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[IPk] Re: HbA1c

I think Jackie is absolutely correct here, in that any glucose molecule
in the blood, regardless if it was originally part of the most stickly
sweet or chocolate or part of an apple, can form a molecule of
glycosylated haemoglobin. The questions about why Danielle's HbA1c is
higher than Barbara's must relate either to the fact of less good
overall control (i.e. more time spent with high BG, due to a less good
balance between carbohydrate intake and insulin injected, perhaps
relating to the amount of high glycaemic index foods, but perhaps not)
or to other factors. 
Regarding high glycaemic index foods (and ignoring the thought that
eating a lot of high GI foods may not be so healthy for anyone,
diabetic or not), the action curve for a given insulin is not exactly
the same for everyone. For example, some people (like me) can often
return very nicely to normal BG within 1 - 1.5 hours after eating say a
piece of cake with the right bolus of humulog. But things can be
complicated - for example if I then ate another identical piece of cake
during that time, and gave another identical bolus, I would not get
back to normal BG without further adjustment, because I would not have
started off at normal BG when eating the second piece. One thing that I
learnt from using the CGMS a few years ago was that bolusing a little
in advance of eating can improve the match of the insulin bolus and
high carb foods, resulting in faster return to normal BG - but I'm not
sure if this is practical for kids - it isn't always practical for me
Another factor that can influence HbA1c is bleeding - for example due
to menstruation - if you lose some of the glycosylated haemoglobin
through bleeding, your body then synthesizes more haemoglobin that is
not initially glycosylated, so regardless of how high your BG's, your
HbA1c will be a little lower than if you were not losing blood each
month due to menstruation.
Also some people just have higher HbA1c than others - for reasons that
are not completely understood.
> Hi Barbara
> Well I see what the nurse is getting at, but if I have grasped things
> correctly about glucose metabolism and the binding of glucose to the
> red
> blood cells ('glycosylated haemoglobin) this isn't quite the full
> explanation.  Whatever the cause for the raised BG, the blood cant
> differentiate between what was originally sweet food and other
> starchy food
> that was processed into glucose.   So as far as the body is concerned
> it
> doesn't matter what the source of the glucose came from.  However the
> effect
> of the higher glycaemic food is that it is taken into the blood steam
> at a
> much faster rate and then there are post meal high blood glucose
> levels for
> quite sometime after eating these.  If you looked at a graph of the
> blood
> glucose levels, plus the graph of the insulin action, you would see
> that
> with some high glycaemic foods that the lines don't marry.  Which
> means that
> the glucose in the blood is raised before the action of the insulin
> can
> begin to work.  This means that during this period where the actions
> don't
> marry that there is glucose binding to the red cells.    So if you
> checked
> Danielle's BG after eating sweets, she may well spike up quite high,
> but if
> you check the BG 1.5 to 2 hours later, her levels would be back to
> normal
> and you would necessarily know what had happened.   I suppose if you
> have
> more fast acting glucose to deal with, the harder it will be to
> exactly
> match the glucose levels and insulin action.  Novorapid and Humalog
> don't
> work quite as fast as people think they do.
> The way around this maybe to eat less sweets, cakes etc, to eat sweet
> food
> after eating a normal meal, so that the lower glycaemic foods slow
> down the
> absorption.  Chocolate and ice cream are absorbed more slowly due to
> the
> high fat content, so might have less of a spike.  Maybe its time to
> think
> about weaning Danielle off some of the sweeter foods which are not
> good for
> anyone, whether they have or haven't got diabetes.  If she's not
> eating that
> much stuff, then just try and make it at different times, or bolus
> the
> correct amount before she eats.  Don't do this with chocolate or ice
> cream
> unless you know they spike up high.  I once sent Sasha hypo by giving
> her
> insulin with ice-cream.  Though I cant remember if this was when she
> had
> untreated coeliac.
> Looking back now at your nurse's original comment, I suppose her
> explanation
> is actually correct, its just that she hasn't quite given the full
> explanation for it.
> Not all carbohydrates are created equal, nor will they all affect
> your blood
> sugar in the same way. Maybe its time to review the  glycaemic index
> that
> ranks foods according to their ability to raise blood sugar.  I think
> maybe
> I will have to look at this too, although I still find the actual
> amount of
> carb rather than the glycaemic index is the factor that has the most
> effect.
> I suppose its one thing we can watch out for when we get a pump if we
> are
> not dropping the HbA1c and is a good reminder that its worth taking
> the
> glycaemic index into account.  A lot of Sasha's Gluten free stuff is
> very
> high on the gycaemic index and there's not a lot I can do about it.
> Glucose sticks to the haemoglobin to make a 'glycosylated
> haemoglobin',
> called haemoglobin A1C or HbA1C. The more glucose in the blood, the
> more
> haemoglobin A1C or HbA1C will be present in the blood.
> http://medweb.bham.ac.uk/easdec/prevention/what_is_the_hba1c.htm
> Jackie, England UK
> Mum of Sasha aged 10 dx 1999, twin sister Rebecca, both coeliac 2001
> Mum also to Danni and Nicola, wife to Terry
> - -----Original Message-----
> From: email @ redacted [mailto:email @ redacted]
> Sent: 07 January 2005 11:29
> To: email @ redacted
> Cc: email @ redacted
> Subject: [CWD UK] HBA1c
> Hi everyone
> Danielle's nurse came to see us the other day to run through her
> latest
> HBA1c results. Danielle is on the pump and I am diabetic too and on
> Lantus
> and Novorapid with meals.  I don't take very much insulin compared to
> Danielle and I also have lower HBA1c results than Danielle. 
> Basically, I am
> on the poor man's pump and Danielle has the pump attached to her so
> she
> should be getting better results than me.  Well................
> I don't eat cakes and chocolates but Danielle eats loads of that sort
> of
> thing.  OK, if I did eat cakes and chocolates I would allow for it
> when I
> take my fast-acting insulin, but Danielle allows for it when she eats
> chocolate and sweets.  So, you might ask why her HBA1c is always
> higher than
> it should be.  I didn't know this until last week.  Our DSN told us
> that
> because Danielle is eating the sugary stuff, it is sticking to her
> red blood
> cells and this is causing the higher HBA1c.  Even if she gives the
> insulin
> for it, the sugar is still sticking.
> Can anyone else agree with me on this?  This is new to me because I
> thought
> if you ate the stuff and bolused or gave fast-acting insulin, it
> would
> rectify and balance out the blood sugar.
> This is very interesting isn't it?  The plot thickens.
> Barbara
> Mum to Danielle aged 10, pumping since Nov 2002
> - ----------------------------------------------------------
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