Comparison of Laser-Doppler Flowmetry with Biochemical Indicators of Endothelial Dysfunction Related to Early Microangiopathy in Type 1 Diabetic Patients

The aim of this study was to compare biochemical markers of endothelial activation with microcirculation measured by laser-Doppler flowmetry in Type 1 diabetic patients with or without microangiopathy. A total of 44 Type 1 diabetic patients were subdivided into those with (n=24) and without (n=20) microangiopathy according to ophthalmological findings and the presence or absence of microalbuminuria. The control group consisted of 25 healthy people of comparable age, sex, and body mass index. Postocclusive reactive hyperemia (PORH) and thermal hyperemia (TH, at 44 degrees C) were measured at the forearm. Serum N-acetyl-beta-glucosaminidase (NAG) activity, serum E-selectin, and ICAM-1 concentrations were used as biochemical markers of endothelial dysfunction. A significantly lower velocity of perfusion increase during postocclusive hyperemia (PORH(max) x t(1)(-1)) and during thermal hyperemia (TH(max) x t(2)(-1)) (P<.01) were accompanied by higher serum NAG activity (20.9+/-4.6 vs. 16.3+/-2.5 U l(-1), P<.01) in diabetic patients with microangiopathy as compared to healthy persons. An inverse relationship was found between PORH(max) x t(1)(-1) and NAG (r=-.33) results in diabetic patients. In addition, higher mean values of serum NAG activity, E-selectin, and ICAM-1 concentrations were associated with significantly lower values of microcirculation parameters (PORH(max) x t(2)(-1) and TH(max) x t(2)(-1)) in six patients without microangiopathy who had at least one of the above biochemical markers higher than mean+2 S.D. range. We suggest that serum NAG activity, E-selectin, and ICAM-1 concentrations may be used together with laser-Doppler flowmetry in Type 1 diabetic patients as early indicators of vascular changes in very early stage of diabetic microangiopathy.