The present invention relates to a method for diagnosing diabetes or a predisposition thereof comprising determining at least one metabolite in a test sample of a subject suspected to suffer from diabetes or to have a predisposition therefor and comparing said at least one metabolite to a reference, whereby diabetes or a predisposition therefor is to be diagnosed. Moreover, the present invention encompasses a collection of metabolites, a data collection comprising characteristic values of metabolites and a storage medium comprising said data collection. Furthermore, the present invention also relates to a system comprising means for comparing characteristic values of metabolites of a sample operatively linked to a data storage medium. Further encompassed by the present invention are diagnostic means comprising at least one metabolite and the use of said at least one metabolite for the manufacture of diagnostic means for diagnosing diabetes. Finally, the present invention pertains to a method for identifying diabetes-related metabolites.