I've listened to Gary Gibbons, MD (vascular surgeon, the Deaconess, Boston) on multiple occasions state that diabetic patients with a threatened limb require maximal flow to heal. I believe we have all seen patients like Dr. Liu describes. In a patient that presents with a new wound to my center, we always obtain non-invasive measures macrovascular flow (ABI, TBI, segmental pressures, PVR). I am surprised how often they don't correlate with the presence or absence of pulses. We often obtain microvascular measures as well (OxyVu, but TcPO2, SPP are adequate too). It is also surprising seeing the discordance between macro and micro vascular studies.
Also, remember about 8% of healthy patients have a non palpable DP pulse, and anatomical studies have shown the DP artery to be absent 2% of the time.