Association of hypertension with blood viscosity in diabetes.

Plasma and whole blood viscosity and its determinants were measured in 86 diabetic patients (29 hypertensive and 57 normotensive) and compared with 52 non-diabetic control subjects to assess whether hypertension has an additive and adverse effect on blood viscosity. Whole blood viscosity (corrected for haematocrit), at high and low shear rates (95 and 0.95 s-1), was significantly higher in both Type 1 (5.1 +/- 0.5 (+/- SD), 19.8 +/- 2.9) and Type 2 (5.2 +/- 0.3, 21.1 +/- 2.0) diabetic patients compared with control subjects (4.9 +/- 0.6, 17.4 +/- 2.6 mPa s, p less than 0.01). Corrected whole blood viscosity at high shear rate was significantly higher in hypertensive than in normotensive Type 2 diabetic patients (5.5 +/- 0.4 vs 5.2 +/- 0.3 mPa s, p less than 0.01). Plasma viscosity was significantly higher in diabetic patients compared with control subjects (1.4 +/- 0.1 vs 1.3 +/- 0.1 mPa s, p less than 0.01), but there was no difference between hypertensive and normotensive diabetic patients (1.4 +/- 0.1 vs 1.4 +/- 0.2 mPa s). Fibrinogen levels were similar in all the groups.