Adopting the new World Health Organization diagnostic criteria for gestational diabetes: How the prevalence changes in a high-risk region in Australia

Aims: In this study, we assessed changes in prevalence of gestational diabetes mellitus (GDM) in a region with diverse cultural backgrounds in Australia under the new World Health Organization (WHO) diagnostic criteria, with reference to the woman's ethnicity, age and pre-pregnant body mass index (BMI).

Methods: We recorded results of all 75-gram oral glucose tolerance tests (OGTTs) performed on pregnant women between February and December 2015 together with their demographic details, and determined the prevalence of GDM based on the old Australian Diabetes in Pregnancy Society (ADIPS) and the new WHO criteria respectively.

Results: Over that period, 2140 OGTTs were performed in 1725 pregnant women. The prevalence of GDM was 14.8% (255/1725 women) under old ADIPS criteria, but went up to 29.6% (510/1725) when using WHO criteria. An increase in prevalence was observed in all ethnic groups. Women from East/South-East Asia had the lowest increment (from 19.2 to 22.3%) while those from South Asia had the highest (from 22.0 to 44.4%). Prevalence of GDM was 45.9% amongst women with BMI>30kg/m². For women from South Asia with BMI>30kg/m², 70.0% would have GDM. Birth outcomes were similar between women who would have GDM under WHO but not the old ADIPS criteria (untreated), and those who were treated for GDM under old criteria.

Conclusion: In parts of Australia, adoption of WHO diagnostic criteria could result in doubling of the prevalence of GDM, depending on the women's demographic characteristics. Women from South Asia or those with obesity should be targeted for pre-pregnant lifestyle intervention.