There are many reports on the relationship between diabetes and micronutrients. Studies have shown that diabetes mellitus is closely related to lipid peroxidation. It is well known that a certain dose of selenium has the effect of scavenging free radicals, and selenium-containing enzymes play a pivotal role in the antioxidant system of the body. Therefore, the relationship between selenium and diabetes has received much attention in recent years, and a brief review of the research progress on selenium and diabetes is presented. The endocrine cells of pancreatic islets are 60-80% β-cells. When the damage to pancreatic islets reaches a certain level, the function of β-cells to secrete insulin will be reduced, causing the lack of insulin in human body, and the disorder of glucose metabolism will appear, showing the increase of blood glucose level and large amount of urine sugar discharge, called diabetes mellitus. Can diabetes be prevented and treated? Take a look at the results of the study on the mechanism of islet damage: It was found that when the islet secretion function was damaged, the GPx activity of serum and pancreatic tissue was significantly reduced and the lipid peroxide content was significantly increased, and after selenium supplementation, the islet secretion function was improved along with the increase of serum and pancreatic GPX activity level and the significant reduction of lipid peroxide content. This indicates that the injury to pancreatic islets is a peroxidative damage caused by selenium deficiency. It was observed that GPx (glutathione peroxidase), SOD (catalase) were decreased or decreasing in diabetic mice, and selenium supplementation significantly increased GPx and SOD activities. On the other hand, the lipid peroxide content in the pancreas of diabetic mice was significantly increased, and selenium supplementation could also significantly decrease it. After oral administration of selenium to diabetic patients, a significant increase in islet GPx activity and a significant decrease in plasma lipid peroxide levels were observed, indicating the significance of selenium in the treatment and prevention of diabetes and its complications. Selenium deficiency decreases the GPx activity of islets, exposing the endoplasmic reticulum to free radical attack, and the injured endoplasmic reticulum reduces insulin secretion. Selenium supplementation can maintain the proper activity of GPx, which can prevent the endoplasmic reticulum from being attacked by free radicals and injured, and a sound endoplasmic reticulum can secrete insulin normally. Selenium to prevent and treat complications of diabetes: How to prevent and treat complications of diabetes is another hot topic of research. Hyperglycemic state is the main cause of chronic complications of diabetes. Elevated blood glucose concentration makes the blood sticky, which can cause vascular lesions over time. The major macrovascular lesions complicated by diabetes are coronary heart disease, myocardial infarction, cerebral infarction and cerebral hemorrhage are the main causes of death in diabetic patients. Insufficient insulin secretion is certainly a serious threat to the myocardium. Selenium can significantly improve the uptake and utilization of insulin by cardiomyocytes, improve the nutrient metabolism of cardiomyocytes in diabetic patients, protect the normal function of cardiomyocytes, and play a very important role in preventing the occurrence and development of cardiomyopathy. Diabetic complications of microangiopathy mainly include retinopathy, nephropathy and neuropathy. Clinical manifestations may include symmetrical numbness and pain in the extremities, blurred vision, swelling of the lower extremities, proteinuria, and in severe cases, blindness and renal failure. The eye damage caused by diabetes is also prominent. Patients almost always have varying degrees of vision loss, and the longer the number of years of disease, the more pronounced the symptoms. According to the data, 47% of the cases are complicated by cataracts and 35.6% by retinopathy, which can cause blindness in severe cases. Among the various types of cataracts, diabetic cataract is the most studied and the most in-depth one. In cases such as the above, selenium supplementation should be appropriate. Oxidative damage of the lens is an important mechanism for cataract formation, and selenium is the active substance of antioxidant enzymes in the lens, which can reduce oxidative damage of the lens and retina. Therefore, it has been reported that “trace elements of selenium have a real benefit in the prevention and treatment of visual impairment in diabetes”. Selenium promotes cellular absorption and utilization of sugar in fat, muscle and other peripheral tissues, inhibits hepatic glycogenesis and decomposition in the liver, and increases hepatic glycogen synthesis. At the same time, selenium protects the normal function of insulin and protects liver function, thus maintaining the important role of the liver in glucose metabolism. The pathological response of these complications in vivo is extensive glycosylation and oxidative damage, which causes a variety of organ complications due to tissue hypoxia, and selenium has a significant inhibitory effect on them, which is beneficial for diabetic patients to control their complications. In a word, selenium supplementation can regulate immune function and antioxidant function. Diabetes and the trace element selenium are closely linked. However, the relationship between the level of selenium in the body and glucose metabolism, especially the exact mechanism about the insulin-like effect of selenium still needs further study, which is of some significance for the micronutrient-assisted treatment of diabetes.