For millions of people with diabetes, life is a constant schedule of painful injections. But scientists at Zhejiang University have taken a step closer to the dream of a needle-free treatment. In a new study published in Nature, they have unveiled a technology that allows insulin to be simply absorbed through the skin—a task that was thought impossible for decades.
What is the difficulty?
Our skin is a perfect barrier. It is designed to keep nothing out. Insulin molecules are too large and “watery” to overcome this fatty shield. To bypass this protection, scientists have created a special conductive polymer. It chemically binds to insulin, forming a single complex that works like a “Trojan horse.”
How does it work?
The secret is in changing the “masking”. The polymer reacts to the acidity (pH) of the environment. On the surface of the skin, it receives a charge that helps it literally squeeze between the protective layers of the epidermis. Once in the deeper layers, it loses its charge and, together with insulin, enters the bloodstream. Having reached the liver and muscles, this complex acts on the cells as effectively as the natural hormone, forcing them to absorb glucose.
Results and pitfalls
Tests on mice and mini-pigs showed an interesting effect. Unlike an injection, which acts sharply and quickly (which is sometimes dangerous), the cream worked more gently. It normalized sugar in 1-2 hours, but kept it stable for a record 12 hours, protecting the body from dangerous glucose spikes. No inflammation or irritation was found on the animals' skin.
However, it is still a long way from the appearance of such a cream in pharmacies. The main problem now is effectiveness. To get the desired result, scientists had to apply creams with a concentration of insulin that is dozens of times higher than the dose in a regular injection. This means that most of the precious medicine is still lost along the way.
However, this study is one of the most convincing evidences that delivering large protein molecules through the skin is possible. If scientists can improve the “absorption” of the drug, it will change the lives of not only diabetics, but also patients who need other complex medications.
