Correlations between the severity of retinopathy in diabetic patients and whole blood and plasma viscosity

The aim of this study was to correlate the severity of retinopathy in diabetic patients with the whole blood and plasma viscosity. The studies were performed on 52 patients suffering from type II diabetes mellitus with non-proliferative retinopathy (25 men and 27 females, mean age of patients 64+/-6.5 years). The mean duration of diabetes treatment was 13.7 years. The control group consisted of 43 healthy persons (20 men and 23 women, the mean age of controls was 55.9+/-9.2 years). Blood samples were taken from patients immediately after ophthalmological examination from anticubital vein and anticoagulated with K2EDTA. The symptoms of retinopathy were: macular edemas, microaneurysms, hard and soft exudates and hemorrhagic focuses. The severity of particular signs of retinopathy was expressed in a three point scale. The total number of rank points was correlated with blood and plasma viscosity, moreover with eyes acuity. Blood viscosity measurements were performed with the use of cone-plate Brookfield's viscometer at shear rate 150 s(-1), and plasma viscosity with capillary Ubbelohd's viscometer. Besides the viscometric examinations hematocrit, fibrinogen, blood morphology, total cholesterol concentration, LDL-cholesterol, HDL-cholesterol, triglycerides, blood glucose concentration and glycosylated hemoglobin were examined. The whole blood viscosity, the corrected blood viscosity adjusted to 45% of hematocrit were significantly higher in diabetics (p<0.001). The whole blood relative viscosity was also significantly elevated in diabetic patients (p<0.002). The correlation between visual acuity and rank point of retinopathy severity was negative (r= -0.91, p<0.001). The retinopathy severity was positively correlated with whole blood and plasma viscosity (r=0.51; p<0.001 and r=0.4; p<0.005, respectively).

Elevated blood and plasma viscosity may play an additional and significant role in the development of diabetic retinopathy.