Correlations between PFC activation, as reflected by changes in oxyhemoglobin (oxy-Hb) concentration and cognitive outcomes were analyzed.<h4>Results</h4>The participants of the ED group were older than those in the non-ED group, and had a higher incidence of type 2 diabetes mellitus than those in the non-ED group. This evidence concerns the gene GSTM1 and type 2 diabetes mellitus.