Gestational diabetes mellitus (GDM) is a new epidemic among Australian women, especially those with Asian backgrounds. The 1998 Australia National Diabetes Strategy and Implementation Plan recognises GDM as an independent glucose metabolic disorder affecting sub-groups of Australians. Gestational diabetes mellitus is an Australian national diabetes priority area, along with insulin dependent diabetes mellitus (IDDM) and non-insulin dependent diabetes mellitus (NIDDM). This paper reviews the many issues relating to GDM that continue to be debated by researchers and clinical service providers. These issues include the diagnosis of GDM, the effect of GDM on fetal outcomes, the long-term health effects on the offspring of GDM mothers, the effect of GDM on maternal outcomes and the long-term health effects on women with a history of GDM.