TXNIP and Hyperglycemia: Three different markers of HG stress were then measured (Fig. 2): (1) the ROS; (2) the subunits Nox4 and P22−phox of the enzyme NAD(P)H Oxidase, shown to be a source of ROS in the endothelium of diabetic patients [15]; and (3) the thioredoxin interacting protein (Txnip), which has been demonstrated to be increased under hyperglycemia and ROS overproduction [16, 17].