[Erythrocyte aggregation in vivo and diabetic microangiopathy. Physiopathologic determinants and clinical correlations].

Conjunctival angioscopy is a non invasive way for visualization and quantitative evaluation of the microcirculation. Grading red blood cell aggregation is possible in vivo using Ditzel's four grades score. The two-dimensional organization of conjunctival microvessels allows morphometric quantification of microvascular density. The aim of our study was to evaluate the determinant factors of erythrocyte aggregation and the place of conjunctival angioscopy in the early detection of diabetic microangiopathy. Conjunctival parameters were red blood cell aggregation (Ditzel's score) and morphometric evaluation of capillary, venular and arteriolar density. Criteria of diabetic microangiopathy were microalbuminuria and retinal fluorescein angiogram. Both conjunctival angioscopy and retinal angiogram were scored independently. Results obtained in 30 type 1 diabetic patients, with multifactorial statistical analysis, show that red blood cell aggregation in vivo is an essential discriminant factor for diabetic retinopathy and nephropathy. This rheological phenomenon depends more on duration of diabetes (analysis of variance p = .0005, r = .65) and metabolic control than on albuminemia or fibrinogenemia such as in non-diabetic patients. Manual morphometric data confirmed vascular rarefaction associated with excessive red blood cell aggregation (beta = .50). These results suggest that grading red blood cell aggregation in vivo is an interesting tool for physiopathological and clinical studies of diabetic microangiopathy.