Assessment of 16 young men with insulin-dependent diabetes mellitus was undertaken with neuropsychological measures of attention, decision-making, and motor tasks. Those patients in very good, or near-normal, blood glucose control demonstrated decreased attention on visual and auditory simple reaction-time tasks, compared with those in moderate blood glucose control. Patient groups did not differ in their decision-making performance; nor did they differ in motor skill performance. These results replicate earlier findings of differences in visual attention in groups of patients according to degree of blood glucose control and show between-group differences with an auditory reaction time measure. The results suggest that patients with near-normal blood glucose control may exhibit slowed simple attention, whether information presentation is visual or aural.