Is 1-Hour Glucose Screening Test Reliable after a Short-Term Administration of Antenatal Betamethasone?

This study was designed to determine whether betamethasone has any effect on 1-hour (50-g) glucose screening test in nongestational diabetic pregnancy, and if any exists, to determine if this effect is transient or permenant. If the effect is temporary, the study was designed to determine the duration of this glucose intolerance effect and to determine the timing of 1-hour glucose screening test after betamethasone usage. One hundered fourteen pregnant women with a diagnosis of preterm labor at 24 to 34 weeks gestation were enrolled into the prospective study. One-hour glucose screening test was performed before initiation of hydration treatment. Forty pregnant women with normal 1-hour glucose results, who also had responded to hydration therapy, made up our study group. Twenty-four hours, 72 hours, and 1 week after administration of betamethasone, 50-g glucose challenge tests were again performed. A 3-hour glucose tolerance test was performed in pregnant women, whose 1-hour screening test had been positive 1 week after corticosteroid administration. In the evaluation of data, one-way, variance analysis and Tukey's multiple comparison test were used. The mean value of 1-hour glucose results of 50-g challenge test at the 24 hours was significantly higher than the mean value of 1-hour glucose results of the test done initially before betamethasone administration and than those of the tests done at 72 hours and 1 week (p < 0.001 for these three groups). There was no statistically significant difference between the mean values of 1-hour glucose results of the test done before betamethasone administration and both the results of the tests done at 72 hours (p = 0.96) and 1 week (p = 0.99), separately. There was no significant difference between the mean 1-hour glucose results of the tests at 72 hours and 1 week (p = 0.99). The test results were positive in 42.5%, 10%, and 5% of the patients, respectively at 24 hours, 72 hours, and 1 week. The betamethasone administration significantly deteriorates 1-hour glucose screening test results in the nongestational diabetic patients but this effect of betamethasone is transient. Because of its high false-positivity at 24 hours (42.5%) and at 72 hours (10%) in women with initial negative 1-hour glucose screening test, we suggest that 1-hour glucose screening test in pregnant women be postponed at least 1 week after betamethasone administration or perform the test before administration of betamethasone.

KEYWORDS

Betamethasone treatment - 1-hour (50-g) glucose screen - 3-hour (100-g) glucose tolerance test

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