Lack of an association of urinary albumin excretion with interleukin-6 or C-reactive protein in patients with type 2 diabetes

The reason for the elevation of fibrinogen concentration in diabetic patients with nephropathy is not known so far. In order to elucidate the mechanism of such an increase in fibrinogen levels, we investigated haemorheological and inflammatory markers in type 2 diabetic patients in a cross-sectional design. Thirty-two non-smoking type 2 diabetic patients (13 women, 19 men; body mass index 29.1±5.4 kg/m², age 62.8±12.1 years) were investigated. Patietns with C-reactive protein levels > 1.5 mg/dl were excluded from the study. Concentration of fibrinogen was measured by immunonephelometry, C-reactive protein by immunoturbidimetry, and interleukin-6 (IL-6) by an enzyme-linked immunosorbent assay, and viscosity of plasma and of whole blood was determined by rotation viscosimetry. Concentrations of inflammatory parameters were well correlated with each other (p<0.05 for all correlations): IL-6 with C-reactive protein (r=0.48), and C-reactive protein with fibrinogen (r=0.41). While no associations were found with concentrations of C-reactive protein or IL-6, urinary albumin excretion was correlated with erythrocyte sedimentation rate (r=0.47) and with fibrinogen concentration (r=0.39; p<0.05). In patients with type 2 diabetes mellitus, urinary albumin excretion was not associated with concentrations of IL-6 or C-reactive protein. These results suggest an IL-6-independent mechanism for increased fibrinogen levels and erythrocyte sedimentation rate in type 2 diabetic patients with increased urinary albumin excretion. Received: February 2000 / Accepted in revised form: October 2001