Gestational diabetes mellitus testing in the COVID-19 pandemic: The problems with simplifying the diagnostic process

Abstract

Background: Multiple professional bodies have temporarily revised recommendations for gestational diabetes mellitus (GDM) testing during the COVID-19 pandemic to reduce person-to-person contact. The current Australian temporary criteria advise that if the fasting glucose is ≤4.6 mmol/L, then no glucose tolerance test (GTT) is required. Aims: The aim of this study is to examine the extent of underdiagnosis of GDM using a fasting glucose ≤4.6 mmol/L as a cut-off to determine that a GTT is not necessary. Materials and Methods: De-identified data from pregnant women having a GTT test in the Illawarra area during a six-year period was used to determine the number of women with GDM and the proportion of positive cases that would be missed for different fasting glucose values. Results: There were 16 522 results identified and GDM was diagnosed in 12.2%. The majority of women were more than 30 years of age (85.2%) and diagnosed at ≥20 weeks gestation (81.1%). Of those diagnosed with GDM, 29% had a fasting glucose of ≤4.6 mmol/L and would have been missed. Conclusions: Our results show that using a fasting glucose of 4.6 mmol/L or less would miss nearly a third of women who would otherwise be diagnosed with GDM.