Although type 1 diabetes may occur in anyone, there is a greater risk of developing the disease with the following factors:

• Family history of diabetes (parent, sister, brother)
• Age less than 30
• White race, particularly Northern European ancestry
• Certain genes
• Children fed breast-milk substitutes

Family history plays a clear role in the risk for developing type 1 diabetes. The risk changes depending on which family member has the diabetes. According to the ADA, a person’s risk is affected as follows for each family member diagnosed with diabetes:

Family history is not the only hereditary factor that can contribute to type 1 diabetes. Individuals may inherit certain DNA and antibodies that place them at risk for developing type 1 diabetes. The genes (HLA-DR3 and HLA-DR4) are useful in predicting the risk for type 1 diabetes, particularly in children. Special tests may be conducted to examine the DNA and determine the existence of antibodies. If the parents are white, have diabetes and have these genes, the children are at the highest risk for developing type 1 diabetes. However, not all people who have these genes will develop type 1 diabetes.

Researchers believe that environmental factors, not just genetics, contribute to the development of type 1 diabetes. In studies conducted by the ADA on identical twins, it was discovered that genetics alone could not be responsible for type 1 diabetes. Identical twins have identical genes, yet when one twin has type 1 diabetes, the other has at most a 50 percent chance of developing the disease. Although some environmental factors may contribute to the development of type 1 diabetes, it is unclear which factors increase the risk.

It is suspected that viruses and possibly early nutrition may be risk factors. However, there is no clear evidence that suggests changing controlled factors can lower the risk for developing type 1 diabetes.