Early meal timing improves nocturnal glucose in pregnancies complicated by gestational diabetes

Gestational diabetes (GDM) results in adverse outcomes for the pregnant individual and neonate. Lifestyle modifications are first-line interventions used to achieve pregnancy-specific glucose targets. We investigated how temporal eating patterns influence glucose concentrations in individuals with GDM. We hypothesise that eating the first meal early in the morning may lower overall 24 h interstitial glucose, which could be an intervention to improve 24 h glucose metrics among people with GDM.

This is a secondary analysis of pregnant people with GDM randomised to self-capillary blood glucose (SCBG) with or without additional real-time continuous glucose monitoring (CGM) for management of GDM. Participants measured SCBG and were included in the analysis if postprandial SCBG were available to infer meal timing (n=71). The cohort was split by the median time of first meal into early (first meal before 09:56 hours) and late eating (first meal after 09:56 hours) groups. The 24 h CGM glucose profiles were compared between groups by cosinor and linear analyses, adjusted for maternal and gestational age, medication usage, and primary study group assignment.

Over 24 h, glucose increased during the day and decreased during the night. This rhythm was shifted earlier for the early eating group (time-of-day: 24 h component: -0.32 mmol l^-1 min^-1, t_102,232=-188.9, p<0.001; 12 h component: -0.11 mmol l^-1 min^-1, t_102,232=-65.2, p<0.001; and group × time-of-day: 24 h component: 0.09 mmol l^-1 min^-1, t_102,232=37.9, p<0.001; 12 h component: 0.04 mmol l^-1 min^-1, t_102,232=15.3, p<0.001). During the daytime, there was a significant time-of-day (7.0 × 10^-4 mmol l^-1 min^-1, t_72,418=150.8, p<0.001) and group × time-of-day effect (7.0 × 10^-5 mmol l^-1 min^-1, t_72,418=10.0, p<0.001), but no group effect (0.01 mmol/l, t₆₅=0.06, p=0.950). Overnight, glucose decreased in both groups by approximately 0.67 ± 0.39 mmol/l. The late eating group, however, had significantly higher nocturnal glucose compared with the early eating group (group: 0.26 mmol/l, t₆₅=2.3, p=0.023, time-of-day: -0.09 mmol l^-1 min^-1, t_29,818=-119.0, p<0.001; and group × time-of-day effect: -0.01 mmol l^-1 min^-1, t_29,818=-11.8, p<001).

These results suggest that meal timing, with an emphasis on earlier eating patterns, is a potential lifestyle intervention that can improve nocturnal interstitial glucose.