Gestational diabetes mellitus subtypes according to oral glucose tolerance test and pregnancy outcomes

Purpose To determine whether the abnormal glucose concentrations at various oral glucose tolerance test (OGTT) time points are associated with adverse perinatal outcomes in pregnancies complicated by gestational diabetes mellitus (GDM). Methods A retrospective study included 257 pregnant women with GDM (IADPSG criteria) who delivered between 2020-2023 at a tertiary hospital. Women were classified based on their OGTT results: isolated fasting hyperglycemia (group A), isolated post-load hyperglycemia (group B), and combined hyperglycemia (group C). Multivariable linear and logistic regression analyses were performed. Results Most women had fasting hyperglycemia (54.1%), followed by isolated post-load hyperglycemia (29.2%), and combined hyperglycemia (16.7%). In the univariate analysis, women in Groups A and C had higher BMI before pregnancy (29.0 [7.6] kg/m(2) and 30.6 [9.3] kg/m(2), respectively) compared with women in Group B (26.3 [6.2] kg/m2). Groups A and C had a higher prevalence of insulin use compared with Group B (81.3 and 88.4% vs. 49.3%, p < 0.001). Their neonates had higher birth weights (3221 +/- 525 g and 3208 +/- 512 g vs. 3030 +/- 591 g, p = 0.039) and higher rates of large-for-gestational-age (11.5 and 16.3% vs. 2.7%, p = 0.032). However, the multivariable analyses did not show significant differences among the groups. Conclusion The GDM subtypes identified through the OGTT were related to distinct metabolic phenotypes and pregnancy outcomes, indicating the presence of heterogeneity in GDM. Future studies are required to confirm these findings and explore whether the OGTT could be used to guide individualized GDM treatment.