Aims/hypothesis: It has been suggested that aldosterone plays a role in the initiation and progression of renal disease independently of arterial blood pressure and plasma angiotensin II levels. We evaluated the influence of plasma aldosterone levels on progression of diabetic nephropathy during long-term blockade of the renin-angiotensin-aldosterone system.
Methods: A total of 63 hypertensive patients with type 1 diabetes and diabetic nephropathy were treated with losartan, 100 mg once daily, for a mean follow-up period of 35 months. Plasma aldosterone, GFR, albuminuria and 24-h blood pressure were determined at baseline and at regular intervals during the study.
Results: Patients were divided according to their increasing or decreasing levels of plasma aldosterone during long-term losartan treatment in an escape group (n=26) and a non-escape group (n=37). In the escape group, aldosterone levels increased from (geometric mean [95% CI]) 57 pg/ml (43-76 pg/ml) at 2 months, to 102 pg/ml (78-134 pg/ml) at the end of the study (p<0.01). The corresponding levels in the non-escape group were 83 pg/ml (69-102 pg/ml) and 49 pg/ml (40-60 pg/ml; p<0.01). The median rate of decline in GFR was 5.0 ml.min(-1).year(-1) (range 0.4-15.9 ml.min(-1).year(-1)) in the escape group, compared with 2.4 ml.min(-1).year(-1) (-1.6 to 11.0 ml.min(-1).year(-1)) in the non-escape group (p<0.005). The increase in plasma aldosterone correlated with the rate of decline in GFR (r(2)=0.19, p<0.001), corresponding to a decline in GFR of 1.5 ml.min(-1).year(-1) for every two-fold increase in plasma aldosterone. Pre-treatment and treatment