Long-term poor glycemic control can cause chronic damage to peripheral tissues and organs, and chronic complications of diabetes are mainly focused on macroangiopathy, diabetic microangiopathy, and peripheral neuropathy. Diabetic macrovascular disease can be divided into cerebrovascular disease, cardiovascular disease, and atherosclerosis of limb arteries or arterial occlusion of lower limb vessels. Cerebrovascular lesions can appear as cerebral infarction and cerebral hemorrhage; cardiovascular lesions are coronary atherosclerotic heart disease represented by angina pectoris, myocardial infarction, and heart failure; microvascular lesions are mainly manifested as diabetic retinopathy and diabetic nephropathy, with clinical manifestations such as decreased vision, blurred vision, swelling of lower limbs, increased nocturia, and increased white foam in urine. Diabetic peripheral neuropathy mainly manifests as abnormal numbness, tingling and coldness in the extremities, etc. Long-term hyperglycemia may accelerate the occurrence of glaucoma and cataract.