The clinical and cost effectiveness of tight versus less tight glucose control around the time of birth in pregnancies complicated by gestational diabetes: the GILD trial

QUESTION: In pregnant women/birthing people with gestational diabetes (GDM) around the time of birth, is less tight blood glucose control non-inferior to tight control in relation to neonatal hypoglycaemia? BACKGROUND: GDM affects 8% of UK pregnant women/birthing people (1). South Asian women have a two-fold increased risk, compared to White European women (2). If the mother is hyperglycaemic, placental transfer of glucose leads to fetal hyperglycaemia stimulating fetal hyperinsulinism. At birth, placental supply of glucose is cut-off; persistent high insulin levels can cause neonatal hypoglycaemia. Maintaining stable maternal intrapartum blood glucose could prevent this. Neonatal hypoglycaemia occurs in 7-20% of babies born to women with GDM (5, 6) and around 10% of babies are admitted to the Neonatal Unit. Severe or prolonged hypoglycaemia can cause seizures, brain damage and death. ‘Tight’ maternal glucose control during pregnancy could reduce adverse maternal/baby outcomes (4) but evidence on whether intrapartum tight glucose control is beneficial is lacking (5). Despite no RCT evidence, some now advocate for less tight control during labour (6). Tight control, and therefore greater use of insulin to reduce blood glucose levels can lead to maternal hypoglycaemia in GDM women (2-28%) (4). The need for insulin requires an IV line and restricts movement in labour. Women/birthing people say tight control negatively impacts birth experience. OBJECTIVES 1.To establish whether less tight blood glucose control is non inferior to tight control around the time of birth for women with GDM for risk of neonatal hypoglycaemia and neonatal unit admission 2. To investigate benefits/harms of less tight control compared to tight control in other maternal/neonatal outcomes 3. To undertake an economic evaluation 4.To conduct an internal pilot phase to inform progression to main trial 5.To assess the acceptability of less tight or tight control, for women and health professionals (HCPs), by conducting a qualitative sub-study 6.To conduct a Study Within a Trial to evaluate an ‘inclusivity package’, to increase participation of South Asian women METHODS: Multi-centre, open-label, randomised, two-arm parallel group, non-inferiority trial, with internal pilot phase, and economic and qualitative evaluation. Conducted in 23 UK hospitals in areas of high ethnic and socioeconomic diversity. GDM women/birthing people approached between 28+0-36+6 weeks’ gestation (routine antenatal care). Written informed consent at 36 weeks’ gestation and continuous glucose monitor (CGM) fitted at 37-38 weeks, to facilitate real-time trial data collection. 1630 women/birthing people randomised via a web-system at 37 weeks. To determine acceptability of less tight glucose control, women/birthing people and HCPs will be interviewed. An economic evaluation will be undertaken. TIMELINES: Total 40 months. 1-9 set-up, 10-27 recruitment, 19 internal pilot, 31 finish data collection, 35-40 reporting/dissemination. IMPACT: If less tight glucose control is non inferior to tight control AND acceptable to HCPs and pregnant women/birthing people, it is highly likely to be introduced NHS-wide, reducing midwifery workload and improving birth experiences. DISSEMINATION: Published monograph, research papers and presentations at clinical conferences. Findings available to study participants/wider public via PPI partners, lay summaries, infographics, animations and videos.