Glucose is the only fuel normally used by the brain. It is thought that blood glucose levels affect cognitive function. The present study investigated whether performance in the emotional Stroop task (EST), which can evaluate both the cognitive function and emotional state of subjects, was susceptible to blood glucose levels or not. Each subject participated in the EST under both fasting condition (FC) and blood glucose increased condition (BGC). Our results show that the reaction time of the EST in the BGC was significantly higher than that in the FC (p = 0.0011). However, we did not find a significant difference in emotional state between BGC and FC (p = 0.5134). From these results, we conclude that increased blood glucose levels improve cognitive function but does not change the emotional state of subjects.
