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Another opinion, was: Re: [IP] Site absorption

Michael wrote:

>Site degradation within 36-48 hours of a site change is usually a
>sign of sensitivity to Humalog and can most often be eliminated by
>mixing Velosulin or regular insulin in small quantities with the
>Humalog. The subject of mixing H and V or R has been discussed in
>many threads on the list. I would first encourage you or anyone else
>suspecting a sensitivity to H to use some other insulin for a week or
>two to verify that whatever symptoms you see that makes you suspect a
>sensitivity GO AWAY on straight Velosulin or Regular. I know it is a
>pain to use a slower insulin, but the time needed to verify your
>suspicions is short. Many people have skipped this step successfully,
>but my engineering background makes me suspicious and prone to want
>solid answers first :o)


As a pumper who has carefully followed this thread from it's original 
inception several years ago, I'd like to add some comments:

1)  Site degradation within 36 - 48 hours of a site change *MIGHT* be a 
sign of sensitivity to Humalog *OR ONE OF IT'S COMPONENTS*. I have to 
disagree with the comment that degradation is *USUALLY* a sign of 
sensitivity to Humalog.

2)  There are many variables involved in the subcutaneous absorption of 
insulin. These variables may include: formulation of the insulin; type of 
infusion set; brand of infusion set (not all infusion sets are the same); 
presence of insulin antibodies; location of infusion site; lack of / 
presence of scar tissue; depth of insertion of infusion set; interaction of 
any / all of these variables. There are other variables, I'm sure.

Each of these variables can affect each pumper differently. Combinations of 
these variables add to the complexity of troubleshooting. In other words, 
YMMV - Your Mileage May Vary. I'd also like to add - YSMV - Your Science 
May Vary <grin>

>The question has come up periodically about mixing Humalog and
>Velosulin or regular insulin to reduce or eliminate infusion site
>corruption / loss. There is substantial ancedotal evidence that this
>mix solves the immediate problem however WHY is not clearly
>understood. Around 5% of pumpers report a sensitivity (not an allergy)
>to Humalog that is mediated by mixing a small amount of Velosulin or
>regular with the H.


I'm a relatively thin person, and I have always used Tenders as my "set of 
choice". As many others have noted, toward the end of the second day, most 
certainly by the third day, my BGs would start to "creep" upward. This was 
usually solved by changing my infusion set. Note that I experimented many 
times with mixing H and V. I wasn't happy with the results.

I finally arrived at a "solution" which appears to work quite well for me - 
using an infusion set with a different length cannula. For the past two 
months, I've been using infusion sets which insert at a 90 degree angle to 
the skin surface. The soft cannula appears to be exactly the right length 
for me - 10 mm. For years, I resisted using a 10 mm set (this length was 
always available as a metal needle set - Disetronic Rapid), thinking I was 
"too thin".

The 10 mm Ultraflex Soft has been a good solution for me. I've been 
consistently getting a full three days from each of my infusion sites, and 
often am able to approach the fourth day with no noticeable "creeping 
upward" of BGs. In fact, my problem now is remembering to change my 
infusion set. The "third day upward creep" of my BGs used to be an 
indicator that my infusion set needed to be changed. Since I don't see that 
now, I have to rely on my logs and notes to remind myself to change my site.

>Current science indicates that the underlying
>problem is related to lispro chemistry and the presence of lispro
>monomer in the tubing. What is going on in the tubing set appears to
>be an interaction between lispro, the tubing  and any human insulin in
>the formulation. It is believed that the addition of Velosulin
>competes for lispro monomer and that the lispro-insulin heterodimer is
>more stable than the lispro-lispro dimer. Most pumpers who decide to
>try this method (my daughter included) use 5 parts of Humalog and one
>part of Velosulin.

I'm glad to hear that "Bill and his crew" are finally chasing down this 
possibility. It had been suggested a number of times on this list in the 
past, as well as in private e mails to Mr. Van Antwerp. Sometimes, it takes 
a while to solve these things. It will be interesting to follow up with 
pumpers using Novolog. That may be an option many of us have been looking for.

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