The impact of plant-based diets on the prevention and treatment of type 2 diabetes

Type 2 diabetes (T2D) affects more than 500 million people worldwide. Dietary modification and weight management remain central to diabetes prevention and management. Plant-based diets (PBDs), particularly whole-food, fully plant-based diets (FPBDs), are associated with lower risk of developing T2D and improved clinical outcomes for those with T2D. This narrative review summarizes evidence from major cohort studies, randomized clinical trials and national dietary guidelines evaluating the role of PBDs, particularly whole-food, FPBDs, in the prevention and treatment of T2D. PubMed and Google Scholar were searched, from 2024 to 2026, using search terms such as “plant-based diet,” “whole-food plant-based diet,” “vegan diet,” “type 2 diabetes,” “insulin resistance” and “diabetes prevention.” Studies involving human participants, including randomized controlled trials and prospective cohort studies, as well as systematic reviews, meta-analysis, mechanistic studies and relevant national dietary guidelines, were considered. Greater adherence to PBDs, which emphasize the consumption of high-fibre plant foods, are associated with a significantly lower risk of developing T2D, improved glycemic control and reductions in diabetes medication requirements in established diabetes. Clinical trials of low-fat vegan diets report reductions in hemoglobin A1c of up to 1.2 percentage points and average weight losses exceeding 6 kg compared with conventional dietary approaches. Taken together, available evidence suggests that whole-food, plant-based diets are a safe and practical option for the prevention and management of T2D, though evidence strength varies across outcomes. Further long-term randomized studies are needed. Even gradual shifts toward plant-predominant dietary patterns may offer metabolic benefits, making this a practical option for those unable or unwilling to adopt a fully plant-based diet. Clinicians should routinely discuss and support the adoption of PBDs as an evidence-based lifestyle intervention for patients at risk for or living with T2D.