Higher blood-sugar levels, even those well short of diabetes, seem to raise the risk of developing dementia, a major new study finds. Researchers say it suggests a novel way to try to prevent Alzheimer’s disease — by keeping glucose at a healthy level.
Alzheimer’s is by far the most common form of dementia and it’s long been known that diabetes makes it more likely. The new study tracked blood sugar over time in all sorts of people — with and without diabetes — to see how it affects risk for the mind-robbing disease.
The results challenge current thinking by showing that it’s not just the high glucose levels of diabetes that are a concern, said the study’s leader, Dr. Paul Crane of the University of Washington in Seattle.
“It’s a nice, clean pattern” — risk rises as blood sugar does, said Dallas Anderson, a scientist at the National Institute on Aging, the federal agency that paid for the study.
Because so many attempts to develop effective drugs have failed, “It looks like, at the moment, sort of our best bet,” Anderson said. “We have to do something. If we just do nothing and wait around till there’s some kind of cocktail of pills, we could be waiting a long time.”
About 35 million people worldwide have dementia; in the United States, about 5 million have Alzheimer’s disease. What causes it isn’t known. Current treatments just temporarily ease symptoms. People who have diabetes don’t make enough insulin, or their bodies don’t use insulin well, to turn food into energy. That causes sugar in the blood to rise, which can damage the kidneys and other organs.
The new study, published in the New England Journal of Medicine, just tracked people and did not test whether lowering someone’s blood sugar would help treat or prevent dementia.
“We don’t know from a study like this whether bringing down the glucose level will prevent or somehow modify dementia,” but it’s always a good idea to avoid developing diabetes, he said.
Eating well, exercising and controlling weight all help to keep blood sugar in line.
The study involved 2,067 people 65 and older Seattle. At the start, 232 participants had diabetes; the rest did not. After nearly seven years of follow-up, 524, or one quarter of them, had developed dementia — mostly Alzheimer’s disease. Among participants who started out without diabetes, those with higher glucose levels over the previous five years had an 18 percent greater risk of developing dementia than those with lower glucose levels.
Among participants with diabetes at the outset, those with higher blood sugar were 40 percent more likely to develop dementia than diabetics at the lower end of the glucose spectrum.
The effect of blood sugar on dementia risk was seen even when researchers took into account whether participants had the apoE4 gene, which raises the risk for Alzheimer’s.