Screening for gestational diabetes:comparing NICE criteria versus RCOG criteria recommended during the COVID pandemic-the role of HbAlc in GDM screening

ABSTRACT

Aims: To examine the disparity in identification of gestational diabetes (GDM) using the RCOG criteria (HbAc >39 mmol/mol or FBG >5.6 mmol/L) during the COVID-19 pandemic from the conventional NICE guidelines. Methods: Of 40,740 deliveries at our University Hospital from year 2009 (pre-COVID pandemic) in women without pre-existing diabetes, 8,542 were deemed high-risk based on NICE risk stratifica- VOLUME 21 ISSUE 2 • DECEMBER 2021 293 S tion and had an oral gluose tolerance test (OGTT) for GDM screening. Locally, HbA1c is routinely undertaken along with an OGTT. Data were analysed retrospectively to explore variation in GDM diagnosis using the two criteria. Results: Using NICE criteria and RCOG criteria, 11.3% and 15.3% respectively of 'high-risk' women were diagnosed with GDM. HbA1c ≥39 mmol/mol was observed in 13.5%. When RCOG criteria were used, the diagnosis would have been missed in 43.5% of GDM diagnosed with an OGTT (4.9% of the 'high-risk' cohort;χ2=1423, p<0.001). 8.9% with a normal OGTT would have been diagnosed with GDM with the RCOG criteria. The proportion of Asians was higher in the cohort with HbA1c ≥39 mmol/mol compared with those diagnosed with OGTT alone (26% vs 18%, p<0.001). HbA1c ≥39 mmol/mol was associated with significantly higher fetal macrosomia (birthweight ≥4500 g) compared with GDM diagnosed with OGTT (3.5% vs 0.9%;χ2=47.7, p<0.001), although the women with GDM received intensive antenatal management. Conclusions: The RCOG and NICE criteria, when used in isolation for GDM screening, identify different populations with a risk of missing a GDM diagnosis in a proportion of women when RCOG criteria are solely applied. HbA1c could have a supplementary role when used in addition to OGTT in 'high-risk' women to identify and to potentially reduce maternal-fetal complications through intensive antenatal management.