Impact of peripheral glucoregulation on memory.

Impaired glucoregulation is associated with neuropsychological deficits, particularly for tests that measure verbal declarative memory performance in older diabetic patients. The performances of 74 undergraduate students (mean age = 21 years) on several verbal declarative measures, including immediate and delayed paragraph recall, verbal free recall, and order reconstruction tasks, were correlated with glucoregulatory indices. The indices were obtained from glucose and insulin levels after a 75-g glucose load. In general, higher blood glucose levels were associated with poorer performance on all memory tests. Glucose ingestion did not interact with performance except on the most difficult task. Subjects with poorer glucoregulation showed higher evoked glucose and insulin, suggestive of a mild glucose intolerance accompanied by mild insulin insensitivity. Results suggest that poor peripheral glucoregulation has an impact on central nervous system functions.