The primary objective of this research project is to define the relation of insulin resistance to blood pressure in children and to change in blood pressure that occur during adolescence. If insulin resistance is related etiologically to hypertension, it should predate the appearance of elevated blood pressure or it should increase coincident with a rise in blood pressure in individuals tracking toward hypertensive blood pressure levels. The specific aims for this proposal are: 1) to conduct blood pressure screening of 11,500 5-8 grade (11-15 yr. old) Minneapolis school children to develop a blood pressure distribution for recruitment of an enriched study population of 50% from the upper 15% of the distribution and 50% randomly selected from the remaining 85% of the distribution; 2) to obtain baseline measurements of blood pressure; anthropometric measurements, fasting serum insulin, glucose and lipids; measure of insulin resistance; forearm vascular resistance; and echocardiography in 11-15 yr. old individuals; 3) to repeat these measurements when the participants are 13-17 yr. old. These data will be used to address the hypotheses that 1) in early adolescence and prior to the onset of hypertension, insulin resistance is positively associated with systolic and diastolic blood pressure, forearm vascular resistance, left ventricular wall thickness, and plasma lipids; 2) during adolescence insulin resistance at baseline and/or changes in insulin resistance will predict changes in systolic and diastolic blood pressure and will be associated with changes in skinfold thickness, body mass index, waist-hip ratio and lipids; 3) changes in insulin resistance will be correlated with changes in forearm vascular resistance such that either an increase in insulin resistance predates changes in the peripheral vasculature and insulin resistance at baseline will predict changes in forearm vascular resistance or changes in the peripheral vasculature predate an increase in insulin resistance, and forearm vascular resistance at baseline will predict degree of insulin resistance; 4) changes in insulin resistance during adolescence will be associated with changes in left ventricular size. Dr. Michael Jensen is facilitating obesity-related studies from investigators at the University of MN as part of the MN Obesity Center. Dr. Alan R. Sinaiko, Department of Pediatrics at the University of MN, is studying the role of obesity and hypertension in children. The only practical measure of body composition that he can make is total body water. His ability to estimate body composition from total body water will greatly improve his ability to interpret the effects of body composition on the development of hypertension in African-American and Caucasian adolescents. The Biomedical Mass Spectrometry Core is analyzing Dr. Sinaiko's samples for enrichment of 18O and 2H in water. Up to 400 determinations are expected. No ancillary support is provided.