Limiting the Use of Oral Glucose Tolerance Tests to Screen for Hyperglycemia in Pregnancy during Pandemics

Abstract

We aimed to evaluate each proposal of Australian–New Zealand Societies to limit the number of oral glucose tolerance tests (OGTTs) to diagnose hyperglycemia in pregnancy (HIP) during the coronavirus disease 2019 (COVID-19) pandemic. At our university hospital (2012–2016), we retrospectively applied in 4245 women who had OGTT between 22 and 30 weeks of gestation (reference standard: WHO criteria) the proposals in which OGTT is performed only in high-risk women; in all (Option 1) or high-risk (Option 1-Sel) women with fasting plasma glucose (FPG) 4.7–5.0 mmol/L; in all (Option 2) or high-risk (Option 2-Sel) women without history of HIP and with FPG 4.7–5.0 mmol/L. We also tested FPG measurement alone in all high-risk women. Measuring FPG alone had a sensitivity of 49% (95% confidence interval 45–54) applying universal screening. Option 2 appeared to have the best balance considering the needed OGTT (17.3%), sensitivity (72% (67–76)) and rates of a composite outcome (true negative cases: 10.6%, false positive cases: 24.4%; true positive cases: 19.5%; false negative cases: 10.2%). Consideration of a history of HIP and measuring first FPG can avoid more than 80% of OGTTs and identify women with the highest risk of adverse HIP-related events.

Prognosis Associated with Sub-Types of Hyperglycaemia in Pregnancy

“…LGA and small-for-gestational-age were defined as a birth weight greater than the 90th percentile and lower than the 10th percentile for a standard French population, respectively [10,14,21,22]. Preterm birth was defined as occurring before 37 WG and neonatal hypoglycaemia as having at least one blood glucose measurement under 2 mmol/L during the first two days of life.…”

An Update on Screening Strategies for Gestational Diabetes Mellitus: A Narrative Review

“… Seshiah, 2020/India 116 “Single test procedure” for diagnosing GDM: 2h PG ≥ 7.8 mmol/L with 75g oral glucose administered to a pregnant woman in the fasting or non-fasting state, without regard to the time of the last meal (glucose load can also be taken at home and the pregnant woman can visit the hospital 2h after the glucose ingestion to give a single sample for plasma glucose estimation) The economical and evidence based “single test procedure” of DIPSI is most appropriate for screening during COVID-19 as performing OGTTs is resource intensive, the fasting state is impractical with very high dropout rate. Van-de-l’Isle, 2020/UK 121 NICE guidelines methodology (75g 2h OGTT) vs RCOG COVID testing for GDM (two-step testing approach): First, women with risk factors for GDM (according to NICE) are tested with HbA1c and RPG at booking → RPG ≥11.1 mmol/L is diagnostic of T2DM, and HbA1c value of 6.8–7.7% is considered indicative of pre-diabetes (women with a value in this range and a prior history of GDM are managed as GDM) Testing at 28 weeks is recommended and a diagnosis of GDM is made if any of the following criteria were satisfied: FPG ≥5.3 mmol/L or HbA1c ≥ 5.7% or RPG ≥9 mmol/L The overall rate of women identified as having GDM decreased from 7.7% to 4.2% and the COVID-19 regimen failed to detect 57% women identified as GDM Nachtergaele, 2021/France 118 Reference standard testing: OGTT at 22–30 weeks according to IADPSG/WHO criteria applying universal screening Seven tested algorithms (termed as “Options”): OGTT only in women with risk factor for HIP, ie, applying selective screening (Option Sel); OGTT in women with FPG 4.7–5.0 mmol/L at 22–30 weeks, applying universal (Option 1) or selective screening (Option 1-Sel) OGTT in women without history of HIP (previous HIP is considered as GDM) and with FPG 4.7–5.0 mmol/L at 22–30 weeks, applying universal (Option 2) or selective screening (Option 2-Sel) FPG alone measured, applying universal (Option 3) or selective screening (Option 3-Sel) Consideration of a history of HIP and measuring first FPG can avoid more than 80% of OGTTs and identify women with the highest risk of adverse HIP-related events Zhu, 2021 /Australia 120 Initial division into groups according to FPG results (mmol/L): FPG <4.7, FPG 4.7–5.0 and FPG ≥5.1 Division into groups according to how GDM was managed during pregnancy: diet, metformin (MF), insulin and MF + insulin HbA1c and FPG are poor screening tests for GDM. During the COVID-19 pandemic, the OGTT should be given clinical priority in high-risk patients, an HbA1c cut-off of 5.7% is proposed if it is used for screening.…”

“… 117 A French study retrospectively applied in more than 4000 women the seven proposals of the Australian-New Zealand Societies to limit the number of OGTTs during the COVID-19 pandemic. 118 In their cohort, the option in which OGTTs would be performed in women without history of HIP and with FPG 4.7–5.0 mmol/L between 22 and 30 weeks of pregnancy, applying universal screening, was preferred. This approach offered a good compromise because it reduced the rate of women undergoing OGTTs by more than 80%, while identifying around 70% of the women with HIP, especially those with the highest risk of adverse outcomes.…”

HbA1c and fasting plasma glucose cannot replace oral glucose tolerance test in order to screen for hyperglycaemia in pregnancy

“…We had an opportunity to evaluate the sensitivity of the combination of the FPG and HbA 1c to diagnose HIP as proposed by RCOG 1 in our French cohort. [3][4][5] Random plasma glucose was unavailable. In France, we routinely used International Association of Diabetes Pregnancy Study Group (IADPSG)/World Health Organization (WHO) criteria but we retrospectively applied NICE criteria (reference standard).…”