OBJECTIVE We studied the relationship between vasoconstrictor changes in foot arteries (pedal, metatarsal, and digital arteries) and autonomic neuropathy in diabetic patients to estimate the degrees of sympathetic dysfunction.

RESEARCH DESIGN AND METHODS Sixty-two patients and nineteen age-matched control subjects were studied. The resistance index (RI) and pulsatility index (PI) were measured as vascular hemodynamic parameters using Doppler sonography, and the increases in these hemodynamic parameters (%RI and %PI) from rest to a deep breath were measured as indexes of the degrees of sympathetic vasoconstrictor function. Cardiovascular autonomic function tests (AFTs) were performed and the score was compared to %RI and %PI values obtained.

RESULTS Of the 62 diabetic patients, 51 had various degrees of autonomic neuropathy. Both %RI and %PI in the diabetic patients were significantly < those in the control subjects for all foot arteries tested (all P < 0.001). There were strongly inverse correlations between the %RI and %PI of foot arteries and the AFT score (r = −0.556 to −0.846, P < 0.0001). The %RI of the digital artery was the most strongly correlated with AFT score (r = −0.846, P < 0.0001) among foot arteries tested. The abnormality of sympathetic vasoconstriction was detectable in the majority of the diabetic patients with the early phase of autonomic neuropathy (%RI: 89.5%; %PI: 94.5%).

CONCLUSIONS We conclude that the %RI of the digital artery is a useful and reliable sympathetic function test of early phase in diabetic patients.