The influence of isolated small nerve fibre dysfunction on microvascular control in patients with diabetes mellitus.

The aim of the study was to investigate the influence of isolated small nerve fibre dysfunction on microvascular skin blood flow and transcutaneous oxygen tension in patients with diabetes mellitus. Small nerve fibre dysfunction was assessed by the measurement of thermal and pain perception thresholds. Patients with evidence of large fibre disturbances as evaluated by means of vibration perception threshold were excluded from the study. Microvascular blood flow was investigated with laser-Doppler-fluxmetry (LDF) following stimulation with acetylcholine and mild thermal injury. Diabetic patients with small nerve fibre injury showed a significantly reduced increase in the laser-Doppler-flux signal following the application of acetylcholine compared with patients without neuropathy or healthy control subjects (2.8 arbitrary units (AU) (1.3-5.5) vs. 7.2 AU (4.1-25.5); P = 0.007 and vs. 8.5 AU (3.0-17.0), P = 0.02, respectively). The increase in LDF following thermal injury was also diminished in patients with small nerve fibre dysfunction compared with patients without neuropathy or the control group (29.8 AU (17.2-46.5) vs. 51.2 AU (29.5-93.5); P = 0.02 and vs. 54.6 AU (39.7-97.7); P = 0.004, respectively). In addition, they showed a significantly reduced transcutaneous oxygen tension compared with the other groups (42.9 mmHg (41.6-55.5) vs. 56.1 mmHg (49.2-60.8); P = 0.04 and vs. 59.0 mmHg (54.6-80.3), P = 0.03, respectively). Our study confirms an association between small nerve fibre injury and skin microvascular dysfunction. It further underlines the concept of neurovascular disturbances in the pathogenesis of neurotrophic foot ulceration. Diabet. Med. 18, 489-494 (2001)