Comparison of nifedipine and clonidine for improvement of nightly blood pressure control in hypertensive type 2 diabetic patients with diabetic nephropathy and inverse circadian rhythm of blood pressure (non-dipping).

The influence of an additional administration of clonidine and of nifedipine at the evening on the nocturnal decrease of blood pressure was compared in a randomized cross-over study in 10 type 2-diabetic patients with nephropathy and inverse circadian rhythm (non-dipping despite antihypertensive treatment). After a 4-week lasting period of therapy the mean nocturnal blood presssure was lowered by clonidine from plus 4 +/- 4% to minus 7 +/- 6% and by nifedipine to minus 13 +/- 7%. This decrease of blood pressure at night was highly significant in both groups of therapy (p < 0.001) but nifedipine was more effective than clonidine in lowering the nocturnal blood pressure (p < 0.05). Nevertheless the inverse circadian rhythm could not be normalized in all patients. A significant decrease of blood pressure at night (> 10% decrease) was achieved in four of the patients with clonidine and in six of them with nifedipine therapy. Therefore in patients with severe hypertension and inverse circadian rhythm due to diabetic nephropathy the additional administration of nifedipine leads to a more significant decrease of the nocturnal blood pressure than clonidine, but normalization of the circadian rhythm can even not be achieved by nifedipine in all cases.