A fasting glucose level less than 4.7mmol/L safely screens for gestational diabetes in women, reducing reliance on oral glucose tolerance testing — ASN Events
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A fasting glucose level less than 4.7mmol/L safely screens for gestational diabetes in women, reducing reliance on oral glucose tolerance testing (#106)

Jessica M Deitch 1 2 3 , Dev Kevat 1 2 4 , Christopher J Yates 1 2 , Esha Kathpal 1 , Paul Lawton 1 , Ibrahim Shahid 1 , Shane S Hamblin 1 2 , Balasubramanian Krishnamurthy 1 , Joanne M Said 5 6 7 , Cheryl Steele 1 , I-Lynn Lee 1 2
  1. Department of endocrinology and diabetes, Western Health, Sunshine, Victoria, Australia
  2. Department of Medicine, University of Melbourne, Parkville, VIC, Australia
  3. Department of Endocrinology & Diabetes, Alfred Health, Melbourne, VIC, Australia
  4. Department of obstetric medicine, Western Health, Sunshine, Victoria, Australia
  5. Department of Obstetrics & Gynaecology, Western Health, St Albans, VIC, Australia
  6. Department of Obstetrics, Gynaecology and Newborn Health, University of Melbourne, Parkville, VIC, Australia
  7. Department of Maternal Fetal Medicine, Western Health, St Albans, VIC, Australia

Background/ aims: In an Australian tertiary maternity service, 4650 pregnant women screened for gestational diabetes (GDM) using a COVID-19 simplified screening method with a triaging fasting plasma glucose (FPG) to determine necessity for an oral glucose tolerance test (OGTT) had reduced OGTT requirements by 82.9% and decreased GDM prevalence (18.7% vs 21.7%, p<0.001) with similar perinatal outcomes compared with 7385 women screened with an OGTT pre-pandemic.  This study aimed to further evaluate perinatal outcomes of women with GDM excluded by a FPG <4.7mmol/L (low FPG) alone per simplified screening versus women with a FPG <4.7mmol/L with or without GDM per OGTT.

 

Methods:  A retrospective cohort study included singleton births from 20 weeks’ gestation.  Women who underwent simplified screening (delivered 1st January 2021-31st December 2021) were included if FPG <4.7mmol/L (GDM excluded without an OGTT).  Women screened with a 2-hour 75g OGTT (delivered 1st January 2020-31st July 2021) were included if the fasting glucose was <4.7mmol/L with either normal glucose tolerance (NGT) or GDM (ADIPS 2014 criteria).  Maternal characteristics and perinatal outcomes were compared between groups with additional subgroup analyses per ethnicity performed.

 

Results: 3188 women had a low FPG per simplified screening, 4802 had NGT and 468 had GDM.  The GDM group had more women born in Central/South-East Asia than the low FPG and NGT groups.  Maternal BMI and parity were similar between groups.  The low FPG group had comparable perinatal outcomes to the NGT group.  The GDM group had higher rates of small-for-gestational-age (SGA) infants than the low FPG group (13.5% vs 9.6%, p=0.041).

 

Conclusions:  A FPG <4.7mmol/L safely negated the requirement for an OGTT with no worsening in perinatal outcomes.  The increased SGA infant rate in women diagnosed with GDM on OGTT with a fasting glucose <4.7mmol/L suggests possible overdiagnosis and overtreatment of GDM in this patient population.  These results provide further evidence for the safety of the simplified screening method.  Future randomised trials are required to analyse the effectiveness of screening using an initial triaging FPG.  This could be potentially practice-changing for the general obstetric population and in women who decline or cannot tolerate an OGTT.