Filtration of dilute erythrocyte suspension as a measure of erythrocyte deformability and its relationship to blood glucose control in diabetes mellitus

The filtration of dilute erythrocyte suspension over 5 micron polycarbonate filters was examined as a measure of erythrocyte deformability in 20 insulin requiring diabetic patients and related to glycaemic control as assessed by fasting whole blood glucose and HbAlc. Twelve patients were reassessed after a period of improved glycaemic control. No relationship was found between filterability and whole blood glucose and HbAlc but there was a highly significant relationship p < 0.001 between the calculated residual leucocyte count of the erythrocyte suspensi on and filterability. The change in erythrocyte suspension filterability following a period of improved diabetic control was also dependent on the concentration of contaminating leucocytes present on each occasion p < 0.05, and bore no relationship to improvement in diabetic control. Gross alterations of the erythrocyte concentration did not affect this linear relationship between the leucocyte concentration and pressure generated on filtration in either a normal or a diabetic subject. In both normal and diabetic subjects the leucocyte appears to be the major determinant of filterability in this low pressure filtration system.