Artificial Pancreas Systems AN INTRODUCTION TO THE SPECIAL ISSUE

People with diabetes cannot transfer the glucose in their bloodstream to various organs of the body for consumption or storage for later use. Blood glucose concentration (BGC) increases by absorbing carbohydrates in meals and converting them to glucose. Blood glucose is consumed by the brain for energy, stored in the liver (as glycogen) for consumption when BGC drops to low levels a few hours after a meal, and transferred to muscle and fat cells for storage and utilization. The glucose transfer to liver, muscle, and adipose tissue can happen only if enabled by insulin. Insulin is produced and secreted by the pancreas, which also produces glucagon and digestive enzymes. Diabetes is an autoimmune disease where the cells producing insulin are compromised by the immune system. If most of these cells (beta cells in the islets of Langerhans of the pancreas) are destroyed such that no insulin is produced, insulin must be administered externally to regulate BGC. Type 1 diabetes (T1D) refers to people in this state. In type 2 diabetes (T2D), some beta cells are still functional, but the total amount of insulin produced is too low or the insulin produced cannot be used effectively. The treatment options for T2D include changes in lifestyle, the use of medicine to enhance insulin productivity or utilization efficiency, and insulin administration. © 1991-2012 IEEE.