There are marked disparities in maternal and infant health in NZ with Maori babies more likely to die than non-Maori babies. Maori women are more likely to have Gestational Diabetes Mellitus (GDM) which is associated with a range of adverse health outcomes including perinatal death. Timely identification and treatment of GDM significantly reduces adverse outcomes, so it is an appropriate condition to examine for possible disparities in care. This study investigates whether Maori women with GDM and their babies have worse health outcomes than non-Maori, and whether they are receiving adequate screening. This retrospective cohort study design draws on birth-related data from two DHB regions over a 15-year period, with additional data obtained via NHI matching from laboratory and nationally held databases. Improving identification and management of GDM in Maori has the potential to reduce harm to mothers and to save babies from both harm and death.