Changing the protocol for gestational diabetes mellitus screening

Gestational diabetes mellitus (GDM) affects 5-8% of pregnant women in Australia and is linked to adverse maternal and neonatal outcomes. Earlier diagnosis and treatment has been suggested to improve these outcomes.

To describe the experience of a change in GDM screening policy at a large tertiary hospital.

A 6-month audit was performed following a policy change involving introduction of screening for all women early in pregnancy (by either random blood glucose level (BGL) or oral glucose tolerance testing (OGTT), depending on their perceived risk of developing GDM), followed by universal OGTT at 26-28 weeks' gestation. The prevalence of GDM (including changes expected from new Australasian Diabetes in Pregnancy Society (ADIPS) criteria), maternal and neonatal outcomes and adherence to new screening policy are reported.

The prevalence of GDM was 7.9% (1.6% early, 6.3% later diagnoses). More women with early diagnoses required insulin. Early testing with random BGL for low-risk women only identified 1.7% of those with GDM. Early OGTT for high-risk women identified 24.9% of GDM diagnoses. Adherence to the new screening protocol was generally poor, with 26% adherence at booking, 64% at 26 weeks' gestation and 27% with unknown GDM status.

While early testing with OGTT for high-risk women may be helpful, the value of early testing with random BGL for low-risk women is questionable. The new ADIPS criteria are likely to increase the number of women diagnosed with GDM (with an emphasis on earlier diagnosis), but the absolute increase remains small.