The authors of this report investigated whether higher blood glucose and glycosylated hemoglobin (HbA1c) levels exert a negative impact on memory performance and hippocampal volume and microstructure in healthy, older, nondiabetic individuals without dementia. 141 individuals were studied (mean age 63.1 yr) and memory was tested using the Rey Auditory Verbal Learning Test. Peripheral levels of fasting HbA1c, glucose, and insulin were obtained and correlated with data from 3-tesla MRI scans which assessed hippocampal volume and microstructure. Lower HbA1c and glucose levels were significantly associated with better memory scores in delayed recall and memory consolidation. The authors concluded that even in the absence of type 2 diabetes mellitus or impaired glucose tolerance, chronically elevated blood glucose levels are correlated negatively with cognition function, possibly mediated by structural changes in learning-relevant brain areas. Further studies and clinical trials manipulating glucose levels may be warranted.
Kerti L, Witte AV, Winkler A, Grittner U, Rujescu D, Flöel A: Higher glucose levels associated with lower memory and reduced hippocampal microstructure. Neurology [Epub ahead of print, October 23, 2013].