Coeliac disease (CD) and autoimmune thyreoiditis (AIT) are associated with type-1 diabetes. These diseases frequently occur without apparent clinical symptoms. Therefore, a serological screening by autoantibody testing is required for early detection. Identified by screening, the prevalence of CD and AIT is reported to be up to 10-fold higher in young patients with type-1 diabetes than in healthy children. Up to now, no uniform recommendations exist regarding a standardized screening procedure as well as the treatment of patients with clinically asymptomatic disorder and evidence of autoimmunity. A delay in the detection of associated diseases, however, may lead to clinical relevant, but otherwise preventable complications.