Evaluation of skin vasomotor reflexes in response to deep inspiration in diabetic patients by laser Doppler flowmetry - A new approach to the diagnosis of diabetic peripheral autonomic neuropathy

OBJECTIVE - To evaluate the peripheral sympathetic function in feet of NIDDM patients by means of laser Doppler flowmetry. RESEARCH DESIGN AND METHODS - After deep inspiration, we measured the vasoconstrictor response in the feet of 51 patients with NIDDM, as compared with those of 20 healthy control subjects, using laser Doppler flowmetry. Subjects whose skin temperature was <32 degrees C were excluded from our study because a skin temperature of similar to 34 degrees C is the optimal temperature for the evaluation of skin vasomotor reflexes in response to a deep inspiration by laser Doppler flowmetry. RESULTS - The vasoconstrictor response to deep inspiration in the big toe was significantly decreased in NIDDM patients compared with healthy subjects (26.8 +/- 20.0 vs. 48.3 +/- 18.5%, P < 0.0001). In NIDDM patients, the vasoconstrictor response was positively correlated with the duration of diabetes, the median motor and sensory nerve conduction velocities, the coefficient of variation of the R-R interval at rest, and the postural fall in systolic blood pressure. The vasoconstriction was inversely correlated with the vibratory perception threshold. CONCLUSIONS - Vasomotor reflexes in the lower limbs were markedly impaired in NIDDM patients. The measurement of vasoconstrictor responses to deep inspiration by using laser Doppler flowmetry is a novel and useful method for detecting peripheral sympathetic failure in diabetic patients.