Researchers from four universities report in the Annals of Neurology that people who absorb glucose more slowly than those who metabolize it quickly are more forgetful and are more likely to have a faulty dentate gyrus, a pocket in the hippocampus section of the brain. The hippocampus is involved with learning and memory formation. 

The findings were based on glucose testing, memory evaluations and fMRI scans of the brains of 240 healthy people ages 65 and older without dementia, and applied even in those without diabetes, which is characterized by an inability to readily convert sugar into energy.