Norway is among the countries with the highest prevalence of type 1-diabetes, and the incidence is increasing. Both environmental- and genetic factors contribute to development of the disease; but no environmental risk factor for type 1-diabetes has been identified, and it is therefore difficult to prevent the disease. In the prospective research study MIDIA (Norwegian acronym for Environmental triggers of type 1-diabetes) 100,000 new-borns will be tested for a gene combination that approximately 2.1% of the children have. Each of the 2,100 children with this combination have a 6-10% risk for childhood diabetes. They will be followed for up for 15 years with regular stool samples, questionnaires and blood samples with the aim of finding causes of diabetes. Detection of autoantibodies towards beta cells in the pancreas indicates an ongoing disease process and will be used as the first end-point. The aim of this article is to inform Norwegian doctors about the study, and to discuss scientific and ethical aspects of the project.