100-g OGTT found to predict future diabetes risk in pregnant women

100-g OGTT found to predict future diabetes risk in pregnant women | Image Credit: © Chinnapong - © Chinnapong - stock.adobe.com.

The 100-g oral glucose tolerance test (OGTT) has a strong predictive value for diabetes mellitus (DM), according to a recent study published in Pregnancy.¹

Gestational diabetes mellitus (GDM), presenting in an estimated 7.1% of US mothers, has been linked to short- and long-term complications for mothers and infants, especially without interventions. However, recent evidence has indicated glucose challenge tests as potential predictors of long-term abnormalities.²

“Building on these insights, this study aims to explore the association between various abnormal patterns observed in the 100-g OGTT and the subsequent development of DM,” wrote investigators.¹

OGTT classification

The retrospective cohort study included women aged 18 to 45 years undergoing the 100-g OGTT during pregnancy. Singleton and multiple gestations were both included, and investigators defined the OGTT date as the index date. Participants were followed from this date until DM diagnosis, death, or transfer to another health maintenance organization.

Patients with overt DM before the index data, a documented diabetic medication prescription within 3 months before the index date, or missing an OGTT result were excluded from the analysis. Data was obtained from a large health care database and linked using unique encoded identifiers.

Two models were used to analyze data. The first classified OGTT as pathological or normal, with the former defined as 2 or more abnormal values and the latter defined as 0 or 1 abnormal value.

The second model included 5 patient cohorts: 1 abnormal value, 2 abnormal values, 3 abnormal values, 4 abnormal values, and all normal values. A DM diagnosis was defined as the primary outcome of the analysis.

Factors associated with pathological OGTT

There were 7645 women aged a mean of 30.7 years at OGTT and with a mean body mass index (BMI) of 26.16 included in the final analysis. Of these patients, approximately 10% were current smokers, and GDM was reported in 17.3% during follow-up vs DM in 6.4%.

An older age, higher BMI, and increased prevalence of chronic hypertension and hyperlipidemia were reported in patients with pathological OGTT results vs normal OGTT results. DM was reported in 21.6% of patients with at least 2 abnormal OGTT results vs 4.6% in the normal cohort, indicating a hazard ratio (HR) of 2.03.

Investigators noted earlier diabetes diagnosis in the pathological group. Additionally, this population had significantly steeper cumulative probability rates vs the normal OGTT group based on Kaplan–Meier curves.

Increased number of abnormal values linked to higher DM risk

A correlation was found between an increasing number of OGTT values and the prevalence of abnormal lipid metabolism. Patients with a single abnormal value had an HR of 3.2 for future DM, vs 4.89 in those with 2 abnormal values, 8.18 in those with 3, and 15.46 in those with 4.

In a subanalysis evaluating the impact of timing for a single abnormal result, investigators reported an HR of 7.12 for diabetes diagnosis from abnormal fasting glucose. At 1 hour, 2 hours, and 3 hours postglucose ingestion, these HRs were 3.84, 2.15, and 6.03, respectively. An optimal cutoff threshold of 86.5 mg/dL was reported for fasting glucose.

Overall, the data highlighted a strong prognostic value of the 100-g OGTT for predicting DM in pregnant patients. This indicates the tool may be used to identify individuals at high-risk for DM.

“We emphasize that even a single abnormal value—particularly fasting glucose—should prompt clinicians to focus on prevention, allowing for a more personalized approach to care,” wrote investigators.

References

1. Shafran YW, Schiller T, Kirzhner A, Vaisbuch E. Long-term risk prediction of diabetes mellitus using the 100-g oral glucose tolerance test during pregnancy: Insights into test patterns, single abnormal values, and abnormal fasting glucose. Pregnancy. 2025. doi:10.1002/pmf2.70058
2. Hiersch L, Shah BR, Berger H, et al. Oral glucose tolerance test results in pregnancy can be used to individualize the risk of future maternal type 2 diabetes mellitus in women with gestational diabetes mellitus. Diabetes Care. 2021;44(8):1860-1867. doi:10.2337/dc21-0659