The ACE I/D variant is also thought to affect a patient’s response to therapeutics commonly used in diabetes: angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs) are used to treat hypertension and numerous diabetic complications including retinopathy, nephropathy, neuropathy, CAN, and cardiovascular disease (175–181). This evidence concerns the gene ACE and Crouzon syndrome-acanthosis nigricans syndrome.