Introduction and objective:
Type 2 diabetes mellitus affects more than 500 million adults worldwide and continues to increase. Diet shapes molecular pathways regulating insulin sensitivity, inflammation and glucose metabolism. Nutrigenomics studies nutrient-gene interactions, while epigenetics focuses on reversible mechanisms, such as DNA methylation, histone modifications and non-coding RNAs. This review synthesises evidence from 2017–2025 on how these processes support T2DM prevention.

Review methods:
A targeted narrative search of PubMed and PubMed Central was conducted to identify recent human evidence published between 2017–2025 on nutrigenomics, epigenetics, diet and T2DM prevention. Peer-reviewed clinical, cohort, mechanistic and review studies were prioritised and synthesised thematically.

Brief description of the state of knowledge:
Genetic variants, such as TCF7L2, FTO and PPARG, show modest, inconsistent diet-gene effects. Diet-induced changes in DNA methylation and histone marks influence insulin signalling, lipid metabolism and inflammatory pathways, but mostly associative and short-term. Mediterranean and plant-based diets align with more favourable molecular profiles, while high-fat, high-GI diets show adverse signatures. Early personalised-nutrition trials using genomic, metabolomic or microbiome data improve postprandial glucose responses in some individuals, but often fail to outperform standard dietary recommendations in broader populations.

Summary:
Nutrigenomic and epigenetic research improves understanding of how diet shapes metabolic risk, although clinical applicability remains limited. Most effects are small, variable across populations, and not consistently reproduced. Long-term, multi-ethnic and multi-omics studies are needed to validate biomarkers and determine whether they add predictive or therapeutic value beyond established dietary strategies.