High Blood Sugar in Healthy Adults Linked to Reduced Brain Activity: Study Finds - Video

A study by Baycrest found that high blood sugar may impair brain health even in people without diabetes.

"Our results show that even if someone does not have a diabetes diagnosis, their blood sugar may already be high enough to be negatively impacting their brain health,” said Dr. Jean Chen, senior author on the study and Senior Scientist at the Rotman Research Institute, part of the Baycrest Academy for Research and Education (BARE). “Blood sugar exists on a spectrum – it isn’t a black and white categorization of healthy or unhealthy."

The study, titled “The associations among glycemic control, heart variability, and autonomic brain 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 and older. For each individual, researchers analyzed blood sugar, brain activity using magnetic resonance imaging (MRI) scans and heart rate variability through electrocardiogram (

ECG) readings.

Main study findings were:

Higher blood sugar was associated with decreased connection 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 it was present across all ages; older adults generally had higher blood sugar than younger adults.

The effect was also stronger in women than in men.

In addition, there was a link between higher blood sugar and lower heart rate variability – that is, the beat-to-beat change in an individual’s heart rate. Previous research indicates that higher heart-rate variability is associated with better brain health.

Reference: Jeffrey, X. Y., Hussein, A., Mah, L., & Chen, J. J. (2024). The associations among glycemic control, heart variability, and autonomic brain function in healthy individuals: Age-and sex-related differences. Neurobiology of Aging, 142, 41-51.