Talk:Glycated hemoglobin

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Glycation vs. Glycosylation

Glycation is NOT enzyme mediated, while glycosylation is enzyme mediated. Hence, I think the appropriate term to be used is glycated Haemoglobin, not glycosylated Haemoglobin. Reference: Harrison's principle of internal medicine, 17ed, Chapter on Diabetes Melitus. —Preceding unsigned comment added by Tjelong (talk • contribs) 11:59, 7 September 2009 (UTC)[reply]

I have changed the references to 'glycosylation' in the main body of the article to 'glycation' where appropriate, as I think they must recently have been altered. I haven't had a chance to check the references yet but I will do that asap. FlowersAndFilth (talk) 08:05, 5 April 2012 (UTC)[reply]

Merge

Merge. Let's keep Glycosylated hemoglobin and have HbA1C as a redirect. -- Boris 19:48, 10 February 2006 (UTC)[reply]

I feel that it is important to distinguish between glycosylation of proteins and glycation. Glycosylation is something that happens to a protein as it is being synthesized and is genetically determined based on protein sequence. Serines and threonines within the protein, particularly in the context of other residues, are recognized by the enzymatic machinery of the cell. Complex carbohydrate structures are then added on to the terminal hydroxyl groups on these two amino acids. I am unaware of any data to suggest that glycosylation has deleterious effects on protein function. In contrast, non-enzymatic addition of sugar residues to proteins in the extracellular compartment occurs in all human beings (and in other mammals), but the rate at which this occurs is greatly increased in diabetes mellitus. The non-enzymatic reactions involved were first characterized by a French biochemist, Louis-Camille Maillard. There is an initial addition of reducing sugars such as glucose and fructose to primary amines in proteins to form Schiff bases, and a subsequent Amadori rearrangement resulting in the formation of the ketone.

Interpretation of HbA1c Results

The table for conversion of HbA1c result to Average Blood Sugar in mg/dL,shows that for HbA1c of 6 & 7 the Average Blood Sugar is 120 mg/dL and 150 mg/dL respectively. However, the refernce [1] cited in the article has the coversion as 135 mg/dL& 170 mg/dL for Average Blood Sugar. Which one is accurate? --Ugaap 15:38, 13 February 2007 (UTC)[reply]

Also for this section, the article and reference state the "normal" range for the test is "4-5.9%", but I'm reading right from an NHS results slip (in UK NHS) the normal range given is "4.4-6.2%". If this is something that varies between countries or hospitals, as I expect all results do, perhaps this should be noted in the page.--163.160.252.16 (talk) 14:27, 16 October 2008 (UTC)[reply]

References

  1. ^ http://www.medicinenet.com/hemoglobin_a1c_test/article.htm

Etymology?

Sorry if I missed it, but I couldn't find the derivation of the term "A1c" in the article or here. Anyone know it? David 15:32, 22 October 2007 (UTC)[reply]

The name A1c is historic. When purifying hemoglobin A (consisting of two alpha and two beta subunits), one of the minor subfractions found was called A1. This was further separated by Huising et al. into three subfractions, called A1a, A1b, and A1c. At the time, nobody had any idea what these different fractions were chemically, so the naming is arbitrary and can only be understood from the history of discovery. It appears difficult to incorporate this information into the article.  Andreas  (T) 01:53, 23 October 2007 (UTC)[reply]
    • Using above paragraph which is is quite explanatory, suitably worded in context, the information on A1c should be placed on the article page.

Patelurology2 (talk) 13:44, 9 August 2012 (UTC)[reply]

NDEP says the preferred term is "A1C"

I appreciate the discussion about the various terms. This appears to have been a problem for others as well. Here is a memo from The National Diabetes Education Program [1]:

—

TO: All NDEP Partner Organizations

DATE: September 7, 2001

FROM: NDEP Executive Committee

RE: NDEP Adoption of A1C – a Simple Name for Hemoglobin A1c

The National Diabetes Education Program (NDEP) Steering Committee has agreed to adopt a simple name for the hemoglobin A1c test that is used to monitor long-term blood glucose control. The new name “A1C” will be used in all NDEP communications with people with diabetes. NDEP’s market research with consumers and health care providers indicated a need for a simple name for the test and that A1C was the most acceptable choice. As a result:

• All NDEP partners are urged to use the simple name A1C in all communications with people with diabetes that mention the test.

• All NDEP partners are urged to inform their constituents/members that NDEP is promoting use of the simple name A1C with people with diabetes and to ask for their support of the name’s use.

