Purpose and Objectives The objective of our study was to model the costs and benefits of 2 screening criteria for people with gestational diabetes. Because people with a history of gestational diabetes are at increased risk for type 2 diabetes, we modeled the effects of a postdelivery intervention based on the Diabetes Prevention Program, which is offered to all people with a history of gestational diabetes defined by either set of criteria. Intervention Approach We used a probabilistic decision tree model to compare the costeffectiveness of the International Association of Diabetes in Pregnancy Study Group's (IADPSG's) screening criteria and the Carpenter-Coustan screening criteria for gestational diabetes through delivery and a follow-up period during which people might develop type 2 diabetes after pregnancy. Evaluation Methods The model included perinatal outcomes for the infant and mother and a 10- year postdelivery period to model maternal progression to type 2 diabetes. The model assumed the health care system perspective. People with gestational diabetes received treatment for gestational diabetes during pregnancy, and we assumed that 10% would participate in a Diabetes Prevention Program-based postdelivery intervention to reduce the risk of type 2 diabetes. We estimated the cost-effectiveness of each screening strategy in qualityadjusted life-years (QALYs) in 2022 dollars. Results At 10% participation in a Diabetes Prevention Program-based postdelivery intervention, the Carpenter- Coustan criteria were cost-effective, compared with no screening ($66,085 per QALY). The IADPSG screening criteria were slightly less cost-effective, c o m p a r e d w i t h n o s c r e e n i n g ( $ 9 7, 8 7 8 p e r Q A L Y) o r Carpenter-Coustan screening criteria ($122,279 per QALY). With participation rates of 23% or higher, the IADPSG screening criteria were highly cost-effective ($48,588 per QALY), compared with Carpenter-Coustan screening criteria. Implications for Public Health Diagnosing a larger proportion of pregnant people using the IADPSG screening criteria, compared with using Carpenter-Coustan screening criteria, is not cost-effective at low levels of participation. However, with moderate levels of participation (23%) in a Diabetes Prevention Program-based postdelivery intervention, the expanded IADPSG screening criteria are cost-effective and reach up to 4 times as many people as Carpenter-Coustan screening.