Among the systemic macrovascular lesions caused by diabetes, the most vulnerable are the coronary arteries, cerebral arteries and lower extremity arteries. The result of these arterial lesions eventually leads to angina pectoris, myocardial infarction, cerebral insufficiency, cerebral thrombosis, cerebral hemorrhage, cold chills in the lower extremities, intermittent claudication and gangrene of the lower extremities. In the previous lectures, I talked about cardiovascular complications as the main cause of death in diabetes, and today I will focus on the clinical features and diagnostic treatment of lower extremity vascular lesions. Although these vascular lesions also occur in the non-diabetic population, the incidence of cardiovascular disease is several times higher in the diabetic population, but the incidence of lower extremity gangrene leading to amputation is 15 to 20 times higher. In the early stages of vascular disease in the lower extremities of diabetic patients, there is usually only partial blockage of blood vessels, and blood flow becomes slow through difficulties, resulting in ischemia and hypoxia in muscles and other tissues, and metabolic disorders. In the early stage, patients often feel cold and afraid of cold in the lower limbs. As the disease progresses, pain in the lower limbs may appear after walking for a period of time, and the symptoms may be relieved after resting or massaging for a while, which is called intermittent claudication. When the degree of vascular obstruction increases, the ischemia and hypoxia will worsen, and the pain in the limbs will be worse even at rest, mostly during sleep at night, and can be relieved by dropping the lower limbs. Ischemic gangrene occurs when blood flow is completely blocked by a blood clot. When ischemic disorders of the lower extremities occur, the patient will have abnormal sensation, numbness in both or one limb, a feeling of coldness, and pain in the calf or foot when walking. Abnormalities in the color of the lower extremities can be detected with the naked eye, such as gray skin or localized cyanosis or pallor, venous stasis, thinning of the limb due to muscle atrophy, edema, ischemic ulcers, and further tissue necrosis. There are also abnormal changes of nails and body hair. The skin temperature of the affected limb can be felt to decrease by touch. In addition to the above symptoms and signs, some simple tests can be used to confirm occlusive lesions of the limb vessels. For example, the temperature of the limb surface can be measured, the pulsation of the dorsalis pedis and posterior tibial artery can be touched to see if it is weakened or disappeared, and the color of the skin can be observed after the limb is lifted or lowered. The diagnosis can also be further confirmed by special tests such as angiography and color Doppler ultrasonography. Especially the latter, with which the whole lower limb blood vessels can be scanned to find out what parts are narrowed, blocked and the degree of narrowing and blockage. Even if you have lower extremity vascular sclerosis occlusive disease, you do not have to be overly nervous or even lose confidence in the cure, as long as you pay high attention and actively cooperate with your doctor, the condition can still be controlled. In order to slow down and stop this disabling vascular damage, we must first strictly control blood sugar, correct lipid metabolism disorders, lower hypertension, reduce inflammatory reactions, change blood rheology and hypercoagulability, and also dilate blood vessels to increase blood flow. When diabetic patients show early symptoms of vascular damage in the lower limbs, such as fear of cold, intermittent claudication, pain at night and numbness and coldness in the legs, they should pay high attention to and actively prevent the progress of atherosclerosis and thrombus formation. There are many new clinical drugs that can be applied to open up new ways for the treatment of diabetic peripheral vascular complications. A large number of clinical practice has proved that the use of the above-mentioned comprehensive treatment can significantly improve the lower limb ischemic symptoms such as pain, numbness and coldness due to vaso-occlusive lesions, and in some cases can be completely cured.