I read an article on the D-Life web site about the topical application of insulin enhancing wound healing and I’m interested to know if there’s been any other research on this. If it really works, it’d be a great way to use up expired insulin.

Your question prompted me to go back and review the existing literature on this topic. There is a recent press release from the American Society for Cell Biology. This reports results of a study where topical insulin helped healing of wounds in rats and seemed to help human skin cells in culture to increase in numbers and migrate. One of the authors on this study published some results of insulin treatment on burns in rats in 2004 (in Chinese!). Of note, this paper was presented as a poster from a submitted abstract. This means that it underwent peer review, and, although important, was not considered ready yet for an oral presentation (orals are reserved for more complete or novel studies). It also means that it has not yet been published in an open forum where others can try to replicate these results.

Insulin-like growth factors (which can cross-react with insulin receptors and are somewhat similar to insulin) have been used in studies of wound healing in humans (with some success). So far, as far as I can find, no studies of topical insulin in human skin have been done.

I would hold off on using expired insulin to promote wound healing for now. Part of my concern is that the diluents used (which give insulin that “smell” that you notice), although good for keeping insulin stable for injection, may have untoward effects on wounds. I would, however, keep watching the news for new studies on this topic.

LAD
Additional comments from Dr. Tessa Lebinger:

I had never heard of thus, but a check of PUBMED revealed several small studies of topical insulin. I don’t know why this has not been pursued further.

One study, Topical insulin in wound healing: a randomized, double-blind, placebo-controlled trial., did show improved healing with topical application of regular insulin, but it wasn’t clear whether the effect was due to the insulin itself or the zinc in the insulin preparation. Another study, Stimulated healing of recalcitrant wounds by topical application of enriched cell culture medium: a clinical report., enriched a solution with a combination of insulin, thyroid hormone, and growth hormone and showed improved healing, but it wasn’t clear which hormone or hormones were responsible.

Injecting insulin under burn wounds in rats has been reported to improve healing (the authors refer to this as “topical” administration of insulin, but it is really subcutaneous). See The influence of topical application of insulin on the formation of basement membrane in scalded rats. You might also want to read The effect of topical insulin on infected cutaneous ulcerations in diabetic and nondiabetic mice. and Two cytoplasmic 5′-nucleotidases of Bacillus subtilis K.

TGL