Rheological effect of metformin on the blood of patients with dietetically controlled type-IIb diabetes

Metformin was added to blood samples taken from 10 patients with type-IIb diabetes, giving final contrations of 1,3, and 8 mg metformin/l. The yield shear stress of the blood, the erythrocyte rigidity and aggregration, and the plasma viscosity and fibrinogen concentration were determined under the influence of metformin in comparison with untreated control samples.

Concentrations of 1 and 3 mg metformin/l brought about a distinct and dose-dependent reduction in the aggregration tendency of the erythrocytes, and to a smaller extent in their deformability, which led to a decrease in the yield shear stress. These effects could no longer be observed at a concentration of 8 mg/l. There was no apparent effect on plasma viscosity.

This indicates the possibility that metformin, in addition to its antihyperglycaemic action, also has favourable haemorheological properties.