Sensitive detection of hemodynamic failure during orthostatic stress in patients with diabetic polyneuropathy using a mini laser Doppler blood flowmeter

Autonomic dysfunction in diabetes is serious but often underestimated. The purpose of this study was to evaluate hemodynamics within the important initial phase just after standing, which cannot be evaluated by conventional instruments for orthostatic hypotension. Earlobe blood flow (EBF), which indirectly reflects the blood pressure response on standing, was evaluated using a mini laser Doppler flowmeter during standing from the sitting position in 58 healthy controls and 56 diabetic patients categorized as without (11), mild (27), and advanced diabetic polyneuropathy (18). The response area of the EBF waveform within 30 seconds after standing was calculated. An increased response area indicates poor recovery of EBF. Response area increased significantly with the degree of neuropathy (P < .001 for linear trend). Orthostatic hypotension was detected in two patients in the mild neuropathy group. The present approach may be sensitive and practical for detecting autonomic dysfunction not detected with the conventional orthostatic test.