Comparison of Universal Screening for Gestational Diabetes Mellitus Between One-step and Two-step Method Among Thai Pregnant Women: A Randomized Control Trial

Aims: To compare the prevalence of GDM and pregnancy outcomes between the one-step and two-step methods of universal screening among Thai pregnant women.

Methods: A randomized controlled trial was conducted on singleton Thai pregnant women at a gestational age of 24-28 weeks. They were randomly assigned to either the one-step method group (a universal 75-gm 2-h oral glucose tolerance test: OGTT) or the two-step method group (a universal 50-gm oral glucose challenge test followed by a 100-gm 3-h OGTT). The women received standard antenatal care. The prevalence of GDM and obstetric outcomes were compared.

Results: A total of 143 women meeting the inclusion criteria were randomly allocated into the one-step group (72 cases) and the two-step group (71 cases). The prevalence of GDM was significantly higher in the one-step group than in the two-step group, with rates of 24/73 (33.3%) vs 8/70 (11.3%); P value 0.002; relative risk of 2.96, 95% CI: 1.43-6.14, respectively. Demographic data and maternal and neonatal outcomes were comparable between the two groups.

Conclusions: The one-step method can markedly increase the prevalence of GDM to nearly three times that of the two-step method, leading to a substantial increase in care costs and burdens without clear benefits. Convincingly, the one-step method as a new approach may not be suitable for universal screening in a busy antenatal care setting, especially in low-resource health centers in developing countries or among populations with a high prevalence of GDM.