1. In two groups of diabetic patients, one with and one without signs of peripheral neuropathy, reflex short vasoconstrictor responses to such stimuli as a cough, a sharp inspiration or sudden noise were recorded from a finger and both big toes by volume plethysmography. Simultaneous electrodermal responses to the same stimuli were recorded from a hand and a foot. Vasodilator responses to body warming were also recorded.
2. Significant impairment of these vasomotor reflexes in diabetic patients with neuropathy indicates that the sympathetic vasomotor system can be involved in diabetic peripheral neuropathy.
3. Loss of the reflex electrodermal responses is also evidence of impairment of another sympathetic function in such patients.
4. Because stimuli vary in their effectiveness in causing responses in both groups of subjects, it is suggested that changes of central nervous conductivity also occur in diabetes.