April 2, 2018Metabolism
Diabetes mellitus type 1 (also known as type 1 diabetes) is a form of diabetes mellitus in which not enough insulin is produced, resulting in high blood sugar levels in the body. Pancreatic islets release the hormone insulin, which helps control blood glucose levels. In type 1 diabetes, the body's immune system attacks and destroys the insulin-producing cells in islets. People with the disease must take insulin to live, but insulin injections or pumps cannot control blood glucose levels as precisely as insulin released naturally from the pancreas. Even with diligent monitoring, blood glucose can often reach levels that are higher or lower than normal. A low blood glucose level, or hypoglycemia, typically is accompanied by tremors, sweating, nausea and/or heart palpitations. These symptoms prompt the person to eat or drink to raise their blood glucose. However, some people do not experience these early warning signs. This impaired awareness of hypoglycemia raises the risk of potentially life-threatening severe hypoglycemic events, during which the person is unable to treat himself or herself. These episodes can lead to accidents, injuries, coma and death.
According to an article published online in Diabetes Care (21 March 2018), quality of life for people with type 1 diabetes who had frequent severe hypoglycemia -- a potentially fatal low blood glucose (blood sugar) level -- improved consistently and dramatically following transplantation of insulin-producing pancreatic islets. The results come from a Phase 3 clinical trial funded by the National Institute of Allergy and Infectious Diseases (NIAID) and the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), both part of the National Institutes of Health. The trial enrolled 48 people with type 1 diabetes who had hypoglycemia unawareness -- an impaired ability to sense drops in blood glucose levels -- and experienced frequent episodes of severe hypoglycemia despite receiving expert care. Results showed the greatest improvements in diabetes-related quality of life. Islet recipients also reported better overall health status after transplant, despite the need for lifelong treatment with immune-suppressing drugs to prevent transplant rejection. The authors observed these improvements even among transplant recipients who still required insulin therapy to manage their diabetes.
Previously reported clinical outcomes from the trial showed that islet transplantation prevents severe hypoglycemia and improves blood glucose awareness and control. The study was conducted by the NIH-funded Clinical Islet Transplantation Consortium.
For the study, all 48 study participants received at least one islet transplant. One year after their first transplant, 42 participants (88 percent) were free of severe hypoglycemic events, had established near-normal blood glucose control, and had restored awareness of hypoglycemia. Only a small number of functional insulin-producing cells are necessary to restore hypoglycemic awareness, but this amount may not be sufficient to fully regulate a person's blood glucose levels. Approximately half of the transplant recipients needed to continue taking insulin to control their blood glucose levels. The study design incorporated four well-established, commercially available quality-of-life surveys that were given to participants repeatedly before and after islet transplantation. Two of the surveys were specific for diabetes, while two assessed health more generally. Reported improvements in quality of life were similar among islet recipients who still needed to take insulin to manage their diabetes and those who did not. The authors concluded that elimination of severe hypoglycemia and the associated fears accounted for these improvements, appearing to outweigh concerns about the need to continue insulin injections.
Islet transplantation is an investigational therapy in the United States. While promising for people whose type 1 diabetes cannot be controlled with standard treatments, the procedure is not appropriate for most people with type 1 diabetes, as there are risks associated with the transplant procedure, such as bleeding, as well as side effects of immunosuppressive medications, such as decreased kidney function and increased susceptibility to infections.