Diabetes Mellitus and Lower Extremity Peripheral Artery Disease

Lower extremity peripheral artery disease, or often simply called peripheral artery disease (PAD), is a common cardiovascular disease, as coronary artery disease is. Atherosclerotic disease of the arteries of the lower extremity, or arteriosclerosis obliterans, accounts for the vast majority of PAD today. Rest pain, nonhealing ulcers, and gangrenes associated with chronic ischemia (i.e., Fontaine stage III and IV or Rutherford category 4 to 6) are referred to as chronic limb-threatening ischemia (CLTI), formally called critical limb ischemia (CLI). This narrative review focuses on atherosclerotic PAD, especially CLTI, mainly highlighting its link with diabetes mellitus (DM). This article will first overview the clinical impact of DM in patients with symptomatic PAD and that of symptomatic PAD in patients with DM, followed by the clinical features of CLTI, which will be discussed from a viewpoint of its prognosis, patient profile, onset, and seasonality. DM poses a great clinical impact on CLTI, and vice versa. Patient profile appears different between DM patients complicated with CLTI and the general population with DM. Furthermore, although CLTI is pathologically rooted in atherosclerosis as is acute coronary syndrome (ACS), CLTI has considerably different clinical features compared with ACS. CLTI has an extremely poor prognosis even after revascularization, and there is ample room for improvement in terms of its prognosis. Some measures might be needed in healthcare and clinical settings before revascularization: e.g., DM control and regular ischemia risk evaluation before CLTI onset, proper diagnosis at CLTI onset, and prompt referral to a vascular specialist after CLTI onset, although its evidence is still scanty. Piling up evidence of patients with CLTI, by patients with CLTI, and for patients with CLTI is needed.