Blood Tests - HbA1c vs Fasting Blood Sugar

[Energize]

One of my friends has recently been told she is 'pre-diabetic' and so she is taking this very seriously, changing her eating habits in various ways, cutting back on obvious things, ie sugar in tea/coffee, not eating cakes, desserts and such like and she's doing very well, it seems.

The Diabetes nurse, that she has seen for the first time, was apparently surprised that my friend had had HbA1c tested but not a Fasting blood sugar and that her diagnosis was made on the basis of the HbA1c only. The nurse had apparently explained that a Fasting Blood Sugar would show what her blood sugar levels had been over the past 3 months! I said I thought she must have meant HbA1c but, no, she definitely wants my friend to have a Fasting blood sugar test when she is due a re-check in 3 months, ie March 2018

Now, I was under the impression that it was now acceptable to diagnose on the basis of HbA1c rather than requiring a certain number of random blood sugars and/or Fasting blood sugars.

I just do not understand this and wonder if the nurse is confusing the tests or just 'out-of-date'. However, I don't like to assume I know more than the nurse Can someone explain this, please, or are you as confused as I am now???

Many thanks

 

[Guzzler]

I believe the Fasting test has gone out of fashion in recent years. I was asked to do it at my old surgery but in the meantime I changed surgery's and all the tests were repeated (a delay in passing on my records) at my new practice but was told I did not have to fast at all. Hope this helps.

 

[bruciebonus]

She's probably just confused I once had a nurse telling me that insulin is produced by the pituatry gland in your brain and not the pancreas, I couldn't believe it and neither could anyone else, and no, I am not joking.

 

[lindisfel]

She's probably just confused I once had a nurse telling me that insulin is produced by the pituatry gland in your brain and not the pancreas, I couldn't believe it and neither could anyone else, and no, I am not joking.

Perhaps she meant the control of cortisol via the adrenal which affects b.g.? D.

 

[dogslife]

I haven't had to fast before a diabetic blood test for years. If I was your friend I would ring the surgery in plenty of time beforehand to ask for clarification. Maybe the fasting test is for some other reason and there was some mis-communication/ confusion??

 

[AdamJames]

One of my friends has recently been told she is 'pre-diabetic' and so she is taking this very seriously, changing her eating habits in various ways, cutting back on obvious things, ie sugar in tea/coffee, not eating cakes, desserts and such like and she's doing very well, it seems.

The Diabetes nurse, that she has seen for the first time, was apparently surprised that my friend had had HbA1c tested but not a Fasting blood sugar and that her diagnosis was made on the basis of the HbA1c only. The nurse had apparently explained that a Fasting Blood Sugar would show what her blood sugar levels had been over the past 3 months! I said I thought she must have meant HbA1c but, no, she definitely wants my friend to have a Fasting blood sugar test when she is due a re-check in 3 months, ie March 2018

Now, I was under the impression that it was now acceptable to diagnose on the basis of HbA1c rather than requiring a certain number of random blood sugars and/or Fasting blood sugars.

I just do not understand this and wonder if the nurse is confusing the tests or just 'out-of-date'. However, I don't like to assume I know more than the nurse Can someone explain this, please, or are you as confused as I am now???

Many thanks

Is there possibly a confusion over the definition of a fasting test?

I did, once get asked to provide a blood sample after fasting - and was told the fasting bit was important - but it wasn't a finger prick test, it was the needle-in-the-arm job which was sent off and used to produce the HbA1c report. So maybe some GPs believe it's best to fast for the HbA1c and some don't think it's important. If the nurse is calling it a fasting test, but also saying that it will show the average of the past few months, may that's what's happening.

 

[Ultramum]

I may be wrong but I think cholesterol is usually best tested after fasting but not Hba1c?

 

[paulus1]

fasting should not affect the hba1c test or it wouldbe pointless to do. fasting bloods were found to be less accurate. similar to the ogtt.

 

[Boo1979]

In terms ofin terms of a diabetes diagnosis anyway, a single hba1c or random / fasting blood sugar is insufficient - it requires at least 2 elevated readings over a period of time - I don know if its the same for pre diabetes but logic would say it should be - maybe thats the reason for another test? Particularly if the hba1c was toward the top of the prediabetic range

 

[Alison Campbell]

The additional data of a fasting test is useful if you know how to you use it. Although it has fallen out of favour the more data you have the clearer the picture of what is going wrong.

Prediabetics can have impaired fasting or impaired glucose tolerence or both. There are studies trying to pin point who will progress to type 2 and/or get complications and they are markedly different if you just have one of these impairements. From memory impaired fasting is more of problem and harder to deal with. Jenny Ruhl on her diabetes 101 website has to good info also why HBA1C will not necessarily catch the right people early and may catch some people as prediabetic who will never develop t2.

 

[Smallbrit]

Is there possibly a confusion over the definition of a fasting test?

I did, once get asked to provide a blood sample after fasting - and was told the fasting bit was important - but it wasn't a finger prick test, it was the needle-in-the-arm job which was sent off and used to produce the HbA1c report. So maybe some GPs believe it's best to fast for the HbA1c and some don't think it's important. If the nurse is calling it a fasting test, but also saying that it will show the average of the past few months, may that's what's happening.

I'm thinking it's this. I always have to "fast" - no food/drink other than water after midnight the night before - for morning HBAC1 tests. I thought that was normal?

I was sent away and told to reschedule when I once forgot and had a cup of coffee beforehand.

