High levels of blood sugar boost risk of dementia, study finds

High levels of blood sugar raise the risk of dementia, even if a person doesn’t have diabetes, a condition known to be associated with the brain disease, a study found.

The higher the level of blood sugar among patients, the greater the risk of dementia, according to the report published in the New England Journal of Medicine. The finding was also true of diabetes patients.

Previous research has found that diabetes diagnosed later in life conveys a high risk of dementia. Insulin doesn’t work properly in the brains of those with Alzheimer’s disease, the most common form of dementia, leading researchers to explore whether GlaxoSmithKline Plc’s diabetes drug Avandia may benefit those with the ailment. Clinical trials found the drug didn’t help.

“It’s a steadily increasing risk, the higher the blood glucose, the higher the risk, and that’s one of the things that surprised us,” Paul Crane, a study author and associate professor of medicine at the University of Washington in Seattle, said in a telephone interview.

It’s not clear why blood sugar is associated with dementia risk, Crane said. Higher levels of blood sugar may play a role in vascular disease or inflammation. Little research has been done on the effects of blood sugar within the normal range, he said.

The research analyzed the medical records of about 2,100 people who were part of the Adult Changes in Thought study. The study, begun in 1994, follows adults older than age 65. Participants are evaluated every two years by researchers.

More than 5 million people in the U.S. have Alzheimer’s, a progressive disease that erodes a patient’s memory, thinking and ability to carry out simple tasks. The cause of the illness is unknown, and there is no known cure.