Association between different response patterns during oral glucose tolerance test and postpartum glucose intolerance in women with gestational diabetes.

Purpose: Our study aimed to assess the associations of the response patterns during gestational oral glucose tolerance test (OGTT) with postpartum glucose intolerance (PGI) in women with gestational diabetes mellitus (GDM).

Methods: This cohort study included 5348 GDM women who underwent the OGTT both 24-28 weeks during pregnancy and 4-12 weeks postpartum from January 2017 to June 2022. Gestational OGTT response patterns included individual time-point glucose values, glucose response trajectories, and GDM subtypes. PGI was defined as women with postpartum pre-diabetes or diabetes. Cox proportional hazards regression models were used to assess the risks of PGI according to different response patterns.

Results: During a median follow-up of 6.3 weeks post-delivery, 1727 (32.3%) women had PGI. Each time-point OGTT glucose were positively associated with PGI. Four OGTT glucose trajectories were fitted: 515 (9.6%) moderate increase following decrease, 557 (10.4%) sustained low-level increase, 3918 (73.3%) moderate increase following slow decrease, and 358 (6.7%) rapid increase following slow decrease. Compared with women with glucose moderate increase following decrease, those with rapid increase following slow decrease had the highest risk of PGI, followed by those with moderate increase following slow decrease. For GDM subtypes, 442 (8.3%) were isolated fasting hyperglycemia (IFH), 4227 (79.0%) were isolated post-load hyperglycemia (IPH), and 679 (12.7%) were combined hyperglycemia (CH). Compared with women with IFH, CH indicated the highest risk of PGI, followed by IPH.

Conclusions: Our findings indicate that distinct OGTT response patterns are associated with varying risks of PGI in women with GDM.