Erythrocyte rheological changes in obese patients: influence of hyperinsulinism.

Objective: To investigate the rheological properties of RBC in obese subjects and the factors associated with their changes.
Subjects: Two consecutive studies of non diabetic obese subjects.
Measurements: Filtration index of RBC using the Hanss hemorheometer, RBC filterability using a cell transit time analyser and RBC aggregation measured on the Myrenne aggregometer.
Results: In both studies an increase in the filtration index of RBC, namely a reduction in their deformability, was found. In the first study the filtration index correlated negatively with hematocrit and positively with plasma C peptide levels. In the second study RBC filterability was also studied by the cell transit time analyzer in which there is no aggregate formation. The RBC transit time was not found to be different in the obese patients and in the controls, but RBC aggregation was increased and correlated significantly with body weight and BMI. RBC aggregation worsened after four days of hypocaloric diet.
Conclusion: (1) obesity, independently of the other cardiovascular risk factors, is associated with significant changes in RBC rheology; (2) these changes are probably related for the most part to plasma factors, possibly via hyperinsulinemia, even if changes in the chemical composition of the RBC membrane are not excluded, (3) RBC aggregation worsens during the first days of a hypocaloric diet; (4) rheological changes in RBC seem to be another component of the insulin resistance syndrome.