Diabetes is a chronic metabolic disease that poses a serious threat to human health and is the third most common human disease after cardiovascular disease and cancer. According to the 2006 report of the International Diabetes Federation (IDF), there are about 230 million diabetic patients worldwide, and the annual cost of diabetes treatment in developed countries accounts for 9-15% of their overall national health care costs. China currently has about 30 million diabetic patients, and the annual health care costs for diabetes are up to 250 billion, and increasing year by year. It is expected that by 2030, China will have more than 40 million people with diabetes, jumping to the first place in the world. Diabetes has become a major social and economic problem that threatens the health and lives of all human beings. The biggest threat to diabetic patients comes from their microvascular complications, which in turn affect the heart, brain, kidneys and other organs. The incidence of vascular complications increases 3 to 5 times after 20 years of disease compared to non-diabetic patients. The increase in mortality from cardiovascular disease in combination with diabetes is very significant, with a 2-fold increase in mortality in men and nearly a 5-fold increase in women compared to patients without a history of diabetes. Renal failure due to diabetic nephropathy has risen to the top three clinical renal transplants. Blindness due to diabetic eye disease has approached or surpassed the number of blindness due to glaucoma. Various long-term complications are the leading cause of death in patients with diabetes. In order to reduce the incidence of diabetic complications and mortality, comprehensive measures such as reducing patients’ hypertension and hyperlipidemia and using insulin pumps to precisely adjust blood glucose are often used clinically. Although conventional exogenous insulin replacement can improve patients’ glucose metabolism disorders to a certain extent, its pulsatile injection cannot effectively regulate the fluctuation of body glucose, and long-term or intermittent hyperglycemia and various metabolic disorders such as lipids and proteins will still eventually lead to microvascular and nerve damage. In addition, it is also believed that the exogenous insulin used for injection in clinical practice can accelerate vascular sclerosis. Under normal physiological conditions, insulin secreted by the pancreas first enters the liver through the portal vein system, and liver cells are the main target organ of insulin. The insulin injection therapy, however, enters the body circulation first via subcutaneous or venous route, and forms hyperinsulinemia in the periphery. In addition to lowering blood glucose, another important physiological role of insulin is to promote fat synthesis, and the consequence of peripheral hyperinsulinemia is peripheral vascular atherosclerosis. Therefore, patients who receive insulin injections for a long period of time are not immune to serious complications such as renal failure and blindness. In order to solve the problem of fine regulation and endogenous secretion of insulin, two methods can be used in theory. One of them is the insulin pump in vivo implantation technique. Insulin pump is an insulin input method developed from insulin injection pen technology. The in vitro insulin pump uses open-loop regulation, and the technology is relatively simple and stable, which has been accepted by many patients. Insulin pump in vivo implantation technology uses closed-loop regulation, the key point of which is the sensitivity and aging of blood glucose receptors. Due to the failure of the receptors, clinical trials have been halted due to the death of the patients tested. The second approach is to perform pancreas or islet transplantation. Pancreatic transplantation has been used clinically since the 1960s, and the success rate has been increasing year by year, with a 1-year survival rate of about 90%. However, pancreatic transplantation is very invasive, with many surgical complications, and the long-term survival rate still needs to be improved. Adult islet transplantation began clinical trials in the 1970s and was successful in the 1990s. Its advantages are less trauma, lower mortality rate and no tissue matching required. Especially after 2000, the success rate of islet transplantation in many foreign centers has reached 60C100 %. Islet transplantation is now widely performed in Europe and the United States. Compared with traditional insulin replacement therapy, islet cell transplantation has the advantages of stable and precise regulation of blood glucose, physiological characteristics, and no risk of hypoglycemia. It can effectively correct fat metabolism disorders, reduce the development of complications during the natural course of diabetes or during insulin therapy, and even reverse some early complications. Therefore, the study of islet transplantation for diabetes has great academic value, social effects and application prospects.