Introduction and Objective: This study aims to determine the minimum weight loss required for diabetes prevention in the Korean population. Methods: The Korean Diabetes Prevention Study (KDPS), a prospective, multicenter, randomized controlled trial, enrolled prediabetic adults aged 30-70 with a body mass index ≥23 kg/m2 from 2016 to 2022. Participants were assigned to standard management, lifestyle modification, or metformin groups. The primary outcome was the cumulative incidence of diabetes. A survival tree model identified the optimal weight loss threshold, and diabetes incidence was analyzed using Kaplan-Meier curves and Cox regression. Results: Among 701 participants who completed the 6-month intervention, a minimum weight loss threshold of 1.6% was identified for diabetes prevention. Participants achieving ≥1.6% weight loss had significantly higher diabetes-free probabilities over 72 months than those with <1.6% weight loss (p <0.002). After adjusting for sex, age, and metabolic factors, the ≥1.6% weight loss group had a 37-40% lower risk of diabetes, with adjusted hazard ratios of 0.63 (95% confidence interval [CI]: 0.48-0.82; p <0.001) and 0.60 (0.45-0.80; p <0.001). Conclusion: Achieving ≥1.6% weight loss reduces diabetes risk in overweight, prediabetic individuals, supporting the revision of Korea’s diabetes prevention guidelines based on KDPS evidence. Disclosure H. Sang: None. S. Shin: None. J. Choi: None. Y. Yoon: None. S. Chon: None. J. Woo: None.