Blood rheology was investigated in patients with diabetic nephropathy and progressive renal insufficiency, and compared with similar non‐diabetic patients and healthy control subjects. Plasma viscosity and whole blood viscosity at standardized haematocrit were elevated to a comparable degree in the two patient groups, but erythrocyte deformability was normal. In diabetic patients, the rate of progression of renal failure showed weak, but significant, correlations with plasma viscosity (rs = 0.50, p = 0.005), standardized whole blood viscosity (rs = 0.41, p = 0.021), plasma fibrinogen (rs = 0.46, p = 0.010), C reactive protein (rs = 0.40, p = 0.023), and proteinuria (rs = 0.52, p = 0.003). Both plasma viscosity and plasma fibrinogen correlated significantly with proteinuria (rs = 0.45, p = 0.012 and 0.40, p = 0.027, respectively). Rheological abnormality is probably a manifestation of increased acute phase proteins, but it remains to be determined whether these are the cause or the effect of the renal injury. Abnormal blood rheology may be a risk factor for the progression of renal failure in diabetic nephropathy. 1990 Diabetes UK
