Wristwatch heart monitors might save your life--and change medicine, too

It begins seven years ago, when my doctor asks me whether I want to lose my foot. I say to him: No, I do not want to lose my foot. "Good," he says back: Monitor your blood sugar, keep it down, and we can manage this disease. Then nobody has to lose a foot. It turns out I have type 2 diabetes, which--from a patient's point of view--boils down to a single data point: the amount of glucose in my bloodstream.