—

Note that it uses upper case "A" and "C." I have been using this term in my scientific and medical writing with no pushback from editors or reviewers for several years now. It seems like we ought to address this name explicitly. Ben 23:53, 26 October 2007 (UTC)[reply]

Interesting if that is how officially will be known in US, but in UK (and I suspect elsewhere in world) HbA1c will continue to be used.(eg from National Institute for Clinical Excellence Management of type 2 diabetes - Managing blood glucose levels (Guideline G) (PDF) see section 3.1) Also, the term is useful because it is quite apparent what is being tested (ie glycosylated haemaglobin, and as red blood cells survive for about 120 days, so HbA1c test gives meaning information over glucose levels in the last 6weeks).David Ruben Talk 03:44, 27 October 2007 (UTC)[reply]
Assuming I've not entirely used an incorrect search expression, but PubMed for 'A1C NOT("HbA1c") NOT("hemoglobin A1c") NOT("haemoglobin A1c")' gives 679 hits, so does not seem scintific literature yet favours this vs alternatives tabulated above. David Ruben Talk 03:52, 27 October 2007 (UTC)[reply]

How about to check: Clin Chem Lab Med 2007;45:1081-1082 ? —Preceding unsigned comment added by 84.206.43.2 (talk) 10:19, 26 November 2008 (UTC)[reply]

Glucose HbA1c equivalence

Equation just cited for better conversion but no citation given for it,[2] and values only added in mg/dl (ie mmol/L not changed with that). Having reverted, I now agree having found the source (it is a later paper to that curently cited). But I've not got time now to correctly update whole table. The reference markup though will be:

<ref name="pmid11815495">{{cite journal |author=Rohlfing CL, Wiedmeyer HM, Little RR, England JD, Tennill A, Goldstein DE |title=Defining the relationship between plasma glucose and HbA(1c): analysis of glucose profiles and HbA(1c) in the Diabetes Control and Complications Trial |journal=Diabetes Care |volume=25 |issue=2 |pages=275–8 |year=2002 |month=February |pmid=11815495 |doi= |url=http://care.diabetesjournals.org/content/25/2/275.long}}</ref> David Ruben Talk 07:47, 1 July 2009 (UTC)[reply]

 Done David Ruben Talk 16:18, 9 July 2009 (UTC)[reply]

I think we need to change the table dealing with estimated glucose level and A1C to the equation based on this study by the American Diabetes Association [3] (AG mg/dl = 28.7 × A1C − 46.7, R2 = 0.84, P < 0.0001) —Preceding unsigned comment added by 204.181.3.2 (talk) 19:00, 27 July 2009 (UTC)[reply]

Medicare

"Continuous blood glucose monitors are becoming more commonly used and are covered by many health insurance plans but not by Medicare."

It is possible that people who do not live in the U.S.A. or Australia are unaware of the existence of Medicare. —Preceding unsigned comment added by 203.164.154.230 (talk) 18:27, 23 April 2010 (UTC)[reply]

Factor to convert HBA1 to HBA1c

I am sorry but I am trying to find the correct factor to change HBA1 to HBA1c, I would like to know if somebody can send this factor to me and also the explanation of the way to obtain that factor.

I hope somebody can help me with that.


My name is Nancy and my e-mail address is: nancychavezch@hotmail.com

Thank's 201.216.146.23 (talk) 18:09, 2 March 2011 (UTC

Patelurology2 (talk) 14:05, 9 August 2012 (UTC)[reply]

Nathan formula

To get the average blood sugar reading from HbA1c, one can use the Nathan formula - mutiply HbA1c by 33 and subtract 86 (divide by 18 to get the figure in millimoles). ACEOREVIVED (talk) 16:03, 21 June 2011 (UTC)[reply]


New column for table needed

Would it not help if the table also included blood glucose in millimoles as well as milligrams?ACEOREVIVED (talk) 15:29, 21 July 2011 (UTC)[reply]

    • Agree. in the table use also to show results of Nathan's formula as in section above this and finally derive a simple approximation of A1C to blood sugar realizing all the time that most recent spikes of blood sugar may have had higher glycation and skewing of results.

Patelurology2 (talk) 14:04, 9 August 2012 (UTC)[reply]

I see it's done now. Mikael Häggström (talk) 19:35, 19 May 2013 (UTC)[reply]

Hemoglobin A1c Vs. Glycohemoglobin

This article implies that the terms "hemoglobin A1c" and "glycohemoglobin" are synonymous. However, I'm looking at some lab results that show separate listings for "Hemoglobin A1c" and "Glycohemoglobin", which appear to be distinct but related things. The reference range for hemoglobin A1c is shown as 4.2-5.8%, while the reference range for glycohemoglobin is shown as 4.4-8.4%. Should this article compare and contrast the two? Or should there be a separate article? --Mark D Hardy (talk) 19:42, 4 August 2011 (UTC)[reply]

Patelurology2 (talk) 13:58, 9 August 2012 (UTC)[reply]

Deleting section "Planning Treatment Response"

I am removing this section for the following reasons:
A) it pertains to management of blood glucose levels in diabetics as deduced from hba1c testing. Therefore such a section should be in either "diabetes" or "blood glucose" it is not specifically about Glycolated Hemoglobin
B) the entire section a based on a single reference which sites a list of articles.
i. a number of the referred data is old (1998/2008/2009) in a field on which research material is coming out rapidly
ii. the references are not formatted so you know which factual claim is supported by which reference
iii. The one claim I checked was flatly contradicted by the cited reference. (See below)

C) some of what this author says is already in the prior section with more nuance and recognition of general principals for treatment decisions.

