Impairment of erythrocyte viscoelasticity is correlated with levels of glycosylated haemoglobin in diabetic patients

Erythrocytes from diabetic patients exhibit impaired viscoelastic propertie s when estimated by various methods. We determined erythrocyte filterabilit y through 5-mum pores, in 51 patients with non-insulin-dependent diabetes m ellitus, 18 healthy controls, 15 patients with homozygous beta -thalassemia and 15 with beta -thalassemia traits. The filtration measurements were mad e with a Hemorheometer, which uses the 'initial flow rate' principle. To de termine the Index of Rigidity (IR) of the red blood cells, we measured the passage time of white blood cell-free erythrocyte suspensions, 8% per volum e, through the filter. Diabetic patients had significantly increased IR in comparison to healthy controls and to patients with beta -thalassemia trait , but not at the level found in patients with homozygous beta -thalassemia. In diabetic patients, a strong correlation between IR and the percentage o f glycosylated haemoglobin was found (r = 0.737, P < 0.0001), and a weaker one with serum unconjugated bilirubin (r = 0.363, P = 0.0097) and serum tot al lipids (r = 0.321, P 0.0286). Patients with severe retinopathy also had significantly increased IR, in comparison to those with or without mild ret inopathy. Anaemic diabetic patients, especially those with the anaemia of c hronic disease, also had significantly increased IR in comparison to non-an aemic diabetics. No correlation between IR, MCV, MCH, MCHC, RDW, RBC morpho logy, serum LDH or the presence of erythrocyte inclusions after incubation with nitrous sodium solution was found. Our findings suggest that glycosyla tion of skeletal proteins probably contributes significantly to the increas ed membrane rigidity of diabetic erythrocytes.