Gestational diabetes subtype impacts postpartum prediabetes risk

medwireNews: The risk for postpartum prediabetes varies significantly by gestational diabetes (GD) subtype, with the highest risk observed among women with both postload glucose intolerance (GD-P) and fasting hyperglycemia (GD-F), research suggests.

Julie Van (University of Toronto, Ontario, Canada) and co-investigators say their findings call “for tailored early intervention and postpartum screening strategies by [GD] subtype.”

They explain in JAMA Network Open that although GD subtypes defined during antepartum testing have been linked to adverse perinatal outcomes, little is known about the relationship between GD subtype and maternal metabolic outcomes in the early postpartum period.

To investigate, Van and team analyzed data for 1005 participants (median age 33 years) from the Study of Women, Infant Feeding, and Type 2 Diabetes Mellitus After GD Pregnancy (SWIFT).

All women had GD according to Carpenter–Coustan criteria using the antepartum 3-hour 100-g oral glucose tolerance test (OGTT), with at least two elevated glucose measurements of 95 mg/dL or higher at fasting, and 180 mg/dL or higher at 1 hour, 155 mg/dL or higher at 2 hours, and/or 140 mg/dL or higher at 3-hour postload time points.

They were subgrouped into those with GD-P (at least two elevated postload glucose measurements); GD-F (elevated glucose measurements at fasting and any one postload time point); or both defects (GD-M; elevated glucose at fasting and two or more postload time points).

At 6 to 9 weeks after delivery, prediabetes prevalence, measured using 2-hour, 75-g OGTTs, was 34.5% overall but varied widely among the GD subtypes, the researchers report.

Specifically, 23.9% of the 616 individuals with GD-P had postpartum prediabetes compared with 41.9% of the 124 participants with GD-F, and 55.8% of the 265 individuals with GD-M.

After adjustment for age, race and ethnicity, prepregnancy BMI, educational level, and gestational weight gain, the investigators found that the prevalence of postpartum prediabetes was a significant 1.74- and 2.23-fold higher among the participants with GD-F and GD-M, respectively, relative to those with GD-P.

In addition, the prevalence was a significant 1.28-fold higher in the GD-M group than in the GD-F group.

Van et al note that “[w]omen with GD-F and especially GD-M had higher percentages of obesity and excessive weight gain during pregnancy as well as lower high-density lipoprotein cholesterol, higher triglyceride, and higher leptin levels at 6 to 9 weeks after delivery compared with women with GD-P.”

They continue: “Delivery alone may therefore only minimize but not completely remove the long-standing dysmetabolic state of these subtypes.”

The researchers also found that after adjusting for GD treatment, the prevalence of postpartum prediabetes was similar between the people with GD-F and those with GD-M.

“This finding underscores the importance of early pharmacologic intervention as soon as GD is diagnosed,” they remark, and suggest that women with GD-F and GD-M “may achieve improved glycemic control by combining lifestyle and pharmacologic approaches that improve insulin sensitivity and mitigate obesity.”

The authors conclude that the findings “offer insights for improved risk stratification during the early postpartum period to prioritize longer-term monitoring and early intervention in specific groups of women with GD, with the goal of preventing progression to diabetes after GD pregnancy.”

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JAMA Netw Open 2025; 8: e2542668