D) per B above, with so much contradictory and complex scientific information out there on best treatment responses to elevated blood glucose, I do not think it is appropriate to have a short section under the wrong subject that is unlikely to be accurately curated, when treatment of DMT2 is such a serious and weighty matter, in which peopl may turn to Wikipedia as a definitive source.

Here is a claim made by the author of this section:

>"For younger adults, evidence shows that harms including increased mortality can result from using medication to seek A1c below 7.0%.[32]"



Reading the citation in footnote 32, the research paper states the exact opposite:
>"CONCLUSIONS A strategy of intensive glucose control, involving gliclazide (modified release) and other drugs as required, that lowered the glycated hemoglobin value to 6.5% yielded a 10% relative reduction in the combined outcome of major macrovascular and microvascular events, primarily as a consequence of a 21% relative reduction in nephropathy. (ClinicalTrials.gov number, NCT00145925.) — Preceding unsigned comment added by Jennpublic (talk • contribs) 01:06, 13 May 2014 (UTC)[reply]

Proposal to delete section "modification by exercise training"

Although interesting study cited, this is about effect of exercise on BG levels - as measured by A1c- not a direct effect on the blood cells themselves. I don't see that this section is claiming that exercise un-Glycates blood cells; everything I've read about exercise is rather that it reduces overall Blood Glucose load which in turn translates into lowered A1C results as hemoglobin is replaced over time.

If the author or someone else could explain whether they are talking about a direct effect on hemoglobin rather than on 90 day A1C test results.

Perhaps this and (an improved version of) the other section I already deleted should be moved into a new topic of "Glycemic Control"? — Preceding unsigned comment added by Jennpublic (talk • contribs) 01:36, 13 May 2014 (UTC)[reply]

I thinks it IS important section, just improve it. For example if a person is already thin and has only PREdiabetes, not Type 2 Diabetes Mellitus (T2DM), what helps? Any research you can find? ee1518 (talk) 14:13, 30 July 2016 (UTC)[reply]

connection to A1C lab test & G6PD deficiency?

Is it possible:

Since G6PD deficiency is the/an: "abnormality in the activity of an erythrocyte (red blood cell) enzyme. This enzyme, glucose-6-phosphate dehydrogenase (G-6-PD), is essential for assuring a normal life span for red blood cells, and for oxidizing processes. This enzyme deficiency may provoke the sudden destruction of red blood cells and lead to hemolytic anemia with jaundice following the intake of fava beans, certain legumes and various drugs" ...[4]
... and Glycated hemoglobin/A1C is a: "form of hemoglobin that is measured primarily to identify the three-month average plasma glucose concentration. The test is limited to a three-month average because the lifespan of a red blood cell is four months (120 days). However, since RBCs do not all undergo lysis at the same time, HbA1C is taken as a limited measure of 3 months" (source: this wiki page)

Would it be possible to be WNL (within normal limits) for a lab test of A1C to be low/below avg on a patient with G6PD deficiency - due to the random/sudden destruction of RBC's therefore affecting the A1C lab test results?

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Add to "Modification by diet" section

This section currently only talks about probiotics, which are really supplements, not foods (which is what would be expected in a section about diet). I was able to find one meta-analysis suggesting that a vegetarian diet can significantly lower A1c levels, which should probably be included as relevant. Full text of the meta-analysis is here: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4221319/ Figured I should run this by the community for review. Lumberjane Lilly (talk) 20:00, 2 March 2021 (UTC)[reply]

-This is a heavily biased study by Neal D. Bernard who works for the Physicians Committee for Responsible Medicine, a animal rights groups. — Preceding unsigned comment added by 89.204.135.17 (talk) 02:30, 28 October 2021 (UTC)[reply]

Claim that glucose is used as the primary metabolic fuel in humans

References 1 and 2 do not support this claim.

My limited understanding of the topic is that when glucose is present, it will be used first for most metabolism in the body, except the adult heart. Historically, external glucose isn't readily available and the body has a very limited store of glucose (~1day). It does however often have a large store of lipids, most cells , in most of us able to sustain us for months. The most common claim, the brain needs glucose to function, appears to be suspect: https://pubmed.ncbi.nlm.nih.gov/27629100/ — Preceding unsigned comment added by 73.4.118.149 (talk) 18:07, 20 January 2023 (UTC)[reply]

Rephrase "sponaneously (i.e. non-enzymatically)"

The introduction of the article, as currently written, claims equivalence between the glycation reaction being spontaneous and it being non-enzymatic. These are two entirely different properties; the spontaneity or non-spontaneity of a reaction is entirely a question of thermodynamics, while being enzymatic or not only affects reaction kinetics. It would be more accurate to simply say "Most monosaccharides...spontaneously and non-enzymatically bond with hemoglobin..." rather than introducing the non-enzymatic property with "i.e." 2603:8000:6F00:85D7:8845:84E:D215:FCAD (talk) 04:14, 16 March 2023 (UTC)[reply]

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