Decline of Renal Function Is Associated with Proteinuria and Systolic Blood Pressure in the Morning in Diabetic Nephropathy

Abstract

The aim of this study was to investigate a significance of increased proteinuria in the morning and the effects of antihypertensive treatment on proteinuria and arterial blood pressure in the progression of chronic renal insufficiency in type 2 diabetic patients with hypertension and nephropathy. In three 24-hr urine samples and blood pressure monitoring, separated into a night-and daytime and spot urine in the morning, variation in protein-creatinine ratio (g/g) and blood pressure were assessed in 24 (58 ± 3 years old; M/F: 17/7) diabetic patients with hypertension and nephropathy. Furthermore, the effects of antihypertensive therapy of combinations of angiotensin converting enzyme (ACE) inhibitor, calcium antagonists, diuretics, and α1 blocker were evaluated in 3 years. Home blood pressure measurement was carried out every month and 24-hr urine was collected every 2 months. The baseline urine excretion of protein-creatinine ratio and blood pressure were (1.22 ± 0.13 g/g creatinine: 154/96 ± 6/5 mmHg) in daytime and (1.39 ± 0.13: 168/88 ± 15/7) in the morning. At the end of the study, significant associations among a decline of 24-hr creatinine clearance and both of the urine excretion of protein-creatinine ratio (r = 0.47, p < .01) and the levels of systolic blood pressure (r = 0.46, p < .01) and between the levels of systolic blood pressure and the urine excretion of protein-creatinine ratio in the morning (r = 0.57, p < .001) were demonstrated. However, there were no significant associations among other variables. Analysis of patients who had systolic blood pressure in the morning less than 140 mmHg revealed that 65% of these patients received doxazosin-averaged doses of 4.8 ± 1.5 mg daily. The levels of both blood pressure and proteinuria-creatinine ratio in the morning mainly associate with progression of renal function in diabetic patients with hypertension and nephropathy.