By Paula Spencer, Caring.com senior editorIf skin were merely a sausage casing for the rest of you, it wouldnt be nearly so useful. An organ itself (your bodys largest in terms of both weight and surface area), skin protects against invasive bacteria, regulates body temperature, and picks up information from the stimulation of touch, pressure, pain, heat, and cold. Little wonder, then, that when theres something wrong with you on the inside, your skin sometimes sends up the first warning flare.Diabetes, for example, is generally a silent disease, but it can lead to distinct changes to the skin. So the skin may in fact be the first indicator of whats happening, notes dermatologist Amy Newburger, MD, of Scarsdale, New York, a spokesperson for the American Academy of Dermatology.Heres the skinny on ten dermatologic oddities worth watching for in yourself or someone you love. 1. Red flag: Yellowish skin, orange palms and soles What it means: The cartoonish skin hues of carotenemia can be t...