Great but the same insulin is used in both sterile and non-sterile environments, and I'd rather inject low levels of toxins than bacteria that can multiply. The phenol and m-cresol also maintains the stability of the hexamer form which makes non-human insulin effective.
Hi, after some time I'm back on the same topic. Why? Because one more issue with the commercially available insulins: their onset and duration of action.
In the healthy islets, with presence of Zn atoms, insulin takes hexameric (inactive) form which is also more appropriate because allows more dense packing. Commercial insulin, I agree with you is also in hexameric form around phenolic group. But I disagree- it does not make it more but less effective, lasting 3-5 hours and perfectly designed for MDI therapy.
In my modest opinion, the pump users would have the opportunity to perfectly control their BG if only they had a monomeric insulins in their reservoairs.
Look for example this article:
https://www.ncbi.nlm.nih.gov/m/pubmed/2226110/
This means that a perfect cloosed-loop systems (fully automatic pump + CGM) are possible, but somehow, they are not on the market. Besides, it would allow a diabetic to eat with less worries, even the fast sugars. Would you not like it?
So, the presence of phenol in insulin formulations is not favorable in terms of both safety and efficacy.