Influence of D- and L-glucose on erythrocytes and blood viscosity

Elevated blood glucose levels are associated with substantial morbidity and mortality. The pathomechanism behind it is not well understood. The aim of the present study was to investigate the effect of glucose on blood rheology.

Blood from healthy volunteers was incubated with various concentrations of D- and L-glucose for 1 h at 37 degrees C. Whole blood viscosity at haematocrit 45% was measured at high and low shear rate (94.5 and 0.1 s(-1)). Erythrocyte shape and volume were assessed. Haemoglobin solutions were incubated with D-glucose for up to 96 h and the viscosity was measured.

D-glucose dissolved in H2O and diluted with isotonic NaCl, added to whole blood (additional D-glucose concentrations 0-80 mM), led to a red cell swelling and an increase in blood viscosity at low shear rate (0.1 s(-1)). This process was reversible upon removal of D-glucose. L-glucose, which is not transported into the red cell by the D-glucose-specific transport protein GLUT-1, had no effect. When D-glucose was dissolved and diluted in autologous plasma, haematocrit and viscosity remained unaffected, but L-glucose decreased both values. Incubation of a haemoglobin solution with D-glucose at 37 degrees C led to a time-dependent increase in glycosylated haemoglobin (HbA1C) up to 8%, but left the viscosity unchanged.

Blood glucose tested in a wide range of concentrations did not affect blood viscosity and morphological or biophysical properties of erythrocytes.