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genetic "trojan horse "of HbA1c testing

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angusmac

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hi, my name is Angus ,a Scot living in Australia. I am also a "Vet" of type 2 diabetes -( 27 yrs.) I, like all Diabetics here,
was taught that HbA1c was the"Gold Std" for Diabetic Management.The test is a calculation of how much glucose binds to your
red blood cells or Haemoglobin, which normally has a lifespan of approx 120days in "normal" individuals.

However there is a Major Quality Assurance "Black Hole" for certain "Ethnic " groups including those of Scots/Irish Ancestry.

Some ethnic groups have an underlying blood condition called variant Haemoglobin or Haemoglobinopathy. There are over 800
Variants which can be of a non disease condition. It is a form of anemia and the Red blood cells' lifespan is shortened thus
confounding the A1c test results.!! In my case ,over the years, I had results of 3.8;4.0 5.0 etc- these were interpreted by GPs as
"Great Control"!!! On 2 occasions I was finger pricked with an A1c Meter and told "I was not Diabetic"

The following ethnic groups identified here in OZ are: Greeks;Italian;maltese'cypriots;Spanish(Southern European) Chinese;Middle
Eastern;South East Asian;Blacks (African & American);Indian Sub-continent;South American; Pacific Islanders;NZ Mauri;and
certain Aboriginal communites; This Genetic "Trojan Horse" can be passed on down generations.
As these groups are the "Migratory Birds of the World". Clinicians;educators' nurses etcs must be made aware of the "exceptions
to the Rule" of HbA1c testing ,and must compare glucose readings with A1cs to identify the condition.
REMEMBER " A diabetic's Health is on ly as good as His/her Self Management Skills Allow"

6.5 to 7% is the "target" in an A1c test. This is difficult to acheive on medication, so write down your test result ,and if it does
not relate to your glucose readings ,ie high BGLs and low A1c ,tell yor Gp to ask for a Fructosamine Test.

People who "fall thro the Net" of misinterpretation ,like myself" By GPs,do not get "managed, Medicine/insulin wise, and go on
to earlier complications

regard Angus Mac
 
That's fascinating information, Angus. Thank you so much for letting us know. I'm going to check into the fructosamine test you've mentioned. Thanks again!

Best wishes,
 
so write down your test result ,and if it does
not relate to your glucose readings ,ie high BGLs and low A1c ,tell yor Gp to ask for a Fructosamine Test
That's good advice except that so many people with T2 don't have the means to test regularly so won't know if there is any discrepancy.
The diabetes UK site mentions the use of fructosamine in known conditions I believe It is one of the reasons that was given for not using (giving to patients) the estimated average glucose calculation in the UK and elsewhere

People with the better known variants like sickle cell and Thalassisaemia will obviously know of their condition. Presumably if the variant causes anaemia then that would be symptopmatic or picked up with a full blood count. That still leaves some people with asymptomatic variants. (and the article cited below discusses this)

It also raise questions about the usefulness of HbA1c as a means of diagnosis in some people.

.

This article is quite detailed.
http://www.mlo-online.com/articles/2012 ... o-much.php
 
Hi Angus,
The points you raised are really interesting.
I've just got into this with my HbA1c reading putting me in the diabetic range at 50.
With me I think it could be the other way round (but I have had problems with my mmol/L meter that caused a red herring as well).

On this site the converter converts the equivalent of 50 mmol/mol HbA1c (6.8 ish) to 9mmol/L
Unlike you, I find it hard see my highs and lows having averaged as high as 9.0mmol/L over three months?
So I would question HbA1c as giving possible false positives as well?
So is HbA1c such a good analogue of average blood glucose?
Why have they disregarded/dropped glucose tolerance testing in the UK? (cost?).....in fact they won't do them for other than pregnancy.
regards
Derek
 
There are a couple of conditions that can yield higher HbA1c results
HbA1c is increased with conditions that increase red blood cell lifespan such as iron deficiency anaemia, vitamin B12 deficiency, folate deficiency anaemia or splenectomy [3
Click to expand...
http://www.knowledge.scot.nhs.uk/clear/ ... sease.aspx

The impetus to change the mode of diagnosis did not come specifically from the UK.
A World Health Organisation committee meets from time to time to discuss the definitions and the means of diagnosis for diabetes. They consider the available evidence (hence changes of names IDDM to T1, the lowering of the cut off points in the 1990s etc) It makes absolute sense to have international definitions, else you could be told you had diabetes in one country and not in another ( though in fact the US did jump the gun and introduce HbA1c diagnosis before the WHO.)

Hb A1c wasn't used before because there was no international standard for HbA1c ( eg Sweden and Japan had very different standardisation methods ;an HbA1c of 7% in Sweden didn't mean the same thing as one in the UK; could be very confusing) . Recently there has been agreement on the international standardisation of methods and reference materials in order to 'assure comparability of HbA1c measurements at a global level (hence the change of units in the UK, other countries including where I live haven't changed yet).
The level at which a diagnosis of diabetes is based is to do with the levels at which diabetic complications can start to appear. Apparently "HbA1c gives equal or almost equal sensitivity and specificity to a fasting or post-load glucose measurement as a predictor of prevalent retinopathy" (look at the take off points on the graphs { though be aware of the scale too, that slope at the end is potentially misleading. At the lower levels the risk, though there ,is small})
http://www.who.int/diabetes/publication ... c_2011.pdf


There are times when it shouldn't be used (eg in children, in pregnancy, when T1 is suspected or when someone is acutely ill ; the HbA1c may be meaningless in these cases)
When Hb A1c was introduced there was an editorial in the BMJ
HbA1c values are also affected by certain haemoglobin variants and haemolytic anaemia, which, along with other conditions,
affect erythrocyte survival. Severe iron deficiency anaemia should be treated before measuring HbA1c. Other conditions may interfere with the measurement of HbA1c. Most assays are based on immunochemistry or high performance liquid chromatography, and their use in specific circumstances needs to be guided by local laboratories. The prevalence of individual types of haemoglobinopathy, many of which can be identified on testing, and the assay being used must be taken into account.6
Nevertheless, HbA1c can be used to diagnose diabetes in most people.
Click to expand...

http://www.bmj.com/content/345/bmj.e7293

Personally when testing 6+ times a day, the diary programme I use (SIdiary) has always predicted my HbA1c accurately. My average meter reading though is not quite the same (it's usually a bit lower than the estimated average derived from the HbA1c) This makes sense because averages from spot readings don't take into account the length of times your blood glucose levels are at any level. )
 
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