The means by which insulin triggers acne formation is beginning to yield to the light of day. Insulin stimulates the release of a hormone called insulin-like growth factor-I, or IGF-I, within the skin. IGF-1, in turn, stimulates tissue growth in hair follicles and in the dermis, the layer of skin just beneath the surface.9 Insulin and IGF-1 also stimulate the production of sebum, the oily protective film produced by the sebaceous glands.10 Overproduction of sebum, along with skin tissue growth, leads to the characteristic upward-growing reddened pimple.
