Since 2008 there have been screened all pregnant women for gestational diabetes in the Czech Republic. Nevertheless since 2014 the results of the oral glucose tolerance test (which is a part of the screening) have been evaluated by two different sets of diagnostic criteria. While diabetologists as well as biochemists newly use the criteria recommended by the International Association of Diabetes and Pregnancy Study Groups (IADPSG), accepted by various national medical societies and WHO in 2013 as well, czech gynecologists still use the former criteria accepted in 2008. In the article we analyse the most important arguments against the new criteria and explain the importance of unified methods of screening and follow-up of gestational diabetes (GDM).