This Cochrane review summarizes evidence from eight randomized controlled trials that examined the effects of exercise alone or exercise combined with diet interventions on preventing type 2 diabetes in high-risk groups. The trials involved over 4,000 participants and lasted from one to six years. The review found that interventions combining exercise and diet reduced the relative risk of developing diabetes by 37% compared to standard recommendations. These interventions also had beneficial effects on weight, waist circumference, and blood pressure. However, more evidence is needed on the effects of exercise alone and on outcomes like diabetes-related morbidity, mortality, and quality of life.