Impaired erythrocyte doublet formation in diabetes.

A new means by which to examine erythrocyte deformability, the rate at which erythrocytes in dilute suspension form doublets after settling to the surface of a microscope slide, has been developed and tested. Doublet formation consists of the evaluation and subsequent apposition of one cell over another, a process limited by the ability of each red cell membrane to bend. The cell-cell attraction that promotes doublet formation is controlled by adding an appropriate amount of dextran to the artificial suspending medium. Videotaping permits careful analysis of doublet formation rate and maintains a permanent record. When erythrocytes from 20 diabetic and 20 non-diabetic subjects were studied, doublet formation rates were found to be strikingly different. Cells from half of the diabetics studied formed less than three doublets in 20 min while the non-diabetic mean for the same period was 15 doublets. No overall correlation between doublet formation and fasting glucose could be found. No relation between doublet formation rate and type of diabetes, treatment, or microvascular complications was observed. Doublet formation rate is a simple and rapid means of detecting and studying reduced erythrocyte deformability in diabetes.