Starting the day’s first meal earlier may shift the body’s daily glucose rhythm and reduce overnight glucose levels in gestational diabetes, highlighting meal timing as a potential lifestyle factor worth exploring in pregnancy care.
Study: Early meal timing improves nocturnal glucose in pregnancies complicated by gestational diabetes. Image Credit: Natalia Deriabina / Shutterstock
In a recent study published in the journal Diabetologia, researchers examined whether the timing of the first daily meal was associated with differences in 24-hour glucose patterns in pregnancies complicated by gestational diabetes.
Could the timing of breakfast influence blood sugar during pregnancy?
Gestational diabetes affects roughly one in ten pregnancies in the United States and increases the risk of complications such as pre-eclampsia, high birthweight, and neonatal metabolic problems. Glycemic control in pregnancy is therefore very important for maternal and fetal health. Lifestyle interventions, particularly dietary modifications and exercise, remain the first-line strategies for controlling glucose levels.
Traditionally, nutritional advice has focused on carbohydrate quantity and type. However, emerging research suggests that when people eat may also influence metabolism because the body’s circadian rhythm regulates insulin release and glucose processing. Having meals earlier in the day can better align with natural metabolism. However, there are still limited studies in pregnant populations, underscoring the need for further research.
Researchers analyze glucose monitoring data to investigate meal timing
The researchers conducted a secondary analysis of data from a randomized controlled trial investigating glucose monitoring strategies in pregnant individuals diagnosed with gestational diabetes. The eligibility criteria included individuals diagnosed with gestational diabetes who were 20 to 35 weeks pregnant at the time of recruitment. Recruitment occurred between June 2021 and November 2023 at Oregon Health and Science University.
All participants were initially assigned to one of two groups: either real-time continuous glucose monitoring (CGM) or blinded CGM while continuing standard self-capillary blood glucose (SCBG) measurements.
For the present analysis, participants were included only if they recorded postprandial SCBG readings that could indicate meal timing. After excluding incomplete data, night-shift work, insufficient recordings, and outliers, 71 participants remained for analysis. Researchers estimated meal timing by assuming meals occurred approximately one hour before postprandial blood glucose measurements.
The median time of the first meal was used to classify participants into two groups. Those who had their first meal earlier than 09:56 hours were categorized as early eaters, while those who ate later were identified as late eaters. Continuous glucose monitoring data were analyzed in 5-minute intervals to construct 24-hour glucose profiles. Statistical models, including circadian rhythm analyses, evaluated daily, daytime, and evening glucose patterns while adjusting for maternal age, gestational age, medication use, and study group assignment.
Early and late eaters show distinct daily glucose rhythms
Of the 111 participants enrolled in the parent trial, 71 met the criteria for analysis after exclusions related to incomplete glucose records or irregular monitoring patterns. Participant characteristics were largely similar between the early-eating and late-eating groups for most baseline factors, such as age, race, gestational age at diagnosis, and baseline glucose measurements. However, the early-eating group had a higher prevalence of a first-degree family history of diabetes.
Both groups included individuals managing gestational diabetes through diet alone as well as those requiring medication.
Meal timing patterns varied across participants. In the early-eating group, the first meal typically occurred between 06:22 and 09:45 hours, whereas in the late-eating group, the first meal occurred between 09:56 and 14:32 hours. The final meal also differed slightly between groups, with early eaters finishing earlier in the evening compared with late eaters.
The early-eating group had a longer daily eating interval, averaging nearly 10 hours between the first and last meals, because their first meal occurred earlier in the day, while the final meal timing differed only modestly between groups.
Continuous glucose monitoring revealed clear daily rhythms in glucose levels. Across all participants, glucose concentrations tended to rise during the day and fall overnight, reflecting natural metabolic cycles. However, the timing of this rhythm differed between groups. Individuals who ate earlier showed a shift in their glucose rhythm toward earlier hours, meaning both peak and low glucose levels occurred earlier in the day.
Earlier meals linked to lower nighttime glucose levels
During daytime hours, glucose patterns differed primarily in timing rather than magnitude. The early-eating group showed a higher rise in glucose levels in the morning, reflecting earlier food intake. Despite these differences in timing, the overall average daytime glucose values did not differ significantly between groups.
Declining glucose levels were seen during the nighttime across both groups. However, late eaters had significantly higher glucose levels than early eaters during sleep. On average, late eaters had approximately 0.26 mmol/L higher nocturnal glucose values than early eaters. Late eaters had a more rapid decline in glucose during the night than early eaters, but they started with higher nocturnal glucose levels.
Other continuous glucose monitoring variables such as mean 24-hour glucose levels, time in range (TIR), glycemic variability, and mean amplitude of glycemic excursions (MAGE) were comparable across groups. Postprandial SCBG readings following the first and last meals also did not differ significantly.
Exploratory analyses further examined combinations of early and late meal timing for both the first and last meals. These analyses showed that individuals who both started and ended eating late in the day exhibited the highest nocturnal glucose levels compared with those who ate earlier overall.
Earlier eating may offer a simple strategy for gestational diabetes management
The findings suggest that meal timing may influence glucose regulation during pregnancy, particularly during nighttime hours. Individuals who began eating earlier in the day showed lower nocturnal glucose levels and an earlier daily glucose rhythm compared with those who ate later.
However, because this was a secondary observational analysis rather than a randomized meal-timing intervention, the findings demonstrate an association rather than proving that earlier eating directly improves glucose control.
The results also showed that most overall glucose metrics, including mean 24-hour glucose levels and time in range, were similar between groups, indicating that the primary difference related specifically to nocturnal glucose levels and the timing of the daily glucose rhythm.
Although nocturnal glucose levels are considered clinically important because previous studies have linked higher overnight glucose with adverse fetal outcomes, this study did not directly measure pregnancy or neonatal outcomes. Earlier meal timing could therefore represent a potential lifestyle strategy warranting further investigation to support gestational diabetes management.