Food Order Shapes Gut Microbiota in Gestational Diabetes Mellitus: A Metagenomic Study

Ria Murugesan^1*Janardanan Subramonia Kumar^1*Kakithakara Vajravelu Leela¹Sachdev Meenakshi²Shubhashree Thiruselvam¹Abhishek Satheesan¹

• ¹SRM Medical College Hospital and Research Centre, Chengalpattu, India
• ²Tamil Nadu Government Multi Super Specality Hospital, Chennai, India

Background: The order of macronutrient intake can influence metabolic outcomes. In gestational diabetes mellitus (GDM), where dietary control is critical, the gut microbiota may play a mediating role. However, the effect of food sequencing on the gut microbiome and glycemic control in GDM remains underexplored. Objective: To assess the impact of a structured food order-based dietary intervention on gut microbiota composition and glycemic control in women with GDM. Methods: In this randomized, open-label trial, forty pregnant women with GDM were assigned to either a Food Order (FO) group (n = 20), instructed to consume meals in the sequence of fiber, protein, and carbohydrates, or a No-order (NO) control group (n = 20), who followed their usual diet. The intervention lasted 12 weeks, during which stool samples were collected pre-and post-intervention for metagenomic sequencing using Oxford Nanopore Technology (ONT). Fasting and postprandial blood sugar (FBS, PPBS) levels were monitored every two weeks. A mobile health (JotForm) app was used to track meal adherence, and structured pre-and post-intervention questionnaires were administered to assess awareness, satiety, and behavioural changes. Results: The FO group showed significant reductions in FBS and PPBS (p < 0.001), increased microbial diversity (Shannon index), higher levels of Akkermansia and Bifidobacterium, and a reduced Firmicutes/ Bacteroidota (F/B) ratio. Questionnaire responses reflected improved satiety, reduced hunger cravings, and willingness to continue the food sequence approach. Conclusion: Food sequencing may have contributed to significant improvements in glycemic control, positively influenced gut microbiota, and enhanced dietary behaviour in women with GDM. This approach may offer a simple, non-pharmacological strategy for managing GDM during pregnancy. Clinical Trial Registration: Study was registered in Clinical Trial Registry of India, identifier CTRI/2024/01/061220 https://ctri.nic.in/Clinicaltrials/regtrial.php?modid=1&compid=19&EncHid=81473.12293.