Table 3.

Guidelines for diagnosis of GDM proposed during the COVID-19 pandemic. OGTT = Oral Glucose Tolerance Test; FPG = fasting plasma glucose; HbA1c = glycated haemoglobin; LGA = large-for-gestational-age; GDM = gestational diabetes mellitus; US = ultrasound; RPG = random plasma glucose; T2DM = Type 2 diabetes mellitus.

Gestation	Screening details	Guidelines, by nation
		Australia [36,37]	Canada [38]	Japan [25]	France [39]	UK[40]
12 weeks	Screening strategy	Risk factor screening = HbA1c in first trimester	Pregnant people at risk of overt diabetes = HbA1c or FPG		Risk factor screening = FPG	At booking for high-risk: HbA1c and RPG
	Thresholds for diagnosis	HbA1c >5.9% (41 mmol/mol)	HbA1c ≥6.5% (48 mmol/mol) or FPG ≥7.0 mmol/L [41]		GDM = FPG 5.1–6.9 mmol/L T2DM = FPG ≥7.0 mmol/L	GDM = HbA1c 5.9–6.5% (41–48 mmol/mol) or RPG 9–11 mmol/L T2DM = HbA1c ≥ 6.5% (48 mmol/mol) or RPG >11.1 mmol/l
28 weeks	Screening strategy	Universal OGTT or FPG	Universal Standard protocol or HbA1c or RPG	Universal HbA1c or RPG or FPG	Selective Standard protocol or HbA1c or FPG	Selective HbA1c or RPG or FPG
	Thresholds for diagnosis of GDM	Standard OGTT thresholds Or Not GDM = FPG ≤4.6 mmol/L Refer OGTT = FPG 4.7–5.0 mmol/L GDM = ≥5.1 mmol/L	Standard = 50 g GCT, if 7.8–11.0 mmol/L then 75 g OGTT Or HbA1c ≥5.7% (39 mmol/mol) or RPG ≥11.1 mmol/l	HbA1c ≥5.7% (39 mmol/mol) Or RPG ≥ 9.0 mmol/L Or FPG ≥ 5.1 mmol/L	HbA1c ≥5.7% (39 mmol/mol) Or FPG ≥5.1 mmol/L	HbA1c ≥5.7% (39 mmol/mol) Or RPG ≥9.0 mmol/L Or FPG ≥5.6 mmol/L If resources allow: FPG ≥5.3 mmol/L
	Recommendations for other testing				Macrosomia or hydramnios = FPG and HbA1c and/or self-monitoring of blood glucose	Heavy glycosuria, high clinical suspicion of diabetes, LGA or polyhydramnios on US tested for GDM at any pregnancy stage