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17-08-2022 | Diabetes | News | Article

Pros and cons with lower vs higher threshold for gestational diabetes diagnosis

Author: Eleanor McDermid

medwireNews: Using the lower IADPSG glycemic criteria rather than the HAPO criteria diagnoses more women with gestational diabetes but does not result in fewer babies being born large for gestational age (LGA), shows a randomized trial.

However, Caroline Crowther (University of Auckland, New Zealand) and co-researchers did find “clinically important” benefits for women with relatively mild gestational diabetes who had access to treatment thanks to their diagnosis based on the IADPSG (International Association of Diabetes in Pregnancy Study Groups).

All the pregnant women participating in the GEMS trial underwent a 2-hour oral glucose tolerance test (OGTT). Of these women, 2022 were randomly assigned to receive a gestational diabetes diagnosis based on the IADPSG criteria, these being fasting plasma glucose of at least 92 mg/dL (≥5.1 mmol/L), 1-hour glucose of at least 180 mg/dL (≥10.0 mmol/L), or 2-hour glucose of at least 153 mg/dL (≥8.5 mmol/L).

This resulted in 15.3% of women being diagnosed with gestational diabetes. They were managed according to local protocols for gestational diabetes and 8.8% went on to have an LGA baby.

A further 2039 women were assessed according to the glycemic criteria used in the HAPO study, so were given a diagnosis if their fasting plasma glucose was at least 99 mg/dL (≥5.5 mmol/L) or their 2-hour glucose was at least 162 mg/L (≥9.0 mmol/L).

Fewer women in this group were diagnosed with gestational diabetes, at just 6.1%, but the rate of LGA birth was almost identical to that seen in the IADPSG criteria group, at 8.9%.

There were no differences in other infant anthropometric measurements. Hypoglycemia was more often identified in infants in the IADPSG group, but the researchers believe this to be because the greater number of women with diagnosed gestational diabetes in this group led to more testing of infants.

“Some infants born to mothers in the higher-glycemic-criteria group may have had undetected hypoglycemia that was not treated,” they write in The New England Journal of Medicine.

“Neonatal hypoglycemia is associated with later adverse neurodevelopment, so follow-up will be needed in order to know whether this detection and treatment lead to later benefits or harms.”

In a predefined subgroup analysis, the team looked at the outcomes of women in both groups whose OGTT results would result in a diagnosis based on the lower but not the higher criteria.

Among these women, being in the IADPSG group (ie, receiving a diagnosis and directed care) was associated with a significantly reduced risk for having an LGA infant relative to being in the HAPO group (6.2 vs 18.0%), as well as for other outcomes including macrosomia and shoulder dystocia. And the women themselves benefitted from the diagnosis, experiencing less gestational weight gain and a lower rate of preeclampsia than those who did not receive a diagnosis.

“The number needed to treat to prevent one large-for-gestational-age infant in this subgroup of women with OGTT results that fell between the lower and higher glycemic criteria was only 4,” say Crowther and team.

They add that further follow-up is needed to see if the improvements for the women and their infants will translate into longer-term health benefits.

medwireNews is an independent medical news service provided by Springer Healthcare Ltd. © 2022 Springer Healthcare Ltd, part of the Springer Nature Group

N Engl J Med 2022; 387: 587–598

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