Glycaemic control in labour with diabetes: GILD, a scoping study.

Background: Diabetes in pregnancy is common, affecting 5-10% of pregnant women. Poor glycaemic control in labour is associated with neonatal hypoglycaemia and other adverse outcomes for mother and baby, but tight glucose control is burdensome, intrusive and may not always be necessary. The ideal intrapartum glucose target level is unknown, traditionally 'tight' control (target 4-7 mmol/l) has been recommended; however, this increases the risk of maternal hypoglycaemia.

Objective: To determine the feasibility of a randomised clinical trial to compare clinical and cost-effectiveness of permissive versus intensive intrapartum glycaemic control in labour in pregnancies complicated by diabetes.

Design: A mixed-methods study including audit of clinical guidelines from United Kingdom maternity units, online surveys of women with diabetes and healthcare professionals, service evaluation of intrapartum glycaemic care, Delphi survey and consensus meeting. Data from these work packages led to the design of a clinical trial, and qualitative interviews were held to understand acceptability of the trial.

Setting: National Health Service maternity services and online input from service users.

Participants: Healthcare professionals and women with type 1 or type 2 diabetes mellitus or gestational diabetes (currently pregnant or having birthed after active labour in past 3 years).

Results: There is significant variation in the recommended frequency of testing for gestational diabetes in labour, technologies used to test glucose levels in labour and administer insulin in type 1 diabetes mellitus, and in how neonatal hypoglycaemia is defined. Of surveyed women, 66% would be willing to participate in a future trial, with 23% unsure without further information. The service evaluation showed that once glucose testing had commenced, it was repeated after 1 hour in 18%, 2 hours in 38% and 4 hours in 45% of women. Neonatal hypoglycaemia was considered the most important neonatal outcome for a future trial, with maternal satisfaction the most important maternal outcome. The incidence of neonatal hypoglycaemia (defined as glucose < 2.6 mmol/l) was 47% in type 1 diabetes mellitus, 45% in type 2 diabetes mellitus and 16% in gestational diabetes mellitus. A non-inferiority trial to compare permissive versus intensive glucose control was designed to include all types of diabetes in an umbrella trial (conduct more than one trial simultaneously). Women and healthcare professionals considered the trial design acceptable and feasible, though noted important considerations in the design and conduct.

Limitations: Glucose levels may be poorly recorded in maternity notes and in practice tested more frequently than the study suggests. Sample sizes in some of the work packages were smaller than our pre-specified target, attrition in the Delphi survey was greater than anticipated and the study was conducted during the COVID-19 pandemic impacting results. Willingness to participate in a hypothetical trial might not translate into recruitment to a real trial.

Conclusions: An umbrella trial using a master protocol was designed to compare tight glycaemic control (standard care) with more permissive control in all types of diabetes. Such a trial is feasible and acceptable to women with lived experience of diabetes during pregnancy and by the women and healthcare professionals who took part in qualitative interviews.

Future work: We recommend that a future randomised trial should include an internal pilot phase to test key aspects of trial conduct and clear progression criteria, given the challenges we have identified during this scoping study.

Study registration: This study is registered as researchregistry6832.

Funding: This award was funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme (NIHR award ref: NIHR130175) and is published in full in Health Technology Assessment; Vol. 29, No. 41. See the NIHR Funding and Awards website for further award information.