Rapid modifications of biophysical and biochemical parameters of red blood cell membrane from insulin dependent diabetics after insulin administration.

We have previously shown that red blood cell (RBC) filtrability in uncontrolled insulin dependent diabetics is abnormal compared to healthy subjects, but is corrected by insulin added in vivo or in vitro. We have now found biophysical abnormalities of the RBC membrane in such patients: Fluorescence polarization value (p) evaluated using DPH as probe is significantly lower in patients; insulin added in vitro increases and normalises the p value of diabetic RBC membrane, and has no effect on normal RBC membrane. As there is a relationship between the lipid bilayer and membrane cytoskeleton proteins, this abnormality of RBC membrane fluidity, correctable by insulin, may be an important determinant of the rheological behaviour of the RBC. In parallel, biochemical abnormalities of the RBC membrane are shown in the same patients: Higher cholesterol/phospholipid ratio, lower content in unsaturated fatty acids and higher content in saturated fatty acids. Decreased activity of ouabaine sensitive Na+K+ ATPase and increased activity of Mg++ ATPase. All of these RBC biochemical abnormalities are corrected after 24 h of normoglycaemia obtained by insulin treatment given in vivo with a biostator. Our results show the importance to check the degree of control of glycaemia when studying rheological parameters in diabetes mellitus.