Reduced hyperaemic response under the diabetic neuropathic foot

Diabetic neuropathic ulcers typically occur at high pressure sites. Microvascular blood flow has been assessed on the plantar surface of the foot in three matched groups each of 12 subjects free from macrovascular disease: (a) patients with diabetic neuropathy with abnormal foot pressures and previous neuropathic ulceration; (b) non-neuropathic diabetic patients; (c) non-diabetic control subjects. Resting flow was measured at the highest pressure point under the metatarsal heads (defined by pedobarograph) using laser doppler flowmetry, and the hyperaemic response was assessed at the same site following 3 min standing. Peak flow was significantly reduced in neuropathic patients (2.3 +/- 1.4 (SD) volts) compared with control subjects (4.0 +/- 2.0 volts; p less than 0.03). The time for blood flow return to baseline was significantly prolonged in neuropaths (159 +/- 72 s) compared with normal subjects (93 +/- 18 s; p less than 0.01), with a significant delay also seen in non-neuropaths (151 +/- 38 s; p less than 0.0001 compared with normal).