Insulin, a hormone generally known for regulating blood sugar levels, can also speed up the healing process when it is applied directly to the skin.

Rats treated with topical insulin healed wounds faster. The same result was found in follow-up studies on human skin cells in culture.

Insulin stimulates human keratinocytes, which are cells that regenerate the epidermis after wounding. It also caused microvascular endothelial cells, which restore blood flow, to migrate into the wounded tissue.

The insulin causes these effects by switching on cellular signaling proteins called kinases and a protein called SREBP.

Science Daily December 11, 2006