There are many reasons to keep your blood sugar under control: protecting your arteries and nerves are two of them. Here’s another biggie: preventing dementia, the loss of memory and thinking skills that afflicts millions of older Americans. A study published today in the New England Journal of Medicine shows that even in people without diabetes, above normal blood sugar is associated with an increased risk of developing dementia. The study does not prove that high blood sugar causes dementia, only that there is an association between the two. For that reason, don’t start trying to lower your blood sugar simply to preserve your thinking skills, cautions Dr. Nathan. There’s no evidence that strategy will work, although he says it should be studied. But it is still worth keeping an eye on your blood sugar. Excess blood sugar can lead to diabetes and a variety of other health problems, including heart, eye, kidney, and nerve disease.