Effect of ischemia on peripheral nerve function in diabetes mellitus

In Japan, diabetic patients are known to be able to sit on the floor for a prolonged time because of mildness or absence of ischemic paresthesia. In order to investigate this resistance to ischemia quantitatively, the mixed nerve function of the median nerve was studied during 30 min of ischemia using surface electrodes in 60 diabetic patients and 15 normal subjects. In studies of 33 unequivocal diabetics, potential amplitudes decreased during ischemia more slowly than in the controls, and at 15 min of ischemia, potential amplitudes were greater in all 33 diabetics than in the 15 normal subjects. The relationship between the resistance to ischemia and various aspects of diabetes was studied further in the 60 diabetics including the 33 aforementioned patients. Resistance to ischemia was found in almost all diabetics and no significant correlation was shown with values for fasting blood glucose and HbA1c, other diabetic complications or duration of diabetes. However, values for potential amplitudes declined to the normal range in seven of 18 patients after strict glucose control. These results suggest that resistance to ischemia is the earliest manifestation of peripheral nerve dysfunction and is different from classical diabetic neuropathy. Furthermore, the method employed in this study is simple, noninvasive and clinically very useful.