Since the world’s first insulin was injected into a human a century ago, efforts focused mainly on improving insulin treatment for diagnosed patients. Today, preventive therapy is being researched as the next milestone, and an increasing number of countries are discussing strategies to identify the target population for such treatments. To this end, existing data sets from observational cohort studies can be used together with known risk predictors such as islet autoantibodies, human leukocyte antigen (HLA) haplotypes and genetic risk scores. The challenge now is to translate this knowledge into effective screening strategies.