A randomized controlled trial on the efficacy and safety of combination therapy by amlodipine and irbesartan for delaying the progression of diabetic nephropathy

INTERVENTION: A:Combination therapy of amlodipine 5mg and irbesartan 150mg, orally take once for 8 weeks;B:Irbesartan 300mg, orally take once for 8 weeks; CONDITION: Diabetic nephropathy E11. 2 PRIMARY OUTCOME: ACR change rate;Effective rate; SECONDARY OUTCOME: GFR;Mortality;ACR;Urine protein in 24 hrs;Metabolic conditions;Blood pressure;PCR;The incidence of heart and cerebral vaslular event; INCLUSION CRITERIA: 1. Diagnosed as type 2 diabetes mellitus according to the criteria of ADA, 1997; 2. Diagnosed as diabetic nephropathy according to the criteria of KDOQI, 2007; 3. Aged betweeen 18 and 70 years old; 4. No restrition on gender; 5. With persistent macroalbuminuria: ACR > 300 mg/g, and/or proteinuria > 300 mg/24hrs; and protenuria < 3.5 g/24hrs; serum albumin > 30 g/L; 6. GFR > 60ml/min,or seum creatinine < 2.0 mg/L; 7. SBP > 140 mmHg and/or DBP > 90 mmHg before the washout of irbesartan; or the patients need antihypertensive therapy; 8. Stable metabolic control for at least 3 months: HbA1c<8.5%,fasting blood glucose <10mmol/L (controlled by oral hypoglycemic drugs or insulin); 9. Serum potassium 3.5 5.5 mmol/L; 10. Informed consents obtained.