The electrophysiological results in 51 patients with diabetes mellitus type II were compared with those in 30 age and sex matched healthy control subjects. Peripheral and cortical latencies of median and tibial somatosensory evoked potentials (SEP), bilateral I-III and I-V interpeak latencies (IPL) of brainstem auditory evoked potentials (BAEP), bilateral P100 latency of visual evoked potentials (VEP) and bilateral cortical latency and central motor conduction time of motor evoked potentials (MEP) were evaluated. We observed prolonged latencies suggestive of central neuropathy in DM type II. It has been shown that most of the electrophysiological parameters in patients with DM type II correlate with the duration of the disease, some of them with the age of the patient, and few of them with the onset of the disease. To our knowledge, there is no correlation between the electrophysiological parameters and the level of glycemia or the degree of metabolic control. We conclude that central and peripheral neuropathies in DM are related to the duration of the disease and not to the degree of hyperglycemia and metabolic control.