[Rheologic findings in patients with diabetic retinopathy]

The rheological parameters hematocrit, plasma viscosity, red blood cell aggregation and blood cell rigidity were measured in 256 adult-onset (type II) diabetics. The stage of diabetic retinopathy was graded by means of ophthalmoscopy and videofluorescein angiography. The mean values of hematocrit (men 45 +/- 5%, women 42 +/- 5%) and red blood cell rigidity (1.01 +/- 0.08) were equal to those in normal subjects. Plasma viscosity (1.40 +/- 0.10) mPas, normals: 1.24 +/- 0.05 mPas) and red blood cell aggregation (16.0 +/- 4.2, normals: 14.6 +/- 3.2) were increased over the values in normals. The groups with different stages of diabetic retinopathy showed no difference in all rheological parameters. Plasma viscosity and red blood cell aggregation were determined partly by the levels of the large plasma proteins. In the type II diabetics fibrinogen was the most markedly elevated large plasma protein (4.1 +/- 1.2 g/l, normals: 3.2 +/- 0.6 g/l). Significant correlations were found between plasma viscosity and fibrinogen (0.49); plasma viscosity and alpha-2-macroglobulin (0.33); red blood cell aggregation and alpha-2-macroglobulin (0.28); and red blood cell aggregation and immunoglobulin M (0.25). The elevation of red blood cell aggregation and plasma viscosity may be one of the reasons for disturbed microcirculation and fundus changes in diabetic retinopathy.