The Role of Diet and Physical Activity in Gut Microbiota Modulation in Type 2 Diabetes Management: A Systematic Review of Clinical Trials

CONTEXT: Lifestyle interventions focused on dietary and physical activity strategies are the cornerstone of type 2 diabetes (T2D) prevention and management. While their clinical benefits are well established, less is known about their effects on reversing gut dysbiosis. OBJECTIVE: To investigate the role of gut microbiota modulation on T2D prevention or control in response to dietary and physical activity patterns in adults. DATA SOURCES: Medline (PubMed), Scopus, and LILACS databases were searched from inception to September 2024 to identify studies evaluating whether gut microbiota modulation could explain the clinical benefits of dietary and/or physical activity interventions in adults with T2D or prediabetes. DATA EXTRACTION: A literature search (May-September 2024) based on PICOS (Participants, Intervention, Comparison, Outcomes, Study design) criteria selected randomized controlled and quasi-experimental trials. Methodological quality was assessed using Joanna Briggs Institute tools, and the certainty of evidence was assessed using the GRADE (Grading of Recommendations Assessment, Development, and Evaluation) approach. DATA ANALYSIS: Of 2928 records identified, 11 moderate-quality clinical trials (n = 319 participants) were included, 6 of which were randomized controlled trials. All studies involved dietary interventions, and 3 also incorporated physical activity. Despite methodological heterogeneity, most reported beneficial effects of healthy diets, with or without physical activity, on T2D prevention and control through gut microbiota modulation. These interventions increased the abundance of health-associated genera (eg, Faecalibacterium, Akkermansia), improved microbial diversity, and reduced the Bacillota/Bacteroidota ratio. Functional pathway analyses showed positive shifts in amino acid and lipid metabolism, supported by metabolomic data linking microbial metabolites to improved metabolic outcomes. These microbial changes correlated with better glycemic control and lower inflammation, although some effects appeared transient and diet-dependent. CONCLUSION: Gut microbiota modulation plays a central role in the beneficial effects of lifestyle interventions on T2D prevention and management, particularly through increased abundance of short-chain fatty acid-producing bacteria associated with improved glucose metabolism, insulin sensitivity, and inflammatory profiles. SYSTEMATIC REVIEW REGISTRATION: PROSPERO registration no. CRD42024544408.