Renin-angiotensin-aldosterone system in diabetes mellitus.

The renin-angiotensin-aldosterone system appears to function normally in uncomplicated diabetes mellitus. Alterations in this system, however, have been observed in several of the microvascular and electrolyte complications associated with this disease. Plasma renin activity (PRA) and aldosterone are decreased in diabetic with nephropathy and hypertension, in those with neuropathy including orthostatic hypotension, and in those with hypoaldosteronism. PRA is low in rats with uncontrolled, nonketotic diabetes, and pressor responsiveness to angiotension II is increased in patients with diabetic retinopathy. Potential mechanisms responsible for the decreased PRA include plasma volume expansion, hyalin destruction of the juxtaglomerular cells, defective synthesis of renin, and inadequate catecholamine stimulation of renin, and inadequant cathecholamine stimulation of renin release. In diabetic ketoacidosis, PRA and aldosterone are stimulated secondary to the associated dehydration with hypovolemia. This report reviews the current status of the function of the renin-angiotensin-aldosterone system in diabetes mellitus and proposes a possible role for the altered function of this system in the pathophysiology of several diabetic complications.