Measurement of perception threshold to an electric stimulus using a phase-sensitive technique in normal and diabetic subjects.

To evaluate the functional state of peripheral sensitivity we measured the perception threshold to an electrical stimulus applied deeply at the level of the lower limbs in both diabetic and nondiabetic patients. The data were obtained using a phase-sensitive technique with a sinusoidal applied voltage at 1592 Hz. The test signal applied through needle electrodes was monitored using a current-to-voltage convertor, the current being considered to have two components, one resistive (IR) in phase with the voltage V across the electrodes, and the other capacitive (IC) 90 degrees out of phase. A significantly (p less than 0.001) higher perception threshold was found in diabetic patients than in nondiabetic subjects with all three electrical variables measured: IR, IC and V.