Impaired peripheral circulation in lower-leg arteries caused by higher arterial stiffness and greater vascular resistance associates with nephropathy in type 2 diabetic patients with normal ankle–brachial indices

Diabetic nephropathy is a major cause of lower-limb amputation. We enrolled 250 type 2 diabetic patients without apparent occlusive peripheral arterial disease (ankle–brachial indices >0.9) and 40 age-matched nondiabetic subjects consecutively admitted to our hospital. Flow volume and resistive index (RI), an index of vascular resistance, at the popliteal artery were evaluated using gated two-dimensional cine-mode phase-contrast magnetic resonance imaging. Brachial–ankle pulse wave velocity (baPWV) was measured as an index of arterial distensibility. Flow volume was negatively correlated with both baPWV (p = 0.0009) and RI (p < 0.0001) among the patients. When the patients were grouped into four subgroups with or without albuminuria and renal insufficiency according to the levels of urinary albumin excretion rate (≥20 or <20 μg/min) and estimated glomerular filtration rate (eGFR) (<60 or ≥60 ml/min/1.73 m2), albuminuric patients with renal insufficiency (n = 30) showed the lowest flow volume (p = 0.0078) and the highest baPWV (p = 0.0006) and RI (p = 0.0274) among the groups. Simple linear regression analyses demonstrated that eGFR correlated positively with flow volume (p = 0.0020) and negatively with baPWV (p = 0.0258) and RI (p = 0.0029) in patients with albuminuria (n = 92), but not with normoalbuminuria (n = 158). Impaired peripheral circulation in lower-leg arteries associates with nephropathy in diabetic patients even though they have normal ankle–brachial indices.