Gestational diabetes mellitus screening and diagnosis criteria before and during the COVID-19 pandemic: a retrospective pre-post study

Abstract

Objective: To determine whether perinatal outcomes after excluding gestational diabetes mellitus (GDM) on the basis of fasting venous plasma glucose (FVPG) assessment during the coronavirus disease 2019 (COVID-19) pandemic in 2020 were similar to those during the preceding year after excluding GDM using the standard oral glucose tolerance test (OGTT) procedure.

Design: Retrospective pre-post study.

Setting, participants: All women who gave birth in Queensland during 1 July - 31 December 2019 and 1 July - 31 December 2020.

Main outcome measures: Perinatal (maternal and neonatal) outcomes for pregnant women assessed for GDM, by assessment method (2019: OGTT/glycated haemoglobin [HbA_1c ] assessment; 2020: GDM could be excluded by an FVPG value below 4.7 mmol/L).

Results: 3968 of 29 113 pregnant women in Queensland during 1 July - 31 December 2019 (13.6%) were diagnosed with GDM, and 4029 of 28 778 during 1 July - 31 December 2020 (14.0%). In 2020, FVPG assessments established GDM in 216 women (1.1%) and excluded it in 1660 (5.8%). The frequencies of most perinatal outcomes were similar for women without GDM in 2019 and those for whom it was excluded in 2020 on the basis of FVPG values; the exception was caesarean delivery, for which the estimated probability increase in 2020 was 3.9 percentage points (95% credibility interval, 2.2-5.6 percentage points), corresponding to an extra 6.5 caesarean deliveries per 1000 births. The probabilities of several outcomes - respiratory distress, neonatal intensive care or special nursery admission, large for gestational age babies - were about one percentage point higher for women without GDM in 2020 (excluding those diagnosed on the basis of FVPG assessment alone) than for women without GDM in 2019.

Conclusions: Identifying women at low absolute risk of gestational diabetes-related pregnancy complications on the basis of FVPG assessment as an initial step in GDM screening could reduce the burden for pregnant women and save the health system substantial costs.

Keywords: COVID-19; Diabetes, gestational; Diagnostic tests and procedures.