Table 1.

Current and modified GDM diagnostic approaches in UK, Canada and Australia, with description of the specific diagnostic approaches evaulated in this paper.

Country	A) Current process and criteria for GDM diagnosis	B) Modified GDM diagnostic approach during COVID-19 pandemic	C) Post-COVID approach tested in current paper
United Kingdom (1)(published)	•Risk factor based testing •75 g OGTT •GDM if FVPG ≥ 5.6 mmol/L and/or 2 h VPG ≥ 7.8 mmol/L	•Risk factor based testing •No OGTT •GDM if HbA1c ≥ 5.7% (39 mmol/mol) and/or FVPG ≥ 5.6 mmol/L and/or Random VPG (not preferred) ≥ 9.0 mmol/L	•Universal fasting glucose and HbA1c •GDM if HbA1c ≥ 5.7% (39 mmol/mol) and/or OGTT FVPG ≥ 5.6 mmol/L
Canada (2)(published)	•Universal screening with 50 g glucose challenge •Diagnostic 75 g OGTT if 1 hr VPG 7.8 – 11.0 mmol/L •Preferred criteria: GDM if Fasting VPG ≥ 5.3 mmol/L and/or 1 h VPG ≥ 10.6 mmol/L and/or 2 h VPG ≥ 9.0 mmol/L	•Universal testing •No OGTT •GDM if HbA1c ≥ 5.7% (39 mmol/mol) and/or Random VPG ≥ 11.1 mmol/L	•Universal testing •No OGTT •GDM if HbA1c ≥ 5.7% (39 mmol/mol)
Australia (3)(published)	•Universal 75 g OGTT •GDM if Fasting VPG ≥ 5.1 mmol/L and/or 1 h VPG ≥ 10.0 mmol/L and/or 2 h VPG ≥ 8.5 mmol/L	•Universal testing •Initial Fasting VPG •Fasting VPG < 4.7 mmol/L → normal •Fasting VPG 4.7 – 5.0 mmol/L → for OGTT, GDM criteria as noted •Fasting VPG ≥ 5.1 mmol/L → GDM	•Universal testing •Initial Fasting VPG •Fasting VPG < 4.7 mmol/L → normal •Fasting VPG 4.7 – 5.0 mmol/L → for OGTT, GDM criteria as per current process •Fasting VPG ≥ 5.1 mmol/L → GDM

Comparison of (A) Current GDM diagnostic processes and criteria, (B) Proposed modified approach during the COVID-19 pandemic and (C) Approach tested for each country in the current paper.

GDM gestational diabetes mellitus; COVID coronavirus disease; OGTT oral glucose tolerance test; FVPG fasting venous plasma glucose; VPG venous plasma glucose