Long-term renoprotective effects of losartan in diabetic nephropathy

OBJECTIVE - Several observational follow-up studies have found that the D allele of the insertion (1)/deletion (D) polymorphism of the ACE gene (ACE/ID) is associated with an increased risk of renal function loss, even during ACE inhibition. Therefore, we investigated the long-term effect Of the angiotensin II subtype-1 (AT1) receptor antagonist losartan (100 mg o.d. on kidney function in II and DD type 1 diabetic Patients with diabetic nephropathy. RESEARCH DESIGN AND METHODS - A total of 54 hypertensive type 1 diabetic patients with diabetic nephropathy homozygous for the insertion (n = 26) or the deletion (n = 28) allele were included in the study. After a 4-week washout, the patients received losartan (tablet, 100 mg o.d.) and were followed prospectively with a mean follow-up period of 36 months. Patients and investigators were blinded to ACE genotypes. At baseline, after 2 and 4 months and every 6 months thereafter, glomerular filtration rate (GFR), albuminuria, and 24-h blood pressure were determined. RESULTS- At baseline, GFR, albuminuria, and blood pressure were similar in the two genotype groups, II versus DD: mean (SD), 86 (22) vs. 88 (24) ml (.) min(-1) (.) -1.73 m(-2); median (interquartile range), 1,134 (598-2,023) vs. 1,451 (893-1,766) mg/24 h; and mean (SD), 156/82 (17/9) vs. 153/80 (17/11) mmHg, respectively. GFR decreased similarly In both genotype groups, versus DD, respectively (P = 0.4): geometric mean (95% CI), 2.9 (2.0-4.2) vs. 3.4(2.3-5.1)ml (.) min(-1.)year(-1.) Albuminuria and arterial blood pressure were significantly reduced during the study; no differences were noted between groups. During follow-up, albiminuria was decreased by 75% (95% CI 59-85) and 73% (56-83) in the II and DD groups, respectively (P <0.01 vs. baseline). Mean systolic and diastolic blood pressures were 139/74mmHg(14/8) in both genotype groups during the study (P < 0.01 vs. baseline). CONCLUSIONS - In contrast to previous observational studies with ACE inhibitors, longterm treatment with losartan has similar beneficial renoprotective effects on progression of diabetic nephropathy in hypertensive type 1 diabetic patients with ACE II and DD genotypes.