Impact of personalized diet plans guided by gut microbiota profiles on metabolic health outcomes in adults with prediabetes: A randomized controlled trial

Project Abstract

This randomized controlled trial investigates whether personalized diet plans tailored to individual gut microbiota profiles can improve metabolic health outcomes in adults with prediabetes compared to standard dietary advice. A total of 240 adults aged 30–65 with impaired fasting glucose or HbA1c 5.7–6.4% were recruited from urban primary care clinics and stratified by sex, BMI, and baseline HbA1c before randomization to either the microbiota-guided diet group (n=120) or the control group receiving conventional dietary guidance (n=120) for 12 months. Baseline assessments included anthropometrics, fasting plasma glucose, HbA1c, lipid panel, inflammatory markers (CRP, IL-6), insulin resistance (HOMA-IR), blood pressure, body composition via DXA, dietary intake using 7-day recalls, physical activity, and stool samples for 16S rRNA sequencing to establish microbiota composition and predicted metagenomic functions. The microbiota-guided diet was personalized using an algorithm integrating microbial enterotypes, relative abundances of short-chain fatty acid-producing taxa, bile acid metabolizers, and microbial gene pathways linked to host glycemic control, modulating macronutrient distribution, fiber type and amount, prebiotic and probiotic components, and meal timing to optimize microbial metabolites such as butyrate, propionate, and secondary bile acids. Primary outcomes were changes in HbA1c and HOMA-IR at 12 months. Secondary outcomes included fasting plasma glucose, OGTT 2-hour glucose, lipid profile, blood pressure, body weight and composition, inflammatory and oxidative stress markers, hepatic steatosis by ultrasound-based scores, gut permeability markers, and adherence metrics. Adherence was monitored via self-reported dietary diaries, digital nutrition tracking, and periodic stool-based microbiota re-analysis to observe diet-induced microbial shifts. The trial employed a pragmatic design with monthly dietitian visits, quarterly coaching calls, and a digital platform for real-time feedback and reminders. Statistical analysis used mixed-effects models to account for repeated measures and potential clustering by site, adjusting for baseline values, age, sex, BMI, and physical activity. Intention-to-treat and per-protocol analyses were conducted, with sensitivity analyses addressing missing data via multiple imputation and examining effect modification by baseline microbial diversity and BMI category. Interim analyses evaluated safety and early efficacy signals, with predefined stopping rules for adverse events or futility. We hypothesize that the microbiota-guided diet will yield greater reductions in HbA1c and HOMA-IR than standard dietary advice, mediated by enhanced production of beneficial microbial metabolites, improved gut barrier integrity, and favorable inflammatory profiles. Exploratory analyses will assess correlations between specific taxa shifts (e.g., increased SCFA producers), predicted microbial pathways (amino acid and carbohydrate metabolism), and glycemic outcomes, as well as potential interactions with sex and BMI. If successful, findings could establish a scalable, microbiota-informed dietary intervention framework for delaying progression to type 2 diabetes in prediabetic adults and inform precision nutrition strategies that leverage host–microbiome ecology to optimize metabolic health.

Project Overview

What This Project Is About

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A plain-language overview of the topic and what the project investigates.

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The Problem It Addresses

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What problem or gap this project tackles and why it matters to the field or society.

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Objectives of the Project

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1. Describe how gut bacteria profiles influence diet responses in prediabetes.
2. Test whether personalized diet plans improve metabolic health markers compared with standard advice.
3. Explain the role of gut microbiota in obesity,?? control, and inflammation in adults with prediabetes.

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What You Will Do Step by Step

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1. Review basic literature on gut microbiota, nutrition, and prediabetes.
2. Recruit adult participants with prediabetes and collect baseline health data.
3. Analyze stool samples to profile gut microbiota and group participants accordingly.
4. Develop personalized diet plans based on microbiota profiles.
5. Implement dietary interventions for a defined period and monitor adherence.
6. Measure metabolic health outcomes (e.g., fasting glucose, HbA1c, lipids) before and after the intervention.
7. Compare results with a control group receiving standard dietary guidance.
8. Use simple statistics to assess differences and summarize findings.

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Expected Outcome

Better metabolic health indicators in the personalized diet group, with insights into how gut microbiota may mediate response to diet.