There are three major nutrients in the human body – sugar, fat and protein, and their metabolism in the human body is interrelated, of which an increase in blood sugar will affect the metabolism of the other two substances. The effect on blood lipids is especially important, which can cause disorders of lipid metabolism (mostly manifested as hyperlipidemia), thus easily causing arterial lumen narrowing and occlusion. The blood vessels of the lower extremities are the longest blood supply channels in the body, and any narrowing or occlusion at any stage will affect the blood supply to the distal tissues up to the foot, a lesion medically called diabetic macroangiopathy. In addition, hyperglycemia can cause degeneration and thickening of the microvascular wall, narrowing and occlusion of the lumen, leading to ischemia and hypoxia in the lower extremity. At the same time, the physical and chemical properties of the blood of diabetic patients also change (including a decrease in the oxygen-carrying capacity of red blood cells, the tendency of platelets to adhere and gather to form thrombi, and an increase in blood viscosity), and the combination of these factors results in severe ischemia and hypoxia in the foot, which eventually leads to tissue necrosis – diabetic microvascular gangrene. In addition, neurotrophic disorders and ischemic neuritis caused by macrovascular and microvascular lesions make the body lack protective measures for the foot (because of the weakening or loss of protective sensation at the end of the limb), which can easily lead to physical damage, and once damaged, pathophysiological changes make it difficult to repair and control the infection, which eventually develops into foot gangrene. Finally, infection is an important factor that contributes to the aggravation of diabetic foot. We all know that people with diabetes are prone to infections, most commonly skin infections, because of the low immunity of diabetic patients. The lower extremities are the most weight-bearing organs in the body, especially the feet, which are most prone to injury and are more prone to infection in ischemic limbs. Due to the presence of neuropathy and peripheral vascular lesions, small trauma can cause microbial invasion and infection, and the high glucose status of diabetic patients provides rich nutrients for bacterial growth and reproduction, thus making the infection more likely to spread.