Background. Early stages of diabetic microangiopathy are accompanied with dysfunction, manifested by changes of some biochemical parameters. Parallel changes were observed in microcirculation. The aim of this study was to compare microcirculation in the skin of a forearm evaluated by laser Doppler with selected laboratory markers of endothelial dysfunction in Type 1 diabetes mellitus without microangiopathy or with incipient microangiopathy.
Methods and Results. Group of 43 Type 1 diabetic patients was examined in this study. 20 of them had no signs of microangiopathy and in 23 patients a simple diabetic retinopathy (background retinopathy) was diagnosed. Control group consisted of 25 healthy persons of comparable age, sex, and body mass index. All persons involved in this study were examined by laser Doppler and by biochemical examination and the results were compared. In comparison with control group, in diabetic patients the arm occlusion significantly lowered the increase of perfusion (29±12 vs. 41±18 perfusion units (PU) p<0.01). Similarly the perfusion velocity increase was significantly lower in diabetic patients than in healthy controls (p<0.01). Also the velocity of the perfusion increase after the warming up was lower in the diabetic than in non-diabetic persons (p<0.01). Such changes of perfusion or those of velocity of perfusion increase were significantly lower in diabetic patients with microangiopathy than in those without this complication. Perfusion increases after both stimuli highly correlated (r=0,86, p<0.001). In diabetic patients with microangiopathy significantly higher N-acetyl-b-glucosaminidase (NAG) activities in serum and E-selection or ICAM-1 concentrations were found as compared with patients without microangiopathy, whereas plasma concentrations of tissue plasminogen activator (tPA) or inhibitor (PAI-1) were comparable with those in the control group. NAG activity inversely correlated with velocity of the perfusion increase after both the occlusion (r= -0.41, p<0.01) and the warming (r= -0.38, p<0,05). Similar relationship was found between tPA or E-selectin and the velocity of the perfusion increase after the occlusion (r= -0.48, p<0.01).
Conclusions. Our results confirm that biochemical parameters and microcirculation are impaired in the early stage of microangiopathy in Type 1 diabetic patients. Detailed analysis showed that both types of examination offer slightly different information on the vascular status. A long prospective study in diabetic patients without incipient vascular changes will be necessary to evaluate if biochemical or microcirculatory changes can bring an earlier information on the developing angiopathy.
microangiopathy, Type 1 diabetes mellitus, microcirculation, endothelial dysfunction.