Type 1 Diabetes
Type 1 diabetes is caused by beta cell destruction, leading to insulin deficiency. T1DM was previously called insulin-dependent diabetes mellitus (IDDM), because patients who have it require insulin for survival. It was also called juvenile-onset diabetes mellitus, because most type 1 diabetics are children or young adults. At the time of diagnosis, about 85 percent to 90 percent of people with type 1 diabetes have antibodies directed against components of their beta cells, indicating that the immune system is responsible for the progressive and irreversible beta cell destruction.
Current evidence indicates a genetic component to T1DM. HLA (histocompatibility leukocyte antigen) genes are a group of genes on chromosome 6 that encode proteins that are part of the immune system. Normally the immune system defends the body against disease by destroying foreign cells, but in the case of type 1 diabetes, the body's immune system destroys its own beta cells.
Certain types of HLA genes are strongly associated with type 1 diabetes, and other types protect against its development. However, these HLA genes are neither necessary nor sufficient to cause or protect from type 1 diabetes. T1DM is therefore a "complex" genetic disorder, in which several genes interact with the environment to result in the disease. Scientists are currently working to identify these other genes, as well as environmental factors (e.g., toxins and viruses) that provoke the development of T1DM.
Medicine EncyclopediaGenetics in Medicine - Part 1Diabetes - Type 1 Diabetes, Type 2 Diabetes, Other Specific Types Of Diabetes, Genetic Susceptibility To Complications - Gestational Diabetes Mellitus