<qa>  What is the effect of walnut-included diet on endothelial function?- To assess the effects of a walnut-included diet with or without caloric intake adjustment for a 6-month period on endothelial function, lipid panel levels, fasting glucose level, fasting insulin level and anthropometric measures in adults at risk for diabetes. Specifically, to show clinically meaningful improvement in endothelial function, lipid panel, fasting blood glucose, hemoglobin A1c HbA1c, anthropometric measures and endothelial function with inclusion of walnuts in the diet in adults at risk for diabetes. 