RESUMEN
BACKGROUND: Gestational diabetes mellitus (GDM) causes adverse pregnancy outcomes that can be averted by treatment from 24-28 weeks' gestation. Assessing and treating women for overt diabetes in pregnancy (ODIP) at the first antenatal clinic booking is now recommended in international guidelines. As a consequence, women with milder hyperglycaemia are being diagnosed and treated for early GDM, but randomised controlled trial (RCTs) assessing the benefits and harms of such treatment have not been undertaken. The Treatment Of Booking Gestational diabetes Mellitus (TOBOGM) study is a multi-centre RCT examining whether diagnosing and treating GDM diagnosed at booking improves pregnancy outcomes. Methods and analysis: 4000 adult pregnant women (< 20 weeks' gestation) at risk of ODIP will be recruited from 12 hospital antenatal booking clinics and referred for an oral glucose tolerance test (OGTT). 800 women with hyperglycaemia (ie, booking GDM) according to the 2014 Australasian Diabetes-in-Pregnancy Society criteria for pregnant women at 24-28 weeks' gestation will be randomised to immediate treatment for GDM (intervention) or to no treatment (control), pending the results of a second OGTT at 24-28 weeks' gestation. Antenatal and GDM care will otherwise follow local guidelines. Randomisation will be stratified by site and OGTT glycaemic risk strata. The primary pregnancy outcome is a composite of respiratory distress, phototherapy, birth trauma, birth before 37 weeks' gestation, stillbirth or death, shoulder dystocia, and birthweight ≥ 4.5 kg. The primary neonatal outcome is neonatal lean body mass. The primary maternal outcome is pre-eclampsia. Ethics approval: South Western Sydney Local Health District Research and Ethics Office (reference, 15/LPOOL/551). Dissemination of results: Peer-reviewed publications, scientific meetings, collaboration with research groups undertaking comparable studies, discussions with guideline groups and policy makers. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry, ACTRN12616000924459.