Over the last 30 years, the management of gestational diabetes mellitus (GDM) has evolved from an almost randomised controlled trial (RCT) “evidence-free” condition, based upon historical, clinical experience, to a much studied, and discussed, clinical entity with varied guidelines around the world. While the guidelines continue to converge, based upon RCTs and robust cohort studies, differences in views on “best practice” remain. The Diabetes and Pregnancy Vitamin D And Lifestyle Intervention for Gestational Diabetes Mellitus Prevention (DALI) studies have now provided insight into reasons why the existing paradigm, that GDM largely commences at 24-28 weeks is seriously flawed. In fact, for many years, studies have shown that GDM diagnosed early in pregnancy is associated with worse outcomes than pregnancies with GDM developing later in pregnancy. Such early, “booking” or “prevalent” GDM is about 15-70% of all GDM1, and a new debate is how its diagnosis should take place. To help address this need, the Treatment Of BOoking Gestational diabetes Mellitus (TOBOGM) study2 is the only RCT of treatment of GDM in early pregnancy that involving masked controls. Participating women have diabetes risk factors and an oral glucose tolerance test (OGTT using WHO criteria) before 20 weeks gestation. Those with GDM by existing criteria (n=800) are randomised to either treatment or a repeat OGTT at 24-28 weeks gestation. Primary outcome is a composite of adverse pregnancy outcomes. A pilot has shown that early treatment may have both benefits and harms3. The results to the TOBOGM study will be presented at the TOBOGM Summit preceding the conference and the findings and their implications discussed. The discussions from the summit will be presented.