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 act ivation with microcirculation measured by laser-Doppler flowmetry in Type 1 diabetic patients with or without microangiopathy. A total of 44 Type 1 di abetic patients were subdivided into those with (n=24) and without (n=20) m icroangiopathy according to opthalmological findings and the presence or ab sence of microalbuminuria. The control group consisted of 25 healthy people of comparable age, sex, and body mass index. Postocclusive reactive hypere mia (PORH) and thermal hyperemia (TH, at 44 degreesC) were measured at the forearm. Serum N-acetyl-beta -glucosaminidase (NAG) activity, serum E-selec tin, and ICAM-1 concentrations were used as biochemical markers of endothel ial dysfunction. A significantly lower velocity of perfusion increase durin g postocclusive hyperemia (PORHmax.t(1)(-1)) and during thermal hyperemia ( THmax.t(2)(-1)) (P<.01) were accompanied by higher serum NAG activity (20.9 <plus/minus>4.6 vs. 16.3 +/-2.5 U 1(-1), P<.01) in diabetic patients with m icroangiopathy as compared to healthy persons. An inverse relationship was found between PORHmax.t(1)(-1) and NAG (r= -.33) results in diabetic patien ts. In addition, higher mean values of serum NAG activity, E-selectin, and ICAM-1 concentrations were associated with significantly lower values of mi crocirculation parameters (PORHmax.t(2)(-1) and THmax.t(2)(-1)) in six pati ents 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-Dop pler flowmetry in Type 1 diabetic patients as early indicators of vascular changes in very early stage of diabetic Microangiopathy. (C) 2001 Elsevier Science Inc. All rights reserved.