Is impaired red cell filtration in diabetics due to a small abnormal sub-population of cells?

Differences in filtration between RBC's from diabetics and normal subjects were readily detected with nickel filters but not using polycarbonate filters. Parallel measurements using the CTTA demonstrated that although the mean transit time of diabetic and normal cells was similar the more rigid cells within the samples from diabetics were significantly less deformable. This suggests that the abnormalities detected by nickel filters were due to a sub-population of less deformable cells rather than an abnormality of diabetic cells as a whole. In a further study where increasing numbers of glutaraldehyde hardened cells were added to normal red cell samples the CTTA instrument showed that 10% of hardened cells could be detected without any change being shown in the mean transit time. At this level the nickel filter was much more sensitive than the Nucleopore filter at detecting the sub-population of hardened cells. Taken together these data support the hypothesis that diabetics have a small circulating sub-population of rigid red cells that can be readily detected using nickel filters.