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Re: [IP] A1C - what's the real story here?

Here's why they test for HbA1c, and what that means...

First, there is a TWO step biochemical process at work, call glycation,
or glycosylation.  The first step is where glucose attaches to protein.
Later this new glycated protein can attach to an adjacent protein, forming
a permanent crosslink.  The second stage is the BAD thing, that leads to
much of the vasuclar complications in DM.  

Now, HbA1c measures the FIRST stage glycosylation of hemoglobin.  This gives
you an idea of how much glycosylation is happening - which is related to
the AVERAGE blood sugar levels.    This just happens to be a convienient
short life (2-3 month) protein, that will reflect how much glycosylation is
going on over the last 2-3 months.    Say if someone had a constant blood
sugar level of 50 for 1.5 months, and later had a level of 150 for 1.5
months, you would come out with what appeared to be an HbA1c that would
correspond to a blood sugar of 100 over the entire time....  That assumes
that all red blood cells were living exactly 3 months, etc - and not how
things really are exactly... :)

Since this gives you an idea of how far this bad process has gone, it can be
assumed that the process will continue to the second stage later.  The second
stage is the really bad one - that can become a permanent crosslink on long
lived proteins - such as blood vessel walls, connective tissues, etc.  

Every person that has glucose in their blood (i.e. everyone) will have some 
value of HbA1c.  The lower this value, the less chance there is that protein
will become crosslinked - or the amount of crosslinking will be less.  The
higher the value, the greater chance of a large amount of crosslinking.  This
corsslinking causes blood vessels to become less flexible, and more rigid,
leading to hardening of the arteries, etc.  This happens to the joints,
leading to joint pain, etc.   This is where the complications come from
in many cases - the second stage glycosylation of permanent proteins.

For more info on how glycosylation works, and why it is bad, take a look
at this link:


Just my two cents...


> Alright Medical Professionals out there, help us out here!  According to the
> Joslin Guide, the test "reflects the average of your glucose control over
> the past 2-3 months".  Also, it adds:
>     It is important to note, however, that in interpreting tests for
> hemoglobinA1, near-normal results don't necessarily mean that you have
> maintained acceptable blood sugar levels on a day-to-day basis.  In fact, a
> satisfactory reading may actually reflect the average of some very high and
> very low blood sugar levels during the eight-week period.  In such cases,
> the amount of sugar that becomes attached to the hemoglobin could be similar
> to readings obtained when blood sugar is consistently closer to normal.  You
> could be getting a distorted view of what has really occurred.
> In the John Hopkins Guide, the following is offered:
>     If glycated hemoglobin provides the big picture, it doesn't give the
> WHOLE picture.  It does not, for example, tell you whether the overall
> control is fairly stable at a particular level or whether you have many
> highs averaged in with many lows.
> These two books have been my "diabetes bibles" for the past few years...are
> they steering me wrong on this?  And no, I'm not "anti-HbA1c testing" - I do
> understand the benefits it can provide by lettinng you know that if it is
> NOT in aggreement with you self-monitering records, then something may be
> happening when you are NOT testing that needs looked into...there's a lot of
> value in that, as sort of a double-checking system.  What I AM worried about
> is people seeing a "good" HbA1c & believing that means all is well, & that
> it indicates good control overall with no highs & lows involved.
> Since we've got different resources giving us different information
> here...anyone have some good strong light they can shed on the topic?
> Sammi
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WB0DPN - Pueblo, Colorado
direct email: email @ redacted
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