[CG] Gestational diabetes (GDM), diagnosing, Clyde
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Criteria for diagnosing Gestational Diabetes (GDM) Clyde
At booking: assess for the following risk factors. If one or more is present, check HbA1c and book OGTT at 26 weeks’
- BMI ≥35kg/m2
- Previous baby ≥4.5kg
- Family history of T1 or T2 diabetes in a first degree relative (child, parent,
- 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
- EFW ≥97th 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:
Do not perform OGTT after 35+0 weeks. If there is a clinical concern of GDM at ≥35+0 weeks’ perform a random blood glucose (RBG) and HbA1c. Refer to the DSN/Diabetes Clinic if RBG ≥9mmol/l or HbA1c ≥39mmol/mol.
The utility of OGTT in this cohort of women is unproven but high blood glucoses need to be excluded.