INS and diabetes mellitus: It also significantly improved all tested cognitive functions in the type 1 DM group (with the exception of the escape latency to hidden platform in the first three training blocks) compared to the type 1 group treated with insulin alone and in the type 2 DM group compared to the untreated type 2 diabetic group which indicates a positive effect of blocking NMDA receptors on memory and synaptic plasticity in diabetes.