The treatment of booking gestational diabetes mellitus (TOBOGM) pilot randomised controlled trial

Background: We piloted a randomised controlled trial (RCT) comparing pregnancy outcomes among women with booking gestational diabetes (GDM) receiving immediate or deferred treatment. Methods: Consecutive, consenting women < 20 weeks gestation, with GDM risk factors attending the hospital book-in clinic, completed an oral glucose tolerance test (OGTT). Clinicians were blinded to OGTT results. Women fulfilling World Health Organisation GDM criteria were randomised to either clinic referral /ongoing treatment (Treated Group n = 11), or no treatment (No Treatment Group n = 10). Women without ‘Booking GDM’ (‘Decoys’ n = 58) and those in the No Treatment Group had a repeat OGTT at 24–28 weeks (with GDM treated if diagnosed). Midwives and mothers were asked to complete surveys and attend focus groups before and after the study respectively regarding their experiences and expectations of the study protocol. Results: Sufficient women completed each step of the RCT. Gestation at OGTT was late at 18 ± 2 weeks with Treated and No Treatment groups largely similar. At 24–28 weeks gestation, GDM was present in 8/9 (89%) in the No Treatment group and 11/56 (20%) Decoys. NICU admission was highest in the Treated group (36% vs 0% p = 0.043), largely due to small for gestational age, and Large for Gestational Age babies greatest in the No Treatment group (0% vs 33% p = 0.030). Conclusion: An RCT deferring ‘Booking GDM’ treatment is feasible. Most women with untreated ‘Booking GDM’ in mid 2nd trimester had GDM at 24–28 weeks. Early treatment may have both benefits and harms. A full RCT is needed.