On lowering the risk of type 1 diabetes in genetically susceptible young people. As there is limited knowledge on the period before type 1 diabetes becomes a clinically overt disease, the aim of this explorative study was to determine whether any association exists between the medication use/disease history in the year preceding the diagnosis of type 1 diabetes and the occurrence of this disease in children and young adults. This is the first explorative population-based case control study in which disease history and drug exposures were evaluated as potential short-term triggering factors for type 1 diabetes to become clinically overt in children and young adults. We did not limit our study population to children and adolescents because type 1 diabetes can occur at any age. Our main findings demonstrate that the year prior to the presentation of overt type 1 diabetes in children and young adults, hospitalization for a substantial number of diseases and prescriptions of different drug categories were significantly more prevalent among patients with type 1 diabetes compared with diabetes-free controls. Furthermore, almost all other disease categories for which children were hospitalized such as asthma/COPD, renal/urinary disease, disease of skin and subcutaneous tissues, cardiovascular disorders, etc., although not statistically MLN4924 significant, were positively associated with type 1 diabetes. Our findings may provide some insight in the potential shortterm triggers for the manifestation of type 1 diabetes in children and young adults who are already, and sometimes for years, in a subclinical prodromal phase with diabetes-associated auto-antibodies and beta cell destruction. Such knowledge might be helpful to lower the risk of overt type 1 diabetes in children and young adults already known to be susceptible for this autoimmune disease based on e.g. a positive family history or genetic information. Prevention of certain diseases e.g. some infections or psychological stresses, and optimal treatment may prevent an increased metabolic state and thereby increased insulin requirements. Further research might reveal specific mechanisms and provide further insights into the quantitative risk by which specific diseases and drugs trigger the clinical manifestation of type 1 diabetes. Such studies might also focus on triggering risk factors that occur more than 1 year before the onset of type 1 diabetes. In addition, designing prospective observational studies for finding the environmental risk factors of type 1 diabetes e.g. TEDDY study could benefit from our findings with taking disease history and medication use into account as potential environmental risk factors of type 1 diabetes. Some of the diseases we reported as risk factors for type 1 diabetes in our study have already been published before. Examples are viral infections , gut problems , celiac disease, and severe psychological stress. Even though some mechanistic explanations have been proposed, besides that for enterovirus infections, none of those theories are classified as certain.