OBJECTIVES: Despite the rapid development of pharmacoeconomics and outcomes research in new countries joining European Union (EU) there is still scarcity of cost of illness studies compared to old EU members. The aim of the study was to review all studies concerning costs of diabetes type 1 and 2 and its complications in old and new EU members. The following countries were taken into account: Slovenia, Poland, Czech Republic, Hungary, Slovakia, Bulgaria, Romania, Lithuania, Latvia and Estonia – as new EU members and remaining EU countries as old members. METHODS: A systematic review of the following databases was conducted: Medline (PubMed), Embase, Cochrane. In addition NICE, INAHTA, HTAI, ISPOR Internet pages were searched. The following key words were used: cost of illness diabetes with name of a country or burden of illness diabetes with name of a country.  Studies’ design, methods, scope and results were compared. Direct and indirect costs were considered separately, detailed costs’ categories and costs related to complications were distinguished. Perspectives, timeframes were taken into consideration and current exchange rates for communication purposes were used. Studies published in English language were included. RESULTS: Only 12 studies concerning cost of diabetes type 1 and 2 and their complications in new EU countries were found as compared to 67 from old EU members. On the side of new EU members one study was found in Lithuania and Bulgaria, 3 in Czech Republic and 7 in Poland. In old EU countries one study was found in Luxembourg and Greece, 2 in Austria, Belgium, Finland and Ireland, 3 in France and Netherlands, 7 in Spain and Italy, 8 in Great Britain, 13 in Sweden and 16 in Germany CONCLUSIONS: Results of this review revealed the necessity of carrying out more studies concerning cost of diabetes and its complications in new EU members.