Background: Gestational diabetes mellitus (GDM) is increasing and is a risk for type 2 diabetes. Evidence supporting screening comes mostly from high-income countries. We aimed to determine prevalence and outcomes in urban Viet Nam. We compared the proposed International Association of the Diabetes and Pregnancy Study Groups (IADPSG) criterion, requiring one positive value on the 75-g glucose tolerance test, to the 2010 American Diabetes Association (ADA) criterion, requiring two positive values.
Methods and findings: We conducted a prospective cohort study in Ho Chi Minh City, Viet Nam. Study participants were 2,772 women undergoing routine prenatal care who underwent a 75-g glucose tolerance test and interview around 28 (range 24-32) wk. GDM diagnosed by the ADA criterion was treated by local protocol. Women with GDM by the IADPSG criterion but not the ADA criterion were termed "borderline" and received standard care. 2,702 women (97.5% of cohort) were followed until discharge after delivery. GDM was diagnosed in 164 participants (6.1%) by the ADA criterion, 550 (20.3%) by the IADPSG criterion. Mean body mass index was 20.45 kg/m(2) in women with out GDM, 21.10 in women with borderline GDM, and 21.81 in women with GDM, p<0.001. Women with GDM and borderline GDM were more likely to deliver preterm, with adjusted odds ratios (aORs) of 1.49 (95% CI 1.16-1.91) and 1.52 (1.03-2.24), respectively. They were more likely to have clinical neonatal hypoglycaemia, aORs of 4.94 (3.41-7.14) and 3.34 (1.41-7.89), respectively. For large for gestational age, the aORs were 1.16 (0.93-1.45) and 1.31 (0.96-1.79), respectively. There was no significant difference in large for gestational age, death, severe birth trauma, or maternal morbidity between the groups. Women with GDM underwent more labour inductions, aOR 1.51 (1.08-2.11).
Conclusions: Choice of criterion greatly affects GDM prevalence in Viet Nam. Women with GDM by the IADPSG criterion were at risk of preterm delivery and neonatal hypoglycaemia, although this criterion resulted in 20% of pregnant women being positive for GDM. The ability to cope with such a large number of cases and prevent associated adverse outcomes needs to be demonstrated before recommending widespread screening. Please see later in the article for the Editors' Summary.