Urinary albumin excretion associated with arterial wall stiffness rather than thickness in type 2 diabetic patients

Background: A close relationship has been reported between microalbuminuria and atherosclerosis in patients with diabetes mellitus. The aim of this study was to determine which of the 2 aspects of atherosclerosis, arterial thickening or stiffness, has more effect on levels of microalbuminuria in type 2 diabetic patients. Methods: Twenty-four-hour urine samples of 167 Japanese type 2 diabetic patients (aged 58 +/- 12 years) without overt proteinuria were collected for quantitative analysis of urinary albumin excretion (UAE). Arterial stiffness was evaluated by measuring aortic pulse-wave velocity (PWV), and arterial thickness was measured by the intima-media thickness (IMT) of the carotid artery. Results: The aortic PWV and carotid IMT were both significantly positively correlated with logarithmically transformed UAE (r=0.269, p < 0.001; and r=0.188, p < 0.05, respectively). Although there was a significant positive correlation between aortic PWV and carotid IMT (r=0.263, p < 0.001), multiple regression analyses demonstrated that aortic PWV, but not carotid IMT, was a significant factor associated with log UAE, independent of other confounding factors (R-2=0.246, p < 0.0001). Conclusions: These results suggest that increased arterial stiffness, but not arterial thickness, is significantly associated with the increase in albuminuria, and that decreased arterial distensibility due to increased stiffness caused by atherosclerosis may be related to the progression of diabetic nephropathy in type 2 diabetic patients.