Poster Presentation Australian and New Zealand Obesity Society Annual Scientific Conference 2024

An exploration of how dietary intake, according to time of day, influences glucose homeostasis in pregnant women with and without gestational diabetes: a systematic review (#249)

Kai Liu 1 2 3 , Jessica A Grieger 1 2 3 , Zoe E Davidson 4 , Amy T Hutchison 1 2 3 , Maxine P Bonham 4
  1. Adelaide Medical School, University of Adelaide, Adelaide, South Australia, Australia
  2. Robinson Research Institute, The University of Adelaide, Adelaide, SA, Australia
  3. Lifelong Health Theme, South Australian Health and Medical Research Institute, Adelaide, South Australia, Australia
  4. Department of Nutrition, Dietetics and Food, Monash University, Melbourne, Victoria, Australia

Background Dietary management for gestational diabetes mellitus (GDM) is primarily through equal distribution of carbohydrates across the day to avoid hyperglycaemic episodes. Such management does not account for the influence of meal timing and circadian variation on postprandial glucose levels.

Objective This systematic review explored the effect of meal timing and macronutrient manipulation on postprandial glucose homeostasis in pregnant women with or without GDM.

Methods Four databases were systematically searched in August 2023 for randomised controlled trials (RCT) and non-RCTs. Inclusion was singleton pregnancies, reporting a minimum two eating occasions (e.g. morning and afternoon/evening) with the associated postprandial glucose responses of ≥2 hours. Pregnant women requiring insulin were excluded. Postprandial glucose response and macronutrient composition of each meal were extracted for descriptive analysis.

Results Nineteen studies met the inclusion criteria with 14 reporting data that met the aim. Irrespective of GDM status, pregnant women had higher postprandial glucose levels in the afternoon/evening than in the morning. Compared with healthy pregnant women, women with overweight or obesity, or those with GDM, showed a higher 2-hour postprandial glucose response after dinner. Five RCTs compared a control diet with an intervention diet that manipulated carbohydrate content through reducing overall glycaemic load or increasing dietary fibre. Four of these reported lower 24-hour mean glucose or reduced postprandial insulin secretion in the intervention versus control diets. One RCT examined high versus low morning carbohydrate intake but did not report postprandial glucose variation across the day. There is limited evidence on how macronutrient modification can affect postprandial glucose at night.

Conclusion In pregnancy, poorer postprandial glucose tolerance was observed at night versus the morning, especially among women with GDM, or with overweight or obesity. Reducing glycaemic load may improve overall glycaemic control but whether timed carbohydrate intake can improve postprandial glucose tolerance in pregnancy remains unclear.