A new study links higher blood sugar levels with a higher risk of dementia, even among people who do not have diabetes.
The study, published in the New England Journal of Medicine, found that in people without diabetes, the risk for dementia was 18 percent higher for people with an average glucose level of 115 milligrams per deciliter compared to those with an average glucose level of 100 mg/dl.
In people with diabetes, whose blood sugar levels are generally higher, dementia risk was 40 percent higher for people with an average glucose level of 190 mg/dl compared to those with an average glucose level of 160 mg/dl, according to the researchers.
“The most interesting finding was that every incrementally higher glucose level was associated with a higher risk of dementia in people who did not have diabetes,” said first author Paul K. Crane, MD, MPH, an associate professor of medicine at the University of Washington School of Medicine, adjunct associate professor at the UW School of Public Health, and an affiliate investigator at Group Health Research Institute. “There was no threshold value for lower glucose values where risk leveled off.”
For the study, the researchers used data collected from more than 2,000 Group Health patients age 65 and older in the Adult Changes in Thought (ACT) study.
“One major strength of this research is that it is based on the ACT study, a longitudinal cohort study, where we follow people for many years as they lead their lives,” said senior author Eric B. Larson, MD, MPH, a senior investigator at Group Health Research Institute, who also has appointments at the UW Schools of Medicine and Public Health. “We combine information from people’s research visits every other year with data from their visits to Group Health providers whenever they receive care. And this gave us an average of 17 blood sugar measurements per person — very rich data.”
Measurements included blood glucose (some fasting, some not) and glycated hemoglobin (also known as HbA1c). While blood sugar levels rise and fall in peaks and valleys throughout each day, glycated hemoglobin doesn’t vary as much over short intervals, the researchers explained.
So should people try to eat less sugar to decrease their risk of dementia? Not necessarily, according to Crane.
“Your body turns your food into glucose, so your blood sugar levels depend not only on what you eat but also on your individual metabolism — how your body handles your food,” he said.
He does suggest that taking walks couldn’t hurt. The ACT study previously linked physical activity to later onset and reduced risk of dementia, including Alzheimer’s disease, he noted.
He also emphasized that the latest results come from an observational study.
“What we found was that people with higher levels of glucose had a higher risk of dementia, on average, than did people with lower levels of glucose,” he said. “While that is interesting and important, we have no data to suggest that people who make changes to lower their glucose improve their dementia risk. Those data would have to come from future studies with different study designs.”
More research is planned to delve into various possible mechanisms for the relationship between blood sugar and dementia, he added.
“This work is increasingly relevant, because of the worldwide epidemics of dementia, obesity, and diabetes,” he concluded.
Source: Group Health Research Institute