Plasma glucose and insulin levels were determined in a total biracial community of 3313 children, ages 5-17 years. Black children have significantly higher insulin and lower glucose levels than white children of comparable age and sex. Children of diabetic parents have elevated levels of age- and weight-adjusted fasting cholesterol. Moderate tracking (r = 0.31) of glucose levels over a 3-year period was seen. Insulin levels, however, track well (r = 0.36) only in older children (ages 9-14 years at initial examination). Fasting insulin levels are positively related to measures of obesity, systolic and diastolic blood pressure, triglyceride, beta-lipoprotein cholesterol and pre-beta-lipoprotein cholesterol levels. In addition, insulin levels are negatively related to alpha-lipoprotein cholesterol levels. Fasting glucose levels are positively related to systolic and diastolic blood pressure, triglycerides, pre-beta-lipoprotein cholesterol, and obesity levels. The relationship of plasma glucose and insulin levels to the traditional cardiovascular risk factors in children emphasizes the importance of subtle abnormalities in carbohydrate metabolism in the early natural history of cardiovascular disease.