High prevalence of early (1st trimester) gestational diabetes mellitus in Polish women is accompanied by insulin resistance similar to women with polycystic ovary syndrome (PCOS).

Depending on the choice of IR indices healthy 1st trimester pregnant women demonstrate either similar, or greater IR than women with PCOS and this is accompanied by high prevalence of early GDM. It remains to be established whether GDM screening should be performed in the 1st trimester.