# Re: [IP] re: mixing insulins...another question

```> I have what may seem like a silly question, but here goes....  We
> just began mixing H & V for my son about a month ago.  His numbers
> were always higher day 2 of a site and his ups and downs were hard
> to control.  I must say that since the H/V mix, his numbers have
> been WONDERFUL!  Our endo and CDE had not mixed before but supported
> our request.  We use the 1:5 ratio, and here's the question that's
that is a 5 to 1 ratio -- that would be 4 parts H and 1 part V or are
you using  5 parts H and 1 part V ??

> been bugging me.  We use the MiniMed 507c.  When I draw the insulin,
> we do the H first then the V.  Now....Since the neck of the
> reservoir gets filled up too, I kind of "add" some V to the actual
> 1:5 ratio, to account for the "extra" H in the neck of the reservoir
> to try to keep a "true" 5:1 proportion.  Is this correct?  It's been

>From and engineering standpoint, to promote mixing you would draw the
smaller amount of fluid first -- this will allow the turbulence of
drawing the second larger amount to promote good mixing. A secondary
effect is that the resulting mix is closer to the characteristics of
the last fluid drawn. What you draw last will have a small amount of
"pure" stuff in the leur lock area. When this is infused, the
difference between the pure H and the H/V mix will be slight and any
change in effectiveness as it is used up will go unnoticed. If it
were the other way around, you conceivably could draw as much as
10-30 units of V -- which is regular -- before the mix began to enter
the system. Since the absorption time of the V is much different than
either H or the H/V mix, this could create a problem !!

As an aside, I don't really think the actual proportion is terribly
important, Lily has tried both 5/1 and 4/1. The difference is evident
but not huge -- she likes 5/1 better. The point is that if the mix
were to vary from say 5.1/1 to 4.9/1, I bet you could not tell the
difference.

Michael
email @ redacted
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