Patients with heightened blood sugar levels—even those who do not have diabetes—are more likely to develop dementia than patients with lower levels, according to a study published in NEJM this week.
The study findings challenge existing thinking by proving that high glucose levels can have a negative effect on health without triggering diabetes, according to lead author Paul Crane of the University of Washington.
For the study, researchers analyzed the medical records of about 2,067 adults who participated in the Adult Changes in Thought
study, which began in 1994 and monitors the health of thousands of patients over age 65. At the start, all participants were dementia-free, and 232 participants had diabetes.
Seven years later, about 25% of the participants had developed dementia, and most of those participants had suspected cases of Alzheimer's disease.
Washington researchers used the data to deduce that diabetes-free participants who had above average blood glucose levels were 18% more likely to develop dementia than those who had average blood glucose levels.
Among patients with diabetes, those with blood sugar levels of 190 milligrams per deciliter were 40% more likely to develop dementia that those with 30 fewer milligrams per deciliter.
"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," Crane said.
However, Crane cautioned that "the magnitude of risk for any individual is low. I don't want anyone to read this and get alarmed," Crane said, adding that the study "shows that what we had thought was normal for blood sugar is appropriate for the heart and the kidney, but the brain seems to have a different idea. There is no threshold where you're safe from dementia."
Researchers were unable to explain why blood sugar is associated with dementia risk, Crane said (Lopatto, Bloomberg News, 8/8; Marchione, AP/Philadelphia Inquirer, 8/7; Emery, Reuters, 8/8).
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