Increased erythrocyte aggregation in diabetes mellitus and its relationship to glycosylated haemoglobin and retinopathy.

The velocity of erythrocyte aggregation in vitro was determined in 15 non-diabetic and 28 Type 1 (insulin-dependent) diabetic subjects, in autologous plasma under uniform shear flow using a rheoscope combined with a television image analyzer and a computer. In the diabetic subjects, the velocity of aggregation showed a significant correlation with the haemoglobin A1 level, and was significantly increased in the proliferative retinopathy group. An alteration of plasma protein composition in the diabetic subjects (increase of phi- and alpha 2-fractions) also influenced erythrocyte aggregation, being related to the haemoglobin A1 level. The percentage of the phi-fraction and a parameter, (alpha 2 + phi)/albumin, defined by plasma electrophoresis, showed a strong correlation with the velocity of aggregation.