Elevated blood sugar increases the risk of heart disease, not only in people with diabetes but also in those with high-normal readings not considered diabetic. Two new studies provide strong evidence that the increased risk is due to blood sugar itself, independent of other problems that often go along with it, like high blood pressure and cholesterol. Before the studies, diabetes was already known to be bad for the heart: it doubles the risk of dying from cardiovascular disease, and 70 to 80 percent of people with diabetes die from heart attacks, strokes and artery disease. But researchers were not...