How long after antenatal corticosteroids (Antenatal Corticosteroids) administration can a glucose tolerance test be performed?

From the Guidelines

It is recommended to wait at least 7 days after completing a course of antenatal corticosteroids before performing a glucose tolerance test. Antenatal corticosteroids, such as betamethasone or dexamethasone, are commonly administered to pregnant women at risk of preterm delivery to accelerate fetal lung maturation, but they can temporarily affect maternal glucose metabolism. Corticosteroids cause insulin resistance and can elevate blood glucose levels for several days after administration. This transient hyperglycemic effect typically peaks within 24-48 hours after the last dose and gradually returns to baseline within 5-7 days 1.

The Society for Maternal-Fetal Medicine recommends offering a single course of antenatal corticosteroids to patients who meet specific inclusion criteria, and also suggests consideration for the use of antenatal corticosteroids in select populations not included in the original Antenatal Late Preterm Steroids trial 1. However, the use of antenatal corticosteroids in pregnant patients with pregestational diabetes mellitus is recommended against, given the risk of worsening neonatal hypoglycemia 1.

Performing a glucose tolerance test too soon after corticosteroid administration could lead to falsely elevated results and potentially inappropriate diagnosis of gestational diabetes. For pregnant women who require both antenatal corticosteroids and glucose tolerance testing, it's best to either complete the glucose testing before starting corticosteroids if possible, or postpone it until at least one week after completing the corticosteroid course to ensure accurate results. The immediate risks of late preterm steroids, including neonatal hypoglycemia, should also be considered when making decisions about glucose tolerance testing 1.

Key points to consider when deciding on the timing of glucose tolerance testing after antenatal corticosteroids include:

• The transient hyperglycemic effect of corticosteroids typically peaks within 24-48 hours after the last dose and gradually returns to baseline within 5-7 days
• The risk of falsely elevated results and potentially inappropriate diagnosis of gestational diabetes if glucose tolerance testing is performed too soon after corticosteroid administration
• The importance of considering the individual patient's risk factors and medical history, including pregestational diabetes mellitus, when making decisions about glucose tolerance testing.

From the Research

Timing of Glucose Tolerance Test after Antenatal Corticosteroids

• The ideal time to perform a glucose tolerance test after antenatal corticosteroids administration is a crucial consideration to ensure accurate results and effective management of maternal glycemic status.
• According to a study published in the American Journal of Perinatology 2, the effect of betamethasone on 1-hour glucose screening test results is transient, and it is recommended to postpone the test at least 1 week after betamethasone administration to avoid false-positive results.
• Another study published in Cureus 3 observed that hyperglycemia persisted in 35.71% of participants 1 week after antenatal corticosteroids administration, highlighting the need for close monitoring of blood glucose levels during this period.
• A randomized controlled trial published in Archives of Gynecology and Obstetrics 4 compared the effects of two regimens of antenatal corticosteroids on glycemic control in women with mild gestational diabetes, but did not specifically address the timing of glucose tolerance tests after corticosteroids administration.

Key Findings

• Betamethasone administration can cause transient hyperglycemia, which may lead to false-positive results in glucose screening tests 2.
• The effect of betamethasone on glucose screening test results is significant at 24 hours, but decreases over time, with no significant difference between pre-betamethasone and 1-week post-betamethasone results 2.
• Close monitoring of blood glucose levels is necessary after antenatal corticosteroids administration, regardless of pre-existing glycemic status 3.

Clinical Implications

• Healthcare providers should consider postponing glucose tolerance tests for at least 1 week after antenatal corticosteroids administration to ensure accurate results and avoid unnecessary interventions 2.
• Women who receive antenatal corticosteroids should be closely monitored for hyperglycemia, and their diabetes management plans should be adjusted accordingly 3, 4.