Comparison of Duplex Ultrasound Blood Flow Characteristics of the Lower Limb in Diabetics with Early-Stage Peripheral Artery Disease and Non-Diabetic Controls among the Black African Population

The aim of this study was to compare lower limb blood flow in asymptomatic diabetic patients with early-stage peripheral artery disease (PAD) and non-diabetic controls using duplex ultrasound parameters. Duplex ultrasound (DUS) has documented high sensitivity and specificity in detecting late-stage peripheral artery Disease (PAD), both in the upper and lower extremity arteries, while being capable of demonstrating plaque which causes less than 50% stenosis in diabetic subjects. This was a comparative cohort study of lower limb blood flow in 35 Black African diabetic patients (25 females and 10 males with early-stage PAD median age 54 [IQR, 47 - 6I] years; median HbA1c 6.3[IQR, 5.7–8.0] %; BMI 29.2±6.7; ABI 1.1±0.1) and 36 non-diabetic controls (28 females and 8 males; median age 54[IQR,47-61] years; median HbA1c 6.3[IQR, 5.7-8.0] %, BMI 29.2 ±6.7;ABI1.1±0.1). Peak systolic velocity (PSV), pulsatility index (PI) and resistive index (RI) were utilised to compare blood flow in the popliteal arteries (PA), anterior tibial arteries (ATA) and posterior tibial arteries (PTA) in addition to ankle-brachial index. All the ultrasound parameters showed good (ICC 0.7;0.50-0.85,95%Cl) to excellent (ICC=1.0; 1.0 - 1.0, 95% CI) reliability within groups as well as acceptable variability (<10% CV) other than pulsatility index of the anterior tibial artery within diabetic patients (11.1%CV). PSV, RI and PI were significantly and meaningfully higher (P<0.001;d
0.33), in diabetic patients compared to nondiabetic controls except for PI - PTA (P=0.72;d=0.11). Late-stage PAD results in pressure reduction in the ankle arteries while the upper arm arteries will still be yet unaffected, thus resulting in a lower value for Ankle Brachial Index in such patients. Differences in PSV and RI highlighted the effects of early-stage PAD on the lower limb blood flow of diabetic patients. In contrast, the effects of early-stage PAD on blood flow were not demonstrated in the PTA and ATA of diabetic patients by PI.