Summary. The aim of this study was to investigate patients with non-insulin dependent diabetes by laser Doppler flowmetry in order to assess changes in the peripheral flow regulation during hemodynamic tests as evidence of the impaired auto-regulation of the microcirculation. Two groups of subjects were included in the study. The first group included 12 dia- betic patients with electromyographical signs of neuropathy and without peripheral arterial occlusive disease, while the sec- ond (control) group included 12 healthy subjects. Microcirculation investigations were carried out at rest and after hemodynamic tests. Blood flow was measured using a laser Doppler flowmetry. Changes in the flow minus the »biological zero« value were measured after 3 minutes of artificial arterial occlusion, after deep inspiration and by experimental venous hypertension (40 and 70 mm Hg), which was used to provoke the venoarteriolar reflex. The resting flow was significantly higher in diabetic patients compared to the healthy subjects (p<0.01). The vasoconstrictor response to the deep inspiration and experimental venous hypertension, cuff pressure 40 mm Hg, was significantly impaired in diabetic patients as compared to the healthy subjects (p<0.001 vs. p<0.05). The maximal hyperemia after artificial arterial occlusion was significantly re- duced in diabetic patients in comparison with the healthy controls (p<0.01). Laser Doppler flowmetry provides a non-invasive means for evaluating microcirculating disturbances in diabetes, long before the initial clinical presentation of peripheral arterial occlusive disease or diabetic foot.