Table 2. Inclusion and exclusion criteria.

Inclusion	Exclusion
Age >18 years	Renal disease
Singleton pregnancy	Chromosomal, genetic or major malformation.
Gestational age 200/7–316/7 weeks	Known fetal aneuploidy based on invasive testing or positive for aneuploidy on cell-free fetal DNA screening.
GDM diagnosis 200/7–316/7 weeks	Contraindication to metformin or insulin
Needs medication (≥30% elevated fasting or postprandial glucose values in the prior week)	Diabetes or GDM <20 weeks or A1c >6.5%
Willingness and ability to attend 2-year follow-up visit	Fasting hyperglycaemia >115 mg/dL (≥50% fasting glucose values in past week)
	Enrolled in a trial that influences the primary study outcome
	Planned delivery at a site without access to the medical record
	Language barrier (appropriate translation resources unavailable at the site)
	Participation in this trial in a previous pregnancy

GDMgestational diabetes mellitus