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Swabbing with Alcohol before Injecting Insulin

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Written by Ann S. Williams, MSN, RN, CDE

[07August96]
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We have had quite a discussion about the need to swab skin with alcohol 
before insulin injection.

I do recall reading a research study in _Diabetes Care_ , I think, about 
how swabbing the skin with alcohol vs. injecting through clean but 
unswabbed skin resulted in a few minor infections on the alcohol-swabbed
people, and none on the clean-but-unswabbed people. Someone, either one 
of the study authors or the writer of a later letter to the editor, 
hypothesized that perhaps some non-native bacteria migrated from the 
hands to the injection site by floating through the alcohol. Remember, 
alcohol does not kill all bacteria instantly; to kill bacteria with 
alcohol you have to let something soak for about 1/2 hour.

I also remember a later letter to the editor, a response to the article 
that briefly reported another research study on cleansing injection 
sites. The author had been working with people who rarely bathed, I 
think in a nonindustrialized country. He reported that not only did his 
team find no infection problems in the people who did bathe regularly 
(defined as at least once a week), whether they wiped with alcohol or 
not, but they also found that cleansing with alcohol did not prevent 
infections in people who did not bathe. In other words, bathing 
regularly was both necessary and sufficient to prevent infection.

Anyhow, short of autoclaving your skin, you simply cannot sterilize it.  
Human skin just harbors too many tiny living things and has too many 
little crevices where they can hide. However, we have immunity to our 
own normal skin inhabitants. If we didn't, we would constantly be sick 
from them. Those of us who have functioning immune systems are able to 
handle the introduction of tiny amounts of bacteria from our skin all 
the time, or we as a race would not have survived living in caves, in
forests, on farms, etc., where our ancestors surely had loads of cuts 
and scrapes often. And, in addition, insulin needles are not good 
carriers of bacteria; they are too small and slick to get much under 
your skin.

I checked some of the diabetes reference materials that I have here at 
home to see what I could find. Unfortunately, I did not keep a copy of 
that _Diabetes Care_ article, which appeared at least 4 or 5 years ago, 
maybe more. However, the ADA's _Clinical Practice Recommendations, 1996_ 
conspicuously omits any mention of wiping the skin with insulin before 
injection. The injection instructions (p. S33) are certainly detailed 
enough that if the ADA consensus were that alcohol wiping were 
necessary, it would be mentioned. Furthermore, among the suggestions for 
decreasing pain of injections, it says, "Waiting until topical alcohol 
(if used) has evaporated completely before injecting," implying that the
author(s) consider alcohol use optional.

Similarly, the instructions for insulin injection in the book, _Learning 
to Live Well With Diabetes_ (1991), published by the International 
Diabetes Center, conspicuously omit any mention of wiping the skin with 
alcohol; it does say, "The site you have selected should be clean." 
(p. 95)

Then I have a little book called _Management of Diabetes Mellitus_ by 
Sherwyn L. Schwartz, MD, published by NovoNordisk in 1990. (The author 
was at that time the Director of the Diabetes and Glandular Disease 
Clinic/Research Center -- San Antonio Diabetes Center of Excellence, and 
Director of Endocrine Training for Family Practice Residents for the 
University of Texas Health Science Center at San Antonio.) Dr. Schwartz 
says, (p. 94) "At this author's institution visibly clean skin without 
alcohol preparation is used for the injection site. There have been no
reports of infections in over nine years. The use of alcohol is not 
recommended due to its drying effect on the skin."

I hasten to add that cleansing skin is truly necessary for many other 
invasive procedures, such as when substances are introduced much deeper 
into the body or when a foreign object is left under the skin. However, 
the published research does not support the necessity of wiping the skin 
with alcohol before insulin injections.

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