glycation, while low BG is a sufficient condition for stopping the glycation balance increasing, exercising curb on its growth.

You said: Therefore a low BG has an effect (downward) on the aggregate glycation of haemoglobin. Low BG doesn't have a downward effect on the glycation of haemoglobin at any specific point in time, but its reduced effect at certain points in time gives a reduction in the aggregate glycation.

But don't you mean a curb on the expansion of the aggregate glycation? It can stop its great future happening, but it can't do anything to actual glycation?

Sorry to go on, but I would like to understand what we're talking about.