Associations of Renal Vascular Resistance With Albuminuria and Other Macroangiopathy in Type 2 Diabetic Patients

OBJECTIVE Albuminuria can be caused by endothelial dysfunction as a result of ischemic nephropathy rather than classic diabetic nephropathy. We studied whether renal vascular resistance (resistive index [RI]) of the main renal arteries could be associated with albuminuria and further assessed the relationship between RI and aorta stiffness measured by brachial-ankle pulse-wave velocity (baPWV). RESEARCH DESIGN AND METHODS We consecutively studied 150 patients with type 2 diabetes and the absence of clinically overt renal artery stenosis. Renal function expressed as the estimated glomerular filtration rate (eGFR) was calculated using the modified formula of modification of diet in renal disease (MDRD). The RI [(peak systolic velocity -end-diastolic velocity)/peak systolic velocity] was measured with duplex Doppler ultrasonography. RESULTS When the presence of albuminuria (uAlb) was defined as urinary albumin-to-creatinine ratio (microg/mg x creatinine) >30, mean RI [(left RI + right RI)/2] was significantly higher in uAlb, compared with that in patients without uAlb. RI had significant associations with age (r = 0.398, P < 0.0001), diastolic blood pressure (r = -0.398, P < 0.0001), eGFR (r = -0.373, P < 0.0001), and baPWV (r = 0.223, P < 0.05), respectively. Multivariate logistic regression analysis showed that increased RI when defined as RI >0.72 (median) was significantly associated with age (P < 0.01, 95%CI 1.02-1.19), diastolic blood pressure (P < 0.01, 0.86-0.97), and uAlb (P < 0.01, 1.53-15.46), respectively. Moreover, RI was an independent risk factor for uAlb after adjustment of both diastolic blood pressure and eGFR. CONCLUSIONS Renal vascular resistance was associated with albuminuria and aorta stiffness. Increased RI may imply the presence of any type of underlying renal damage, including ischemic nephropathy.