Relationships between haemostatic factors and capillary morphology in human diabetic neuropathy.

We have examined haemostatic factors in 15 diabetic patients with peripheral neuropathy and 10 diabetic patients without clinical complications. Plasma and blood viscosity, fibrinogen, factor VIIIc, von Willebrand factor activity, spontaneous platelet aggregation and fibrinolytic activity were not significantly different between diabetic patients without clinical complications and diabetic patients with peripheral neuropathy. Platelet aggregation was enhanced in diabetic patients with neuropathy compared with those without complications. In the 15 patients with neuropathy and 3 without complications, who underwent biopsy of sural nerve, skin and muscle, associations were found between haemostatic variables and measures of nerve capillary pathology, notably: plasma fibrinogen and nerve capillary basement membrane thickness (r = 0.70, p < 0.001); thromboxane B2 production and nerve capillary basement membrane thickness (r = -0.61, p < 0.01); plasma fibrinolytic activity and endoneurial capillary lumen size (r = 0.60, p < 0.01) and endothelial cell outer perimeter (r = 0.65, p < 0.01). The main associations of skin and muscle capillary abnormalities were with measures of in vitro platelet aggregation, and the correlations found with nerve capillary measurements were not echoed in the overlying muscle and skin. The results are supportive of the involvement of haemostatic abnormalities in the pathogenesis of diabetic neuropathy.