Angiotensin II receptor blockers are used primarily for the treatment of hypertension where the patient is intolerant of ACE inhibitor therapy primarily because of persistent and/or dry cough. They do not inhibit the breakdown of bradykinin or other kinins, and are thus only rarely associated with the persistent dry cough and/or angioedema that limit ACE inhibitor therapy. More recently, they have been used for the treatment of heart failure in patients intolerant of ACE inhibitor therapy, in particular candesartan. Irbesartan and losartan have trial data showing benefit in hypertensive patients with type 2 diabetes, and may delay the progression of diabetic nephropathy. A 1998 double-blind study found "that lisinopril improved insulin sensitivity whereas losartan did not affect it." Candesartan is used experimentally in preventive treatment of migraine. Lisinopril has been found less often effective than candesartan at preventing migraine.