HH was defined as subnormal free testosterone concentration (2). AMPKα is important in mediating the action of exercise and in enhancing glucose transport. This mechanism, although independent of insulin action, can amplify insulin signal transduction, since insulin action also involves AKT kinase and GLUT4. These effects may contribute to the improved insulin sensitivity following testosterone therapy. Testosterone modulates the expression of AMPKα and phosphorylated AMPKα.