To estimate uptake of the 75 g oral glucose tolerance test (OGTT) at 6–12 weeks postpartum among women with gestational diabetes mellitus (GDM) in Japan, and to explore the demographic and clinical characteristics associated with screening uptake.

Retrospective cohort study using administrative claims data.

Data from a nationwide employees’ health insurance claims database (Japan Medical Data Center; JMDC) during the fiscal years 2012–2020 were assessed.

2282 women with GDM in the JMDC claims database (April 2012–January 2021), ascertained using the International Classification of Diseases 10th revision (ICD-10) codes cross-validated with a high-risk GDM management fee.

Primary outcome: completion of a 75 g OGTT at 6–12 weeks postpartum. Secondary outcomes: completion of a 75 g OGTT at 4–12 weeks postpartum and cumulative completion up to 1 year postpartum.

We included 2282 women in the analysis. The overall screening rate was 28.7% (654/2282) from 2012 to 2020. Even in 2020, the year with the highest reported screening rate, it remained low at 33.2% (181/546). After expanding the range to include 4 weeks to ≤1 year postpartum, the cumulative screening rate reached 64.9% by 1 year postpartum. The screening rate was lower when childbirth and GDM were managed at different facilities than when both were managed within the same facility.

We report suboptimal screening rates for women with a GDM history in Japan. This study highlights the need for continuous monitoring and the development of effective strategies for early screening and intervention in this high-risk group. These strategies should include system-level improvements in screening methods and enhance patient awareness through antenatal education prior to delivery.