Based upon clinical experience, peripheral nerve stimulation for neuromuscular monitoring under general anesthesia sometimes seems to be difficult in patients with diabetes mellitus. The aim of this study was to evaluate the applicability of the evoked electromyogram (EMG) in diabetics compared to non-diabetic controls.109 ophthalmosurgical patients (35 diabetics, 74 non-diabetics) were investigated. Relaxometry was performed by electrical stimulation of the ulnar nerve proximal of the wrist and the evoked EMG was recorded above the hypothenar muscle (Relaxograph, supplied by Datex). Immediately after induction of anaesthesia the calibration of the device was performed.The calibration of the relaxograph could be performed successfully only in 57.1% of the diabetics compared to 93.2% of the non-diabetics (p < 0.001). Consequently the uncalibrated mode had to be chosen more often in diabetics than in non-diabetics. In two non-diabetics and three diabetics no stimulation response could be achieved. Biometrical data, serum electrolyte concentrations, wrist circumference and body temperature were similar in both groups. The calibration mode could be performed in diabetics without peripheral polyneuropathy more often (76.5%) than in diabetics with peripheral polyneuropathy (38.9%) (p < 0.05).The results show that the applicability of the peripheral nerve stimulator in diabetic patients is more difficult than in non-diabetics. The disturbances of the peripheral nervous system seem to be responsible for these problems.