Effects of hyperglycaemia and sorbitol accumulation on erythrocyte deformability in diabetes mellitus D BAREFORD, * PE JENNINGS,t PCW STONE, * S BAAR, * AH BARNETT,t

SUMMARY Erythrocyte deformability was studied in a total of 83 poorly controlled diabetics (mean blood glucose 12-2 mmol/l) who were divided into three groups, each with matched healthy controls. There was no appreciable difference between diabetics and matched controls regarding the filtration of erythrocytes through 3 gum diameter straight channel pores (25 diabetics) or tortuous channel pores (28 diabetics), or for the measurement of erythrocyte elongation over a range of osmolalities in the Ektacytometer (30 diabetics). When erythrocytes from 17 additional diabetics and 17 healthy controls were incubated for two hours at 37°C in hyperglycaemic (50 mmol glucose/l) buffer, how-ever, there was a considerable reduction in erythrocyte filterability for both diabetics and controls in parallel with an increase in erythrocyte sorbitol concentration. This loss of filterability was prevented by the addition of an aldose reductase inhibitor (Sorbinil). High glucose concentrations (- 50 mmol/l) impair the filterability of erythrocytes through 3 gm pores, and the intracellular accumulation of sorbitol in poorly controlled outpatients is therefore unlikely to have a major adverse effect on erythrocyte rheology in diabetes mellitus. Erythrocytes from uncontrolled diabetics were orig-inally found to have impaired deformability whe