ACE inhibition is widely used for treatment of arterial hypertension or congestive heart failure. No change occurs in glucose metabolism either in diabetic or non diabetic subjects. No change occurs in glucose metabolism in patients with chronic renal failure. Glucose intolerance induced by diuretics is attenuated when ACE inhibitor is associated with thiazides. In some very rare circumstances (with high plasmatic levels of norepinephrine), insulin sensitivity seems to be enhanced by captopril. Then, in clinical use, no adverse effect occurs with ACE inhibition in non diabetic or diabetic subjects. Under thiazide treatment, ACE inhibitors protect against glucose intolerance.