High blood sugar impairs brain health even without diabetes

A Baycrest study found that high blood sugar can harm brain health, even in people without diabetes. While the link between blood sugar levels and brain health is well documented in people with diabetes, Baycrest is the first to investigate this connection in people without this diagnosis.

Our results show that even if someone doesn’t have a diabetes diagnosis, their blood sugar levels can already be high enough to negatively impact their brain health. Blood sugar is on a spectrum – it is not a black and white categorization of healthy or unhealthy.”

Dr. Jean Chen, senior author of the study and senior scientist at the Rotman Research Institute, part of the Baycrest Academy for Research and Education (BARE)

The study, titled “The associations between glycemic control, cardiac variability, and brain autonomic function in healthy individuals: age- and sex-related differences,” was recently published in the journal Neurobiology of aging and examined 146 healthy adults aged 18 years and older. For each individual, researchers analyzed blood sugar levels, brain activity using magnetic resonance imaging (MRI) scans and heart rate variability via electrocardiogram (ECG) measurements.

“The findings highlight the importance of controlling your blood sugar levels through healthy diet and exercise, not only for your body but also for your brain,” said Dr. Chen, who is also Baycrest’s Canada Research Chair in Neuroimaging of Aging and professor of biomedical physics . at the University of Toronto. “It is also important to get regular checkups and work with a healthcare provider, especially if you have been diagnosed with pre-diabetes.

Main research results

• Higher blood sugar levels were associated with reduced connectivity in brain networks. These networks play a crucial role in all aspects of cognition, including memory, attention and emotion regulation.
• The effect was stronger in older adults, but was present at all ages; older adults generally had higher blood sugar levels than younger adults.
• The effect was also stronger in women than in men.
• Additionally, there was a link between higher blood sugar levels and lower heart rate variability, that is, the beat-to-beat change in an individual’s heart rate. Previous research shows that higher heart rate variability is associated with better brain health.

In future work, the researchers could further explore how to improve brain function by changing heart rate variability, which is an easier target for intervention than blood sugar levels, especially in non-diabetic individuals.

This study was conducted using data from the Leipzig Study for Mind-Body-Emotion Interactions (LEMON) dataset. It was funded by the Canadian Institutes of Health Research and the Natural Sciences and Engineering Research Council of Canada.