**3. The immunological disease process**

The generally accepted opinion is that the majority of the pancreatic beta cells are lost at the diagnosis of Type 1 diabetes. The beta cells are supposed to be killed by an autoimmune process precipitated and promoted by genetic and environmental factors. In recent years the dogma saying that most beta cells are dead has been questioned, and regeneration of the beta cells seems not only possible but quite plausible. Actually that was discussed as a possibility already several decades ago( Fig 1). Thus, many beta cells may still be living in pancreas although they do not respond normally to stimulus with insulin secretion. Auto-antibodies are usually found, but regarded as markers of the process, rather than causing beta cell death. The auto-antibodies react against the islet cells (Islet Cell Antibodies; ICA) [16] or against specific auto-antigens such as Insulin Auto-antibodies against Insulin (IAA) [17], against Glutamic Acid Decarbox‐ ylase (GADA) [18], against Tyrosin Phosphatase ( IA-2A) [19] or against ZincTransport Anti‐ gen (ZnTA) [20]. These antigens are attacked by the own immune system. Dysregulation of the immune system is thought to allow a self-destructive process. Mononuclear cells, mainly T-cells, seem to play the most important role for the killing of the beta cells.
