Introduction: In women with gestational diabetes (GDM), 1,5-Anhydroglucitol (1,5-AG) levels are lower compared to controls. However, data on 1,5-AG changes in the postpartum and its associations with indices of insulin secretion or resistance in the perinatal period are lacking. This prospective study assessed the trajectory of 1,5-AG, 1,5-AG/HOMA-IR and 1,5-AG/BMI during pregnancy up to 1-year postpartum, their association with indices of insulin secretion/resistance and whether these indices can predict glucose intolerance (prediabetes and diabetes) at 1-year postpartum in women with GDM.

Methods: We included 211 women with GDM and assessed 1,5-AG levels at 28–32 weeks of gestational age, at 6–8 weeks and at 1-year postpartum. In the context of changing body mass and insulin resistance, we also investigated 1,5-AG/BMI and 1,5-AG/HOMA-IR to adjust for prevailing BMI and HOMA-IR.

Results: Circulating 1,5-AG levels and 1,5-AG/BMI were stable between pregnancy and 6–8 weeks postpartum but increased at 1-year postpartum (p  < 0.001). 1,5-AG/HOMA-IR increased between pregnancy and the early postpartum and stabilized at 1-year postpartum (p  < 0.001). In the perinatal period, 1,5-AG/HOMA-IR was related to a higher insulin-resistance adjusted insulin secretion index (ISSI-2), lower BMI and higher MATSUDA (all p  ≤ 0.001). 1,5-AG/pre-pregnancy BMI during pregnancy and 1,5-AG/HOMA-IR at 6–8 weeks postpartum (both p  ≤ 0.024) predicted a lower risk of glucose intolerance at 1-year postpartum, the latter remained significant after adjusting for HbA1c.

Conclusions: These results suggest that 1,5-AG/HOMA-IR and 1,5-AG/pre-pregnancy BMI change in the perinatal period. They could provide useful information and may serve as markers of future glucose intolerance, and for early risk stratification in women after GDM.

Supplementary information: The online version contains supplementary material available at 10.1007/s40618-025-02768-1.