"I'm afraid there's a growing sense that the path to health is through testing," says Dr. H. Gilbert Welch, a Dartmouth Institute internist who has written books on the pitfalls of overdiagnosis. Encouraging the worried well to order their own blood tests feeds that mindset, he says. TEK Image/Science Photo Library/Getty Images hide caption

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Geneticists found clues to a disease of iron storage in the remains of several Bronze Age inhabitants of what's now Rathlin Island in Northern Ireland. Chrisgel Ryan Cruz/Flickr hide caption

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The Centers for Disease Control and Prevention estimates that 86 million Americans over age 20 have abnormal blood sugar levels. Over the long run, that can seriously damage the eyes, nerves, kidneys and blood vessels. iStockphoto hide caption

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