The remaining 10–30% of type 1 diabetics have β-cell destruction but no sign of autoimmunity; this is called idiopathic type 1 diabetes and its cause remains unclear. Environmental
Various environmental risks have been studied in an attempt to understand what triggers β-cell autoimmunity. Many aspects of environment and life history are associated with slight increases in type 1 diabetes risk, however the connection between each risk and diabetes often remains unclear. Type 1 diabetes risk is slightly higher for children whose mothers are obese or older than 35, or for children born by caesarean section. Similarly, a childs weight gain in the first year of life, total weight, and BMI are associated with slightly increased type 1 diabetes risk. Some dietary habits have also been associated with type 1 diabetes risk, namely consumption of cows milk and dietary sugar intake. Animal studies and some large human studies have found small associations between type 1 diabetes risk and intake of gluten or dietary fiber; however, other large human studies have found no such association. Many potential environmental triggers have been investigated in large human studies and found to be unassociated with type 1 diabetes risk including duration of breastfeeding, time of introduction of cow milk into the diet, vitamin D consumption, blood levels of active vitamin D, and maternal intake of omega-3 fatty acids.A longstanding hypothesis for an environmental trigger is that some viral infection early in life contributes to type 1 diabetes development.
Transplantation of the whole pancreas is rare, due in part to the few available donor organs, and to the need for lifelong immunosuppressive therapy to prevent transplant rejection. The American Diabetes Association recommends pancreas transplant only in people who also require a kidney transplant, or who struggle to perform regular insulin therapy and experience repeated severe side effects of poor blood sugar control. Most pancreas transplants are done simultaneously with a kidney transplant, with both organs from the same donor. The transplanted pancreas continues to function for at least five years in around three quarters of recipients, allowing them to stop taking insulin.Transplantations of islets alone have become increasingly common. Pancreatic islets are isolated from a donor pancreas, then injected into the recipients portal vein from which they implant onto the recipients liver. In nearly half of recipients, the islet transplant continues to work well enough that they still dont need exogenous insulin five years after transplantation. If a transplant fails, recipients can receive subsequent injections of islets from additional donors into the portal vein. Like with whole pancreas transplantation, islet transplantation requires lifelong immunosuppression and depends on the limited supply of donor organs; it is therefore similarly limited to people with severe poorly controlled diabetes and those who have had or are scheduled for a kidney transplant. Pathogenesis
Type 1 diabetes is a result of the destruction of pancreatic beta cells, although what triggers that destruction remains unclear.