OBJECTIVE: To investigate the influence of prior food ingestion on the predictive value of a screening test for gestational diabetes mellitus.
METHODS: This prospective, nonrandomized study enrolled 1,387 pregnant women who underwent the 50-g glucose challenge test. Gestational diabetes mellitus was diagnosed according to the National Diabetes Data Group criteria. A nutritional survey of dietary information before the glucose challenge test was conducted. The patients were stratified into three groups based on the time of last food ingestion (fasting interval): 1 hour or less, 1–2 hours, and more than 2 hours. The more than 2-hours fasting interval group was defined as the “fasting” group, and the combined 1 hour or less and 1–2 hours fasting interval groups were defined as the “fed” group. We calculated the positivity rate and the positive predictive value to detect the predictive value.
RESULTS: Among women who fasted 1 hour or less, 1–2 hours, and more than 2 hours before a glucose challenge test, 2.5%, 3.1%, and 6.9% were diagnosed with gestational diabetes mellitus, respectively. The positive predictive value of the glucose challenge test was greater in the fasting group than in the fed group (27.1% compared with 13.7%, P=.003). A multinomial logistic analysis showed that gestational diabetes mellitus was more prevalent in the fasting group than in the fed group (adjusted odds ratio 2.86, 95% confidence interval 1.65–4.95).
CONCLUSION: Our findings suggest that food intake influences the predictive value of the gestational diabetes screening test.
LEVEL OF EVIDENCE: II