OBJECTIVE: The study was conducted in 12 middle schools to determine the prevalence of diabetes, pre-diabetes, and diabetes risk factors in eighth-grade students who were predominantly minority and evaluate the feasibility of collecting physical and laboratory data in schools. RESEARCH DESIGN AND METHODS: Anthropometric measurements and fasting and 2-h post-glucose load blood draws were obtained from approximately 1,740 eighth-grade students. RESULTS: Mean recruitment rate was 50% per school, 49% had BMI > or = 85th percentile, 40.5% had fasting glucose > or = 100 mg/dl, 0.4% had fasting glucose > or = 126 mg/dl, and 2.0% had 2-h glucose > or = 140 mg/dl and 0.1% > or = 200 mg/dl. Mean fasting insulin value was 30.1 microU/ml, 36.2% had fasting insulin > or = 30 microU/ml, and 2-h mean insulin was 102.1 microU/ml. Fasting and 2-h glucose and insulin values increased across BMI percentiles, and fasting glucose was highest in Hispanic and Native American students. CONCLUSIONS: There was a high prevalence of risk factors for diabetes, including impaired fasting glucose (> or =100 mg/dl), hyperinsulinism suggestive of insulin resistance (fasting insulin > or = 30 microU/ml), and BMI > or = 85th percentile. These data suggest that middle schools are appropriate targets for population-based efforts to decrease overweight and diabetes risk.