Prevalence and major risk factors of reduced flow volume in lower extremities with normal ankle-brachial index in Japanese patients with type 2 diabetes

Abstract

OBJECTIVE - To clarify the prevalence and major risk factors of reduced flow volume in lower extremities with normal ankle-brachial index (ABI) in Japanese patients with type 2 diabetes. RESEARCH DESIGN AND METHODS - We recruited 208 consecutive type 2 diabetic patients and 33 age-matched nondiabetic subjects (control group) admitted to our hospital. Thirty-two of the patients had low ABI (<0.90) and intermittent claudication (peripheral arterial disease [PAD] group), and 176 patients had normal ABI (>0.9) (non-PAD group). We evaluated flow volume and resistive index, as an index of arterial resistance to blood flow, at the popliteal artery using gated two-dimensional cine-mode phase-contrast magnetic resonance imaging. RESULTS - Simple linear regression analysis showed a negative correlation between resistive index and total flow volume in the non-PAD group (r = -0.714, P < 0.001). We defined the means ± 2 SD of these parameters in the control group as the normal range; abnormal resistive index was >1.017, and abnormal flow volume was <50.8 ml/min. The non-PAD group was divided according to the levels of these parameters: 80 patients had both normal resistive index and normal flow volume (normal group); of 96 patients with higher resistive index, 63 had normal flow volume (borderline group) and 33 had reduced flow volume (reduced group). Multiple regression analysis demonstrated that the major risk factors for reduced flow volume were age, hypertension, and diabetic nephropathy (r2 = 0.303, P < 0.001). CONCLUSIONS - The prevalence of patients without PAD with reduced flow volume in the lower extremities was 16% (n = 33) and comparable with that of patients with PAD with intermittent claudication (n = 32), suggesting that increase in arterial resistance to blood flow may be one of the major causes of lower extremity arterial disease in Japan.