Food-Specific Morning and Night Intake Scores Are Associated with Impaired Glucose Tolerance during Pregnancy

Background: Impaired glucose tolerance (IGT) during pregnancy is associated with numerous short- and long-term adverse health outcomes. Diet is a key factor influencing glucose tolerance, yet there are little data on the relationship between specific foods or intake timing and IGT. Objectives: We examined whether food category intakes and their timing are associated with IGT. Methods: We used data from the temporal research in eating, nutrition, and diet during pregnancy study, which recruited 144 pregnant persons at gestational age <18 wk. Participants provided ≤28 d of food records (before and after photos for each eating occasion and text notes), and access to their electronic health records (EHR). We introduced morning and night intake scores (weighted measures reflecting the proportion of intakes consumed during nocturnal or morning periods) that incorporate exact intake timing rather than using a single threshold. We used logistic regression to estimate associations [odds ratio (OR) and 95% confidence intervals (CI)] between temporal intake features and IGT (determined from EHR laboratory results), controlling for diet quality, age, total daily energy intake, physical activity, and prepregnancy body mass index, and conducted sensitivity analysis. Results: We found a significant positive association between mean daily red meat intake and IGT (OR = 3.68, 95% CI: 1.68, 8.75), and a negative association with IGT for night egg intake (OR = 0.95, 95% CI: 0.93, 0.98). These associations remained after sensitivity analysis. Associations between macronutrient and energy intake and IGT were not statistically significant. Conclusions: Our novel approach to modeling intake timing uncovered a new negative association between night egg intake and IGT, and a positive association between red meat intake and IGT. Macronutrient and energy intake were not significant predictors of IGT, showing the importance of capturing specific food intake and timing. Future research is needed to determine if these observed associations are causally linked to IGT.