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Re: [IP] Mixing of H and V: summary report
I'm very interested in your study. Except that for me, the results seem to be more clear cut. I can get pure humalog sites to last anywhere from 1-4 days with a wide variety of bumps and a bump about 1/2 the time. Velosulin sites last at least 4, often 6-8 day and in the last year (6 months of which I used velosulin), I had one site that had to come out after 2 hours from soreness, redness and irritation. The 5:1 mix is better than H, but the 4:1 mix seems to have fewer bumps although not to last longer. This last item, though, I have not paid as meticulous attention to as the h:v comparison. Having said all that, I should add that humalog by itself makes my sites itch as does regular (instead of velosulin) and the mix does not often cause this. I wonder if the reaction to the insulin is what causes the problem? If so, those people who have little reaction might very well not see any of the differences that are so vivid in my own experience. It's not unlike the time when
humulin first came out -- there were reports that different individuals tolerated humulin, beef insulin, beef & pork insulin, pork insulin differently. Some had skin and hypertrophy reactions with one or another, others did not, some were downright allergic. I don't know if that's correct but it does seem quite plausible.
> Discussion: At least for this experimental study on one individual, there was no obvious difference between the pure and mixed insulins. If there are any benefits of the buffer in the Velosulin, it was not apparent in my body . Would it be different if the mix was 3:1 instead of 5:1? I don't know, but I don't think it would make much difference for me personally. I think that the primary reason why a site becomes limited is the tissue reaction to the physical trauma caused by a foreign thing being stuck in it. Proof of this explanation comes from the fact that sites with the stainless steel bent needles don't last even half as long as those with the teflon catheters. Since both materials are not allergenic and don't react with body tissues, the only difference is the much greater tissue damage caused my movements of the stiff needle.
> Several other points are worth noting. In my case, there was a tendency for sites to be more stable in my hip rather than my abdomen. That is, of the ten 1+ sites, seven were in the hip, and two of the three 3+ sites were in the abdomen. This is likely to be very subject dependent, or as they say, YMMV. I don't have a lot of body fat, and this may be an important factor. Another observation from this study is that there did not seem to be any problem with leaving the Humalog or mixture in the pump and tubing for as long as 11 days. There have been several anecdotal reports of Humalog degrading more readily than Regular, and this was emphasized recently on John Walsh's website (http://www.diabetesnet.com/news.html). However, despite this study being done in the summer (including a week on the beach at the Outer Banks, NC), there wasn't any clear trend associated with whether the 4-day cycle was started with fresh insulin from a new syringe or after the insulin had been in the syringe
> for 8 days. There number of 1+ sites were equally distributed among the three 4-day cycles for a single syringe. Two of the three 3+ site were on the last cycle, but this requires more data to determine if this is a reproducible finding.
> Conclusion: There was no advantage of mixing Velosulin with Humalog (in a 1:5 ratio) on infusion site stability. Although others may believe there is some benefit of such mixing, it would be nice to see some similar experimental data in support of these anecdotal reports. _____________
> Wayne Mitzner
> Department of Environmental Health Sciences
> The Johns Hopkins School of Hygiene and Public Health
> 615 N. Wolfe St.
> Baltimore, MD 21205
> Tel. 410 614 5446
> Fax 410 955 0299
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