Effect Modification Investigation Using SAS ® - A Model Building Exercise

The positive association of adiposity with insulin and negative association with adiponectin have been documented along with evidence that adiponectin and insulin are inversely associated. The purpose of this study was to determine the influence of adiponectin on insulin and its potential to modify the relationship between insulin and percent body fat (%BF) in 441 black and white 14-19 y olds. An exercise in model building will be presented showing the progression from a model of the insulin and %BF relationship to the addition of the modification variable of adiponectin. Statistical graphics will be used to help understand the nature of the relationships among the variables. Results show a significant %BF*adiponectin interaction such that the positive relationship between %BF and insulin was attenuated in those with higher %BF and higher adiponectin. These findings suggest that higher adiponectin levels may be protective to individuals with high %BF by increasing glucose tolerance.