 

[Guzzler]

The additional data of a fasting test is useful if you know how to you use it. Although it has fallen out of favour the more data you have the clearer the picture of what is going wrong.

Prediabetics can have impaired fasting or impaired glucose tolerence or both. There are studies trying to pin point who will progress to type 2 and/or get complications and they are markedly different if you just have one of these impairements. From memory impaired fasting is more of problem and harder to deal with. Jenny Ruhl on her diabetes 101 website has to good info also why HBA1C will not necessarily catch the right people early and may catch some people as prediabetic who will never develop t2.

As some drugs prescribed for conditions other than Diabetes have been shown to raise fasting levels then it would be logical to summise that the 'best' fasting bloods would be from those who take no drugs at all or who are able to suspend use of said drugs long enough to clear the body so that an accurate level of one's own levels could be recorded, just pondering here.

 

[Alison Campbell]

This article and these studies are to me the most important information about prediabetes and possible progression.

http://www.phlaunt.com/diabetes/14046669.php

This is the information that explains why the 3 tests (Fasting, HBA1C and OGTT)are important to understand where you are as a prediabetic and how the cut off points can lead to wrong (over and under) diagnosis. Although it is US focussed it influences UK NICE guidelines.

http://www.phlaunt.com/diabetes/14046782.php

I would encourage your friend to take the fasting test and gather as much data as possible.

 

[Energize]

Hi all
I'm so sorry. With all the pressure of Christmas etc, I had forgotten I'd posted Hence the lack of response. My memory really isn't good.

Anyway, thanks for all your posts and information. I haven't heard any more re my friend having further testing but I will be asking her when I see her next.

Happy New Year to everyone
J

 

[X-Alexxander-X]

One of my friends has recently been told she is 'pre-diabetic' and so she is taking this very seriously, changing her eating habits in various ways, cutting back on obvious things, ie sugar in tea/coffee, not eating cakes, desserts and such like and she's doing very well, it seems.

The Diabetes nurse, that she has seen for the first time, was apparently surprised that my friend had had HbA1c tested but not a Fasting blood sugar and that her diagnosis was made on the basis of the HbA1c only. The nurse had apparently explained that a Fasting Blood Sugar would show what her blood sugar levels had been over the past 3 months! I said I thought she must have meant HbA1c but, no, she definitely wants my friend to have a Fasting blood sugar test when she is due a re-check in 3 months, ie March 2018

Now, I was under the impression that it was now acceptable to diagnose on the basis of HbA1c rather than requiring a certain number of random blood sugars and/or Fasting blood sugars.

I just do not understand this and wonder if the nurse is confusing the tests or just 'out-of-date'. However, I don't like to assume I know more than the nurse Can someone explain this, please, or are you as confused as I am now???

Many thanks

Hi, here in the USA, we take random and fasting glucose reads just to know how we are controlling our sugars and to know what foods affect our sugars. The HbA1c is an appropriate measurement of a 3 month average.

 

[X-Alexxander-X]

She's probably just confused I once had a nurse telling me that insulin is produced by the pituatry gland in your brain and not the pancreas, I couldn't believe it and neither could anyone else, and no, I am not joking.

If I ever heard a nurse tell me that, I'd get up and leave, then go elsewhere to find someone that knew better.

 

[Juicetin]

This article and these studies are to me the most important information about prediabetes and possible progression.

http://www.phlaunt.com/diabetes/14046669.php

This is the information that explains why the 3 tests (Fasting, HBA1C and OGTT)are important to understand where you are as a prediabetic and how the cut off points can lead to wrong (over and under) diagnosis. Although it is US focussed it influences UK NICE guidelines.

http://www.phlaunt.com/diabetes/14046782.php

I would encourage your friend to take the fasting test and gather as much data as possible.

Thats a very interesting link Alison. I found the quote below interesting:
"If your blood sugar did not reach 140 mg/dl (7.7 mmol/L) an hour after taking a large dose of carbohydrates and if it was below 120 mg/dl (6.7 mmol/L) two hours after you ate the large dose of carbohydrate, most health authorities would also say that you are normal. These numbers, 140 mg/dl at 1 hour and 120 mg/dl at two hours after a meal are what Joslin Diabetes Clinic of Harvard Medical School defines as upward limit of "normal.""
I think these numbers are lower than those published on the Diabetes.co.uk website? I thought that said under 7.8mmol 2 hours after eating was considered "normal" ?

 

[Bluetit1802]

Thats a very interesting link Alison. I found the quote below interesting:
"If your blood sugar did not reach 140 mg/dl (7.7 mmol/L) an hour after taking a large dose of carbohydrates and if it was below 120 mg/dl (6.7 mmol/L) two hours after you ate the large dose of carbohydrate, most health authorities would also say that you are normal. These numbers, 140 mg/dl at 1 hour and 120 mg/dl at two hours after a meal are what Joslin Diabetes Clinic of Harvard Medical School defines as upward limit of "normal.""
I think these numbers are lower than those published on the Diabetes.co.uk website? I thought that said under 7.8mmol 2 hours after eating was considered "normal" ?

Jenny Ruhl (author of that website) tends to have much less generous target levels.

This is what WHO has to say about it (page 13 to 15)
http://www.who.int/diabetes/publications/Definition and diagnosis of diabetes_new.pdf

Since there are insufficient data to accurately define normal glucose levels, the term ‘normoglycaemia’ should be used for glucose levels associated with low risk of developing diabetes or cardiovascular disease, that is levels below those used to define intermediate hyperglycaemia.