Few studies have reported the effect of alpha1-adrenergic antagonists on 24-h blood pressure and regulation of sympathetic nervous activity in hypertensive patients with diabetic nephropathy. Using ambulatory blood pressure monitoring devices equipped with spectral analysis of heart rate variability, we assess the effects of doxazosin on blood pressure in diabetic nephropathy patients and compare the results with those in patients with essential hypertension, patients with diabetes mellitus and patients with chronic nephropathy.

The study is an open-labeled parallel prospective trial comparing the effects of doxazosin (2-8 mg/day) on 24-h blood pressure and autonomic nervous activity. Hypertensive patients with non-insulin-dependent diabetic nephropathy, patients with essential hypertension, patients with diabetes mellitus and patients with chronic nephropathy undergo ambulatory blood pressure monitoring before and after treatment with doxazosin. Simultaneously, spectral analysis is performed to calculate the high frequency components as a marker of parasympathetic nervous activity, and the low frequency components/high frequency components ratios as an index of the sympathovagal balance.

Inclusion Criteria:

• Hypertensive patients with diabetes mellitus
• Hypertensive patients
• Hypertensive patients with renal disease

Exclusion Criteria:

• Cardiac, hematologic or hepatic disease
• Renal insufficiency (serum creatinine values> 2 mg/L)
• Hormone-induced hypertension
• Cerebral infarction or hemorrhage
• Other major diseases