Objective: To determine the relation between blood pressure and insulin resistance in children and the differences between fasting insulin and the insulin clamp in that relation.
Methods: Children were randomly selected after blood pressure screening of 12 043 fifth--eigth grade Minneapolis, Minnesota, students, with stratification by systolic blood pressure (SBP) percentile [half from the upper 25th percentile (high blood pressure) and half from the lower 75th percentile (low blood pressure)]. Euglycemic insulin clamps were performed with an insulin infusion rate of 1 mU/kg per min and a variable infusion of 20% glucose to maintain plasma glucose at 5.6 mmol/l (100 mg/dl). Insulin sensitivity (Mlbm) is defined as the amount of glucose required to maintain euglycemia (mg glucose infused/kg lean body mass (LBM)/min.
Results: Diastolic blood pressure was not significantly correlated with any of the body measurements or laboratory data. SBP was significantly correlated with virtually all measures of body size in males and females. SBP and Mlbm were not significantly correlated in either sex. The correlation between SBP and fasting insulin was significant for boys and girls, but became non-significant after adjustment for BMI. All measures of body fatness were significantly greater in the high blood pressure group, and a significant clustering effect for fasting insulin, BMI, triglycerides, and HDL-C was related to blood pressure. The clustering effect was similar when Mlbm was substituted for fasting insulin and was similar for boys, girls, blacks and whites.
Conclusions: These results suggest that level of blood pressure in children is mediated through body fat and that insulin resistance, as determined by the insulin clamp, does not play a primary role at this age of development. Nevertheless, the clustering effect of the risk factors according to SBP grouping is consistent with an early relation of blood pressure to the insulin resistance syndrome.