Gestational diabetes (GDM), diagnosing, QEUH, Obstetrics

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Criteria for diagnosing Gestational Diabetes (GDM) QEUH

At booking: assess for the following risk factors. If one or more is present, check
HbA1c and book OGTT at 26 weeks’

  • BMI ≥40kg/m2
  • Previous baby ≥4.5kg
  • Family history of T1 or T2 diabetes in a first degree relative (child, parent,
    brother, sister)
  • Family origin: South Asian, Middle Eastern, Chinese or Black African/ Caribbean
  • Previous pancreatitis
  • Previous gestational diabetes (book OGTT at 16 and 26 weeks’)

Result of HbA1c taken at booking:

  • If ≥ 48mmol/mol refer directly to the diabetes antenatal clinic
  • If < 48mmol/mol perform OGTT at 26 weeks’ gestation (NB if previous GDM for OGTT at 16 weeks’ also)

During pregnancy: arrange OGTT if any of the clinical factors below are present:

  • glycosuria of 2+ or above on 1 occasion
  • glycosuria of 1+ or above on 2 or more occasions
  • Polyhydramnios
  • EFW ≥95th centile

Escalation of OGTT result:

If fasting blood glucose (FBG) ≥7.0mmol/l and/or 2hr blood glucose ≥ 11.0mol/l,
refer immediately to the local Diabetes Specialist Nurse. This applies at any
gestational age and women should be seen urgently.

End date for OGTT:

  • Perform OGTT until 36+6 weeks’. If GDM confirmed, DCU to provide meter and refer to next DM ANC (force book if required).

Clinical concern of GDM >37 weeks’:

  • Do not perform OGT but refer to DCU. Provide glucose meter, BG targets and DSN contact details (if advice needed prior to clinic review with booking
    consultant).
  • Arrange appointment with booking consultant within that week to make a delivery plan (force book if required).
  • Consider VRIII in labour, neonatal hypoglycaemia plan and request maternal post-natal HbA1c via GP at 3 months.
  • If DSN, Obstetric Cons or MW has concerns about BG levels, email rahat.maitland@ggc.scot.nhs.uk for advice.

OGTT is positive for GDM if FBG ≥5.1mmol/l and/or 2-h BG ≥8.5mmol/l

Last reviewed: 21 November 2021

Next review: 30 April 2022

Author(s): Rahat Maitland

Version: 2

Approved By: Obstetrics Clinical Governance Group

Document Id: 884