Nearly one third of gestational diabetes mellitus (GDM) cases could be missed because of COVID-19 precautions that have aimed to minimise face-to-face contact for screening, endocrinologists say.

Peak diabetes groups issued emergency guidelines in April recommending different approaches depending on pathology centres’ capacity for physical distancing and the risk of community transmission.

Now, a study of pathology data over six years suggests about 29% of women with a fasting glucose level equal to or under 4.6mmol/L may have been missed, potentially increasing their risk of adverse pregnancy outcomes.

Under the pandemic guidance issued by groups including the Australian Diabetes in Pregnancy Society, at a moderate or ‘amber’ level of COVID-19 risk, women at 24-28 weeks gestation with a fasting glucose level at or under <4.6mmol/L were not recommended to have a glucose tolerance test (GTT).