Gestational diabetes mellitus phenotypes defined by 75-g oral glucose tolerance test response patterns: associations with perinatal outcomes and persistent postpartum diabetes.

AIMS: To assess whether 75-g oral glucose tolerance test (OGTT) response patterns define clinically meaningful phenotypes among women with gestational diabetes mellitus (GDM) and whether these phenotypes are associated with perinatal outcomes and persistent postpartum diabetes.

METHODS

This single-center ambispective cohort included women diagnosed with GDM by a 75-g OGTT at 24-28 weeks' gestation (IADPSG) between January 2020 and May 2025. Women were classified as isolated fasting hyperglycemia (Group 1), isolated post-load hyperglycemia (Group 2), or combined hyperglycemia (Group 3). From ≥ 12 weeks postpartum onward, participants were recontacted for assessment of glycemic status, and outcomes were verified using available clinical records, laboratory results when available, and medication data.

RESULTS

Among 251 women (mean age 31.4 years; mean BMI 32.5 kg/m2), insulin therapy was most frequent in Group 3 (27.4%; p < 0.001), which also had higher HbA1c (p = 0.011) and earlier delivery (p = 0.008). Persistent postpartum diabetes occurred in 12%. In multivariable analyses, higher BMI and phenotypes incorporating fasting hyperglycemia (Groups 1/3) were independently associated with persistent postpartum diabetes.

CONCLUSION

OGTT pattern-based phenotyping differentiates GDM subgroups in routine care, with differences in metabolic severity, treatment need, selected perinatal indicators, and postpartum diabetes risk, supporting targeted antenatal management and postpartum follow-up.