Stabilization of glomerular filtration rate over 2 years in patients with diabetic nephropathy under intensified therapy regimes

OBJECTIVES: We investigated the effect of achieved continuous tight blood pressure control and intensified insulin therapy on the rate of progression of renal failure in patients with overt diabetic nephropathy and already impaired renal function. DESIGN AND SETTING: Prospective, randomized, multicentre, follow-up study. PATIENTS AND INTERVENTIONS: From a screened group of the 66 hypertensive type 1 diabetic patients (IDDM) with overt diabetic nephropathy and reduced glomerular filtration rate who participated in two intensified treatment programmes, 39 patients fulfilled the study inclusion criteria and were enrolled into the 2-year follow-up period. The choice of antihypertensive drugs was based on a randomized allocation to open antihypertensive treatments starting with felodipine, metoprolol, or ramipril. OUTCOME MEASURES: Progression of renal failure was assessed by measurement of glomerular filtration rate (GFR) on insulin clearance every 6 months. MAIN RESULTS: During the study period mean HbA1c was 8.1 +/- 1.6% and the office blood pressure 143 +/- 14/88 +/- 8 mmHg. The change in GFRinulin (mean and 95% CI) was +1.9 (-2.2; +6.1) ml/min/year. GFR improved in 51%, deteriorated in 39%, and remained stable in 10% of the patients. CONCLUSION: This study shows that stabilization of glomerular filtration rate, as assessed by inulin clearance, is possible in patients with overt diabetic nephropathy who reach the goals of intensified antihypertensive treatment even if kidney function is already impaired.