Untreated diabetes and poor long-term blood glucose control can lead to multiple organ complications. If the complications involve the cardiovascular system, atherosclerosis, coronary artery disease, and in severe cases, angina pectoris, myocardial infarction and cerebral infarction can occur. If the complications involve the autonomic and peripheral nervous systems, cardiac autonomic neuropathy can occur, and numbness and burning sensations in the terminal limbs can occur. If the eye is involved, there will be lesions of the blood vessels in the fundus, macular lesions, blurred vision and loss of vision. If bleeding or blockage of the fundus occurs, it can also cause blindness. If the kidneys are involved, there may be an increase in urine protein in the early stage, and as the disease progresses, the kidney function may deteriorate, and in severe cases, uremia may occur. If the lesion involves the blood vessels and nerves of the lower limbs, it will cause abnormal blood supply to the blood vessels and nervous system and loss of peripheral sensation, which will lead to the formation of diabetic foot ulcers, which is often called diabetic foot, with the risk of amputation or even life-threatening. Therefore, once diabetes is diagnosed, it is important to actively treat it and prevent complications.