New aspects in the diagnostics and therapy of diabetes mellitus and IFCC Global Campaign on diabetes seem to be resources for changes in laboratory and clinical practice. The main changes comprise assessment of glucose in venous plasma, strict recommendations for preanalytical phase, two-hour glucose as the main value in oral glucose tolerance test (oGTT), improved cut-off values, withdrawal of O’Sullivan test (50 g glucose) and withdrawal of 100 g glucose during oGTT in pregnant women and other changes. Due to these facts algorithms for the diagnostics of diabetes mellitus in adults and gestational diabetes mellitus are presented with respect to the recommendation of national scientific societies. Remarks to the methodology for the assessment of diabetes mellitus compensation are added.

        Key words: diabetes mellitus, gestational diabetes mellitus, oral glucose tolerance test, hemoglobin A1c.