[The effect of long-term treatment of arterial hypertension with Ca antagonists on the renin-angiotensin-aldosterone system in diabetics. Hyporeninemic hypoaldosteronism].

During long-term treatment of arterial hypertension with calcium antagonists of the dihydropyridine type activation of the sympathetic nervous system and subsequently also of the renin-angiotensin-aldosterone system persists, while the haemodynamic reaction to vasodilatation, manifested by an elevated pulse rate and minute volume from the initial stage of therapy, recedes. In type II diabetics the basal and stimulated response of the renin-angiotensin-aldosterone system is reduced. The administration of calcium antagonists of the dihydropyridine type does not stimulate significantly the renin-angiotensin-aldosterone system as the starting function of the sympathetic nervous system is impaired within the framework of vegetative neuropathy. In almost 20% NIDDM plasma renin activity and aldosterone do not respond to furosemide administration and the vertical posture. In others the response is found but takes place at reduced levels. Hyporeninaemic hypoaldosteronism is thus manifested not so much by a drop of plasma renin and aldosterone beneath the lower range of reference values as by a reduced response to stimulation. Functional hyporeninaemic hypoaldosteronism is another, frequent late complication of diabetes. In advanced forms a further block of the renin-angiotensin-aldosterone system by ACE inhibitors can then produce, even in the absence of diabetic nephropathy, in the stage of chronic renal failure dangerous hyperkaliaemia which may threaten the patient. Dynamic examination of the sympathetic nerve and the renin-angiotensin-aldosterone system makes it possible to predict this condition. In practice it is necessary in diabetics with arterial hypertension after starting with ACE inhibitors during the first days to monitor repeatedly plasma potassium and creatinine. ACE inhibitors and calcium antagonists are otherwise for diabetics drugs of first choice which can arrest the progression of nephropathy, effectively reduced the blood pressure without causing deterioration of insulin resistance and hyperlipoproteinaemia and lead even to regression of hypertrophy of the vascular wall and left ventricle.