They appear to involve abnormal interactions among normal genes, mostly those known as class I and II major histocompatibility genes, which affect the immune response. Children are more likely to inherit the disease from a father with type 1 diabetes than from a mother with the disorder. Genetic factors, however, cannot fully explain the development of diabetes. If genetic factors were the only cause of type 1 diabetes, such an increase in cases would take at least 400 years. Some researchers believe one or more viral infections may trigger the disease in genetically susceptible individuals.
Researchers suggest that an infection introduces a viral protein resembling a beta-cell protein.
The T cells and antibodies to the foreign protein are tricked by this resemblance into attacking the beta protein as well as the virus. Cow's Milk Under investigation is a link between type 1 diabetes and exposure to cow's milk early in infancy. Some researchers believe that the antibodies formed to respond to BSA may later on attack the child's beta-cells. Up to 800,000 people in the U.S. are estimated to have type 1 diabetes, with about 30,000 new cases diagnosed each year. Type 1 can occur at any age but usually appears between infancy and the late 30s, most typically in childhood or adolescence.