High/Low HBA1C's and control overall?

[getcarter76]

Can you have a good HBA1c but be badly controlled overall and/or a high HBA1c but have good control overall?

Just wondering after pondering from different comments here and there and throughout....many thanks

Bernie xx 🙂

 

[everydayupsanddowns]

I've had some on-target HBa1c results after periods when I've known my bgs have been zig-zagging like mad. I'm not sure where I heard it but I believe can be a little like an average, in that a few hypers and hypos can cancel each other out. I may well be completely wrong though!

M

 

[shiv]

Oh yes - Sam is a good example of this (sorry to call her out but I know she won't mind) - her hba1c is 6.5% but this is due to huge swings on a daily basis!

A hba1c is almost like an 'average' of the amount of glucose that's stuck to your cells, or something along those lines.

 

[Andy HB]

The other thing is that HbA1c is more heavily weighted to the more recent weeks.

So, you could have had really bad control earlier and then better control more recently. The HbA1c would tend to only reflect the good control in that circumstance.

That's why the spot bg checks can still be quite important.

Andy

 

[FM001]

Sure you can have a good hba1c and still have be badly controlled. The test is only a average of the previous 6-8 weeks, so if you are attending clinic annually then it is a very poor indicator of the previous 12 months overall control. There has been studies that suggest diabetics improve and monitor their control more tightly prior to a clinic appointment and then lapse again once having attended, I know this is not the case for the majority on this message board, but in my younger years I was guilty of this on a regular bases. More important than a a1c test is your everyday control, the a1c takes no account of the hyper's and hypo's experienced or frequency, but regular testing each day and recording your bg's in a diary and presenting this at your clinic will undoubtedly give a more accurate portrayal of your diabetes control. Although I may have sounded a little dismissive of the a1c test in what I have written, but a good result can only be welcoming if it truly reflects your everyday control, so if your control looks like a roller-coaster ride then it isn't really worth the paper it is written on! Toby.

 

[novorapidboi26]

I agree with most, it only relfects the las 2-3 months, the more often you can get the test the better.............

A diary for me is the best way to evaluate your control, it means you can make your own avergae at regular intervals, however I am sure the HbA1c test is a bit more complicated than adding and dividing........

 

[wallycorker]

Can you have a good HBA1c but be badly controlled overall and/or a high HBA1c but have good control overall?

Just wondering after pondering from different comments here and there and throughout....many thanks

Bernie xx 🙂

Hi Bernie,

The HbA1c is an average of what has been happening to your blood glucose readings over the last three or four months.

Because of that you are extremely unlikely to get "a good HBA1c and be badly controlled overall and/or a high HBA1c but have good control overall".

The HbA1c is really a very good measure of a diabetic's overall control.

However, a lowish HbA1c reading could still mask some fairly high spikes and it is these that are supposed to be harmful as far as the possibility of developing complications is concerned. In my opinion, it is important that a diabetic tries to maintain blood glucose levels as near to normal as possible - i.e. around 4-8 mmol/l at all times and an HbA1c below around 6.5% and lower if possible. Of course it may not always be possible to achieve these levels.

Best wishes - John

 

[everydayupsanddowns]

Hi Wallycorker

I think you are right in terms of T2s not on medication, but hypoglycaemic events can skew the figures.

In the blood stream are the red blood cells, which are made of a molecule, haemoglobin. Glucose sticks to the haemoglobin to make a 'glycosylated haemoglobin' molecule, called haemoglobin A1C or HbA1C. The more glucose in the blood, the more haemoglobin A1C or HbA1C will be present in the blood.

Red cells live for 8 -12 weeks before they are replaced. By measuring the HbA1C it can tell you how high your blood glucose has been on average over the last 8-12 weeks. A normal non-diabetic HbA1C is 3.5-5.5%. In diabetes about 6.5% is good.

However from a study entitled Assessing Glycemic Control in Diabetes: From Self Monitoring of Blood Glucose to Continuous Glucose Monitoring System:

It was observed that between HbA1c level and the period spent in glycemic values more than 180 mg/dl there is not as direct a relationship as we expected.

