Aims/hypothesis: The aim of this systematic review was to develop core outcome sets (COSs) for trials evaluating interventions for the prevention or treatment of gestational diabetes mellitus (GDM). Methods: We identified previously reported outcomes through a systematic review of the literature. These outcomes were presented to key stakeholders (including patient representatives, researchers and clinicians) for prioritisation using a three-round, e-Delphi study. A priori consensus criteria informed which outcomes were brought forward for discussion at a face-to-face consensus meeting where the COS was finalised. Results: Our review identified 74 GDM prevention and 116 GDM treatment outcomes, which were presented to stakeholders in round 1 of the e-Delphi study. Round 1 was completed by 173 stakeholders, 70% (121/173) of whom went on to complete round 2; 84% (102/121) of round 2 responders completed round 3. Twenty-two GDM prevention outcomes and 30 GDM treatment outcomes were discussed at the consensus meeting. Owing to significant overlap between included prevention and treatment outcomes, consensus meeting stakeholders agreed to develop a single prevention/treatment COS. Fourteen outcomes were included in the final COS. These consisted of six maternal outcomes (GDM diagnosis, adherence to the intervention, hypertensive disorders of pregnancy, requirement and type of pharmacological therapy for hyperglycaemia, gestational weight gain and mode of birth) and eight neonatal outcomes (birthweight, large for gestational age, small for gestational age, gestational age at birth, preterm birth, neonatal hypoglycaemia, neonatal death and stillbirth). Conclusions/interpretation: This COS will enable future GDM prevention and treatment trials to measure similar outcomes that matter to stakeholders and facilitate comparison and combination of these studies. Trial registration: This study was registered prospectively with the Core Outcome Measures in Effectiveness Trials (COMET) database:

Clinical diabetes, Core outcome set, Insulin therapy, Pregnancy, Systematic review,
Diabetologia: clinical and experimental diabetes and metabolism
Department of Gynaecology & Obstetrics

Egan, A.M. (Aoife M.), Bogdanet, D. (Delia), Griffin, T.P. (Tomás P.), Kgosidialwa, O. (Oratile), Cervar-Zivkovic, M. (Mila), Dempsey, E. (Eugene), … Dunne, F. (2020). A core outcome set for studies of gestational diabetes mellitus prevention and treatment. Diabetologia: clinical and experimental diabetes and metabolism. doi:10.1007/s00125-020-05123-6