The autoregulation of the skin microcirculation in healthy subjects and diabetic patients with and without vascular complications.

The skin microvascular autoregulatory capacity was investigated in healthy volunteers and diabetic patients without or with vascular complications. To assess this capacity, skin blood flux (SBF) of different areas was examined during different procedures of venous stasis, standing position, and passive lowering of the leg. SBF was evaluated by laser doppler fluxmetry. There was, in healthy control subjects, the same degree of vasoconstriction, i.e., the same reduction in SBF irrespective of the site of measurement and the procedure used. In diabetic patients, the vasoconstriction elicited in the finger pulp by venous stasis was normal. By contrast, the vasoconstrictor responses to standing or lowering of the leg were impaired. In fact there was, in some patients, an increased SBF instead of a decreased one during standing or lowering of the leg. Impaired vasoconstrictor responses to standing or lowering of the leg was observed even in patients without complications; the impairment, however, was more marked in patients with complications. Thus, the inability of the diabetic skin microvasculature to respond normally to postural changes may be an important factor initiating the development of foot complications. The contribution of local and central reflexes to microvascular autoregulation in diabetic patients and control subjects was also discussed.