Gestational diabetes mellitus (GDM) should be diagnosed on the basis of fasting blood glucose (FBG) levels during the pandemic so that women are not required to spend hours in a testing facility undergoing oral glucose tolerance tests (OGTT), endocrinologists in Queensland say.
Around 80% of pregnancy OGTT tests could be avoided and social distancing maintained if a two-step FBG strategy is used instead during the COVID-19 pandemic, according to clinicians from the Royal Brisbane and Women’s Hospital.
Dr Michael D’Emden and colleagues in the Department of Endocrinology have shown that a GDM screening strategy based on FBG < 4.7mmol/l would have a low rate of abnormal glucose tolerance and minimal adverse pregnancy-associated complications.
They analysed the POGTTs of 26,242 pregnant women in Queensland performed between January and June 2015 and found there were 3,946 (15%) patients having GDM. Of these, 2,262 (8.6%) had FBG ≥ 5.1mmol/l.
In a study published in PLOS One the receiver operator characteristics (ROC) assessment identified FBG levels >4.6mmol/l as having the best specificity (77%) and sensitivity (54%) for elevated one- and/or two-hour blood glucose levels (BGLs).
It found that 73.7% of women had FBG < 4.7mmol/l with a prevalence of GDM of 4.0%, less than one third the overall rate.
Only 4,638 (17.7%) women had indeterminate FBGs from 4.7–5.0mmol/l and would need to consider having a POGTT or undertake alternative strategies to assess glucose tolerance.
“This analysis suggests that a 2-step diagnostic pathway based on an initial FBG can be used to identify women having either “normal” glucose tolerance associated with a low risk in pregnancy-associated adverse outcomes, or women with GDM,” the researchers concluded.
“Importantly, adopting this 2-step approach still enables the effective identification of cases of GDM at increased risk of adverse pregnancy outcomes including those at highest risk having elevated fasting and post-load BGLs”
The study authors said FBG was a simple, inexpensive, reliable and readily understood measurement of glucose, better tolerated than the POGTT, “that can have a role in the assessment of glucose intolerance in pregnancy in the current COVID-19 environment, in health care environments with limited resources and potentially in other clinical circumstances eg patients post bariatric surgery.”
“These data when considered together with the outcome data from a subgroup of HAPO suggests that this two step-diagnostic approach could be considered as a more efficient and cost-effective strategy for the diagnosis of GDM.
“It would significantly reduce the need for a POGGT and avoid labelling 25% of women with a diagnosis of GDM whose pregnancies are not associated with increased rates of adverse outcomes, avoiding providing un-necessary additional resources for education, blood glucose monitoring or therapeutic intervention.”