Background: Gestational diabetes mellitus (GDM) causes adverse pregnancy outcomes which are reduced with treatment from 24-28 weeks gestation. Testing women for overt diabetes-in-pregnancy at antenatal clinic booking is now recommended, increasing the number of women treated for early GDM, but without randomised controlled trial (RCT) evidence of benefit and potential for harm. TOBOGM is a multicentre RCT testing whether treating ‘GDM’ from booking reduces adverse pregnancy outcomes.
Methods and analysis: 'At risk' women <20 weeks gestation (n=4000) are recruited from the antenatal booking clinic across 12 hospitals and referred for an early oral glucose tolerance test (OGTT). Women with GDM by the 2014 ADIPS criteria (n=800) will be randomised to either immediate referral for GDM management or to defer treatment with a repeat OGTT at 24-28 weeks (along with women without GDM-‘decoys’). Randomisation is stratified by site and by higher and lower OGTT glycaemic strata. Primary neonatal outcome for assessing benefit of treatment of Booking GDM is a composite of, respiratory distress, phototherapy, birth trauma, preterm birth <37 weeks, stillbirth/death, shoulder dystocia or birthweight ≥4.5kg. Primary neonatal outcome for assessing harm is reduction of neonatal lean body mass. Primary maternal outcome is pre-eclampsia.
Pilot Study results: Exclusions included gestation ³ 20/40 (48%), refused (5%), prior testing/refused OGTT (13%), no risk factors (16%). Overall 100/607 women consented but 28/100 were withdrawn (eg no OGTT). Gestation on entry was 17±2 weeks. There were 20/72 (28%) with Booking GDM. Of 10 randomised to treatment deferral, 1 withdrew, but 8/9 (89%) still had GDM at the 24-28 week OGTT. Neonatal hypoglycaemia (<2.6 mmol/l) was present in 22%/25%/21% of women in treated/deferred treatment/decoy groups.
Conclusions: An RCT of treating booking GDM is feasible. Most women with booking GDM, still have GDM at 24-28 weeks. The main TOBOGM RCT is now underway
Trial registration: ACTRN12616000924459