PURPOSE: Little is known about the prevalence of prediabetes and associated risk of cardiovascular events and chronic kidney disease (CKD) with this reversable condition in survivors. METHODS: Prevalence of prediabetes (fasting plasma glucose 100-125 mg/dL or hemoglobin A1c 5.7%-6.4%) and diabetes was clinically assessed in 3,529 adults ≥5 years from childhood cancer diagnosis and 448 controls stratified by age. Cox proportional hazards regression estimated progression from prediabetes to diabetes, and risk of future cardiac events, stroke, CKD, and death. RESULTS: Among survivors, median age 30 years (IQR, 18-65), and the prevalence of prediabetes was 29.2% (95% CI, 27.7 to 30.7) versus 18.1% (14.5 to 21.6) in controls and of diabetes was 6.5% (5.7 to 7.3) versus 4.7% (2.7 to 6.6). By age 40-49 years, more than half of the survivors had prediabetes (45.5%) or diabetes (14.0%). Among 695 survivors with prediabetes and longitudinal follow-up, 68 (10%; median follow-up, 5.1 years) progressed to diabetes. After adjustment for demographic factors and body composition, risk of progression was associated with radiation exposure to the pancreatic tail ≥10 Gy (hazard ratio [HR], 2.7 [95% CI, 1.1 to 6.8]) and total-body irradiation (4.4 [1.5 to 13.1]). Compared with survivors with normal glucose control, adjusting for relevant treatment exposures, those with prediabetes were at increased risk of future myocardial infarction (HR, 2.4 [95% CI, 1.2 to 4.8]) and CKD (2.9 [1.04 to 8.15]), while those with diabetes were also at increased risk of future cardiomyopathy (3.8 [1.4 to 10.5]) or stroke (3.4 [1.3 to 8.9]). CONCLUSION: Prediabetes is highly prevalent in adult survivors of childhood cancer and independently associated with an increased risk of future cardiovascular and kidney complications. Prediabetes, a modifiable risk factor among childhood cancer survivors, represents a new target for intervention that may prevent subsequent morbidity and mortality.