The effect of improvement in diabetic control on plasma and whole blood viscosity.

Rheological studies were made on the blood of 12 diabetic patients after a period of poor diabetic control (HbA1 12.6 +/- 0.7% (mean +/- SD); mean home capillary blood glucose level 11.7 +/- 1.2 mmol/l), and after at least three months of improved control (HbA1 9.1 +/- 0.4%, p < 0.01; mean home capillary blood glucose level 9.2 +/- 0.6 mmol/l). There were significant decreases in plasma fibrinogen levels (4.1 +/- 0.6 to 3.7 +/- 0.6 g/l, p < 0.01), plasma viscosity (1.31 +/- 0.1 to 1.25 +/- 0.04, p < 0.001), and whole blood viscosity at low (22.8 +/- 2.7 to 20.2 +/- 2.9, p < 0.01) and high shear rates (3.4 +/- 0.2 to 3.1 +/- 0.2, p < 0.01). Ten diabetics with clinically evident complications were matched with diabetics of similar age, sex, duration and current control of diabetes. There were no significant differences in plasma or whole blood viscosities between the two groups. Hyperviscosity in diabetes seems strongly related to hyperglycaemia and to be influenced by the quality of diabetic control.