Abstract Disclosure: C.A. Fermin-Martinez: None. O.Y. Bello-Chavolla: None. N.E. Antonio-Villa: None. D. Ramirez Garcia: None. J.A. Seiglie: None. Background: Prediabetes has been consistently linked to high risk of diabetes progression, cardiovascular disease, and all-cause mortality. However, no large-scale studies have been conducted in Mexico or Latin America examining these associations despite the growing prevalence of this condition in low- and middle-income countries. Methods: We analyzed data from 117,227 adults without diabetes aged ≥35 years who participated in the Mexico City Prospective Study (1998-2004). Individuals with self-reported chronic comorbidities at baseline were excluded to mitigate reverse causation. Participants were followed-up until January 1st, 2021 for cause-specific mortality. We defined prediabetes according to the American Diabetes Association (ADA, HbA1c ≥5.7%) and the International Expert Committee (IEC, HbA1c ≥6.0%) definitions. Cox regressions were used to estimate prediabetes-related risk for all-cause and cause-specific mortality, stratified by sex and age-at-risk and adjusted for municipality of residence, education level, physical activity, smoking, alcohol consumption, and adiposity markers. Results: Compared to individuals with normoglycemia, participants with IEC-defined prediabetes had a higher risk of all-cause (HR 1.16, 95%CI 1.05-1.27), cardiac (HR 1.29, 95%CI 1.05-1.59), renal (HR 1.59, 95%CI 1.14-2.23), and acute diabetes-related (HR 2.60, 95%CI 1.52-4.43) mortality at ages 40-74 years compared to normoglycemic participants. HRs were attenuated at older ages. Results were broadly similar irrespective of the definition of prediabetes except for cardiac deaths, in which the risk was non-significant using the ADA cutoff (HR 1.14, 95%CI 0.99-1.31). Long-term effects of prediabetes (IEC-defined) accounted for ∼37% of renal deaths and ∼61% of acute diabetes-related deaths in Mexican adults without diabetes at baseline. Conclusion: Prediabetes is an important risk factor that accounts for a significant fraction of all-cause, cardiac, renal, and acute diabetes-related deaths among Mexican adults, particularly when using the higher threshold of IEC-defined prediabetes. Endpoint-driven definitions of prediabetes should be considered for widespread implementation of screening and preventive strategies that minimize overdiagnosis and improve cardiometabolic outcomes in this population. Presentation: 6/1/2024