Higher positive screen rate for gestational diabetes with fasting vs fed 1-hour glucose tolerance test

Question clinique

Do positive screen rates differ with fasting versus fed 1-hour glucose tolerance tests in second-trimester pregnancy?

L’Essentiel

The positive screen rate for the 1-hour 50-g oral glucose tolerance test was more than double among participants at greater than 24 weeks' gestation who had fasted for at least 6 hours compared with those who had eaten within 2 hours prior to testing. This study suggests, but doesn't prove, that prolonged fasting prior to 1-hour glucose tolerance testing leads to false positive results and unnecessary second-step testing. A larger study, powered to evaluate clinically meaningful differences in maternal and infant outcomes, is needed. 1b-

Plan de l'etude: Randomized controlled trial (nonblinded)

Financement: Self-funded or unfunded

Cadre: Outpatient (primary care)

Reviewer

Linda Speer, MD
Professor and Chair, Department of Family Medicine
University of Toledo
Toledo, OH


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Commentaires

Arup Kumar Dhara

Impact assessment

Excellent

Arup Kumar Dhara

Impact assessment

Excellent

Howard Kai-Hao To

conclusions drawn from article

"This study suggests, but doesn't prove, that prolonged fasting prior to 1-hour glucose tolerance testing leads to false positive results and unnecessary second-step testing"

I think that using the word "suggests" may be a bit too strong and potentially misleading. Yes, there were more positive results in the fasted group vs. the fed group (31 vs 13), and there were more false positives in the fasted vs. fed (19 vs. 8) with no differences in outcome.

However, the fasted group had more than double the cases of gestational diabetes than the fed group (12 vs. 5). Even though the number of cases of GDM was too small for this study to detect a significant difference (i.e. underpowered), the trend indicates that there was a difference in the groups' GDM rate (more than double) that was in line with the difference in the screen positive rate (also more than double). Useful additional information would be the number of false negatives (if any) for either group.

An alternative statement that captures more of the nuance demonstrated in the study: "This study shows a dramatic difference in screening outcomes based on whether patients have eaten or not before the 1-hour OGTT. This is a significant limitation in an otherwise very common pregnancy screening test. Unfortunately, this study did not have enough participants to draw conclusions on the rate of gestational diabetes among both groups. Therefore, it is impossible to draw a conclusion regarding how to advise patients on eating before the 1-hour OGTT." from https://www.practiceupdate.com/content/fasting-compared-with-fed-and-or…

Anonymous

Diabeti screening

Good to know

Anonymous

gestational diabetes

simple is best