Clinical Care and Education Oral Abstract Presentations

DC2439 - A1c versus Oral Glucose Tolerance Test for Chronic Glycemic Surveillance in Women with Previous Gestational Diabetes

Thursday, November 21, 2024

14:00 - 15:15 AT Time

Location: Room 201

Presenter(s)

Ravi Retnakaran, MD

Professor of Medicine, Clinician-Scientist
Mount Sinai Hospital
University of Toronto, Mount Sinai Hospital
Toronto, Ontario, Canada

Disclosure(s): Boehringer Ingelheim: Grant/Research Support (Ongoing); Eli Lilly & Company: Consultant (Ongoing); Novo Nordisk: Consultant (Ongoing), Grant/Research Support (Ongoing); Sanofi: Consultant (Ongoing)

Blinded Abstract:

Objective: Women with gestational diabetes (GDM) are advised to undergo an oral glucose tolerance test (OGTT) within 6-months postpartum, owing to their elevated risk of developing pre-diabetes/diabetes. However, the optimal approach to glycemic surveillance in the years thereafter is unclear. We thus sought to compare OGTT and A1c for chronic monitoring of women with previous GDM.

Methods: At both 3-years and 5-years postpartum, 111 women with previous GDM underwent A1c measurement and OGTT, enabling assessment of insulin sensitivity/resistance (Matsuda index, HOMA-IR) and beta-cell function (Insulin Secretion-Sensitivity Index-2 (ISSI-2), insulinogenic index/HOMA-IR (IGI/HOMA-IR)).

Results: At 3-years, dysglycemia (pre-diabetes/diabetes) was diagnosed in 10 women by A1c alone, 24 women by OGTT alone, and 16 women by both A1c and OGTT. Beta-cell function progressively worsened from those diagnosed by A1c alone to OGTT alone to those meeting both criteria (ISSI-2: p< 0.001; IGI/HOMA-IR: p=0.01). At 5-years, dysglycemia was diagnosed in 13 women by A1c alone, 27 by OGTT alone, and 21 by both measures. Beta-cell function again progressively decreased from A1c alone to OGTT alone to both (ISSI-2: p< 0.001; IGI/HOMA-IR: p< 0.001) but was now accompanied by worsening insulin resistance (Matsuda index: p< 0.001; HOMA-IR: p=0.002) and rising fasting glucose (p=0.008) across the groups.

Conclusion: In women with previous GDM, dysglycemia on OGTT identifies a higher risk metabolic phenotype than when diagnosed by A1c, suggestive of more robust glycemic surveillance by OGTT.