Basically, if you have lots of hypos you can cheat your HbA1c lower.
M

 

[rachelha]

Hi Bernie
I spent years trying to get team to acknowledge that although my hba1c was not awful (8.5ish) it was due to constantly swinging blood sugars. I did graphs of my results for my appointments which looked like the Himalayas. Eventually they gave me a CGMS for a week and then they finally believed me.

 

[rossoneri]

I think you are right in terms of T2s not on medication, but hypoglycaemic events can skew the figures.

... from a study entitled Assessing Glycemic Control in Diabetes: From Self Monitoring of Blood Glucose to Continuous Glucose Monitoring System:

It was observed that between HbA1c level and the period spent in glycemic values more than 180 mg/dl there is not as direct a relationship as we expected.

Basically, if you have lots of hypos you can cheat your HbA1c lower.

M,
Thanks for highlighting the study. I am just a little confused by the terminolgy used in the above quote from it- not untypical when I am reading an extract from a medical study!! 🙄
Would not a glycemic value of more than 180 mg/dl be for a high blood sugar? Or does the glycemic value rise as the blood sugar falls?
If a higher glycemic value is the equivalent to a higher blood sugar then this would appear to suggest that it is hypers that skew the HbA1c result rather than hypos.

 

[everydayupsanddowns]

M,
Would not a glycemic value of more than 180 mg/dl be for a high blood sugar? Or does the glycemic value rise as the blood sugar falls?
If a higher glycemic value is the equivalent to a higher blood sugar then this would appear to suggest that it is hypers that skew the HbA1c result rather than hypos.

180mg/dl is the US version - for us mmol/l types it's 10mmol/l.

I read it like this (I'm paraphrasing and making wild assumptions here, but I didn't want to spend 25 euros on the full report and the other reference I found was Wikipedia 🙄 )

We expected a pretty direct relationship between time spent over 10mmol/l and 'highness' of the HbA1c:
Over ten lots = high HbA1c, not over 10 lots = low HbA1c
But we didn't find that. Some people were over 10 lots, but still managed a good HbA1c. So something else is clearly going on...

Add this to my own anecdotal experience of good A1cs after a period of wildly swinging hypo-to-hyper bgs plus conversations with a Consultant and DSN in the past saying that a few hypos can skew your HbA1c result, and I now treat HbA1cs as a good target/guide, but not necessarily a very accurate measurement of my overall control.

Still nice to get a good one though!

 

[Andy HB]

The HbA1c is an average of what has been happening to your blood glucose readings over the last three or four months.

Because of that you are extremely unlikely to get "a good HBA1c and be badly controlled overall and/or a high HBA1c but have good control overall".

John, as you probably know, HbA1c is not a true average. It is weighted to the more recent weeks. Consequently, it is quite possible for someone to have good control in the more recent weeks thereby more than offsetting any poor control earlier.

So, it is quite feasible to have a good HbA1c but poor control overall, depending on the timescales of each HbA1c test.

However, you are quite correct in saying that someone is "extremely unlikely" to get a high HbA1c and have good control overall for obvious reasons!

Andy

 

[rossoneri]

180mg/dl is the US version - for us mmol/l types it's 10mmol/l.

I read it like this (I'm paraphrasing and making wild assumptions here, but I didn't want to spend 25 euros on the full report and the other reference I found was Wikipedia 🙄 )

Add this to my own anecdotal experience of good A1cs after a period of wildly swinging hypo-to-hyper bgs plus conversations with a Consultant and DSN in the past saying that a few hypos can skew your HbA1c result, and I now treat HbA1cs as a good target/guide, but not necessarily a very accurate measurement of my overall control.

Still nice to get a good one though!

Ok yes I thought glycemic value was what we will soon be moving to and yes I stuck to just reading the summary too!

My own current status is that I still have too many hypos for my liking but not many high blood sugars but with those results I regard the HbA1c value as a good 'average' albeit weighted towards the later part of the three months prior to the test. the next time I see my DSN I will ask whether they think hypos skew the results by themselves rather than it being just when they are combined with swings to high values too.

I am a big fan of getting your HbA1c values too and on a regular basis. I remember the days before they were the standard part of your review and your doctors had no way to know how unstable your values were unless you were doing regular tests and were prepared to be honest when you shared your results with them. At least not until you started suffering the complications! 😱 The HbA1c also does give equal weighting to times of day when you do not manually test regularly e.g. when you are asleep.

OK the next part is for all the geeks amongst us, I apologise in advance to the rest of you but I cannot help myself sometimes 😱

One further point, how to measure if you are being more successful in reducing your BG swings over time?
I currently test using the Accu-Chek meter that comes with my Combo pump. On this meter there is a facility to get the reading averages for 7, 14, 30, 60 and 90 days together with the associated Standard Deviation (SD). I will not go into details here about what the SD is but you can read about on this wiki page if you want to know more. Basically for a given average the smaller the SD then the less variation from that average.
An average of 6.0 with an SD of less than 2.5 is therefore quite good for the points at which you are testing, the same average with an SD of 5.0 probably suggest too many out of range peaks and troughs - although that is just my unqualified opinion! One way I have monitored my efforts at reducing my swings is to see if this SD is falling or not.
If your meter does not provide an SD value you could probably obtain it from any software that manages the values downloaded onto a PC or if you keep a record of your values on a spreadsheet then it is a fairly standard spreadsheet function.

 

[Robster65]

Ditto what's been said so far. I used to improve before seeing the consultant and then lapse into not bothered mode.
My best doctor ever was the first to admit to me that they don't know from HbA1c whether it's a smooth response or peaks and troughs, and whether it mattered either way. This was a good few years ago.

We use SiDiary which gives an estimated HbA1c (yet to see how accurate it is) and gives SD values. I hate statistics but will try to pay more attention to it from now on. 😱

Rob

 

[sofaraway]

I think that my meter gives standard deviation but i wasn't sure what was good and what i should be aiming for. My HbA1c is good, but I suspect as low as it it because of too many hypo's. I am hoping to reduce the numbers of these and with that I expect my A1c to rise, but for me this would actually be improved control.

 

[newbs]

I wouldn't have thought you can have a bad HbA1c if you have good control but you can definitely have a good HbA1c with bad control - my recent HbA1c was 6.7 but I have rarely had an actual reading of 6.7, mostly 12 or higher and loads of hypos in the high 2's/low 3's, not much on target! This is really frustrating as when I go along to the diabetic clinic they always say I have no worries because my HbA1c is good. Even though I tell them that my control is not good it is shrugged off and I am told my control is too tight! 😡

 

[everydayupsanddowns]

I wouldn't have thought you can have a bad HbA1c if you have good control but you can definitely have a good HbA1c with bad control - my recent HbA1c was 6.7 but I have rarely had an actual reading of 6.7, mostly 12 or higher and loads of hypos in the high 2's/low 3's, not much on target! This is really frustrating as when I go along to the diabetic clinic they always say I have no worries because my HbA1c is good. Even though I tell them that my control is not good it is shrugged off and I am told my control is too tight! 😡

If you are concerned, take your logs with you and ask them to comment on them. HbA1c is still regarded as the 'gold standard' test for overall control and research into complications risk tends to use it as a criteria for assessing how likely complications are to arise.

I have heard about reports though which suggest rapid spikes/lows are quite bad for your microvascular system (eg eyes) despite potentially being masked in a good HbA1c. This concerns me because from what you've said our patterns would be quite similar. Like you my good HbA1cs have always attracted 'You're doing really well, dont worry about it' type comments.

Levelling the graph is my new focus!

 

[Adrienne]

Any good medical team knows that you cannot solely rely on a HbA1c. If you have a good result ie under 7.5 % (anything above is not a good result) and you know that it is due to good levels then you can rely on it. If you know that your good result is due to highs and lows (and either can swing the result) then your team will acknowledge this.

This is why the NICE guidance is as it is for obtaining a pump. There is not just the one criteria of 'if over 7.5% you get a pump' there are other criteria as well as well informed teams and others know that the HbA1c is not totally reliable.

We all strive to get great HbA1cs but not have hypos to get there.