Antihypertensive drugs have disparate effects on blood glucose regulation. This bench-to-bedside review in Mayo Clinic Proceedings covers physiologic mechanisms and clinical studies which show that thiazide diuretics and beta blockers increase the risk for diabetes while angiotensin converting enzyme inhibitors and angiotensin receptor blockers have the opposite effect.
Despite their diabetogenic effects thiazide diuretics improved cardiovascular outcomes in ALLHAT. However, the duration of follow up in ALLHAT may have been too short to detect adverse consequences of diabetes.
Background: additional commentary and links from DB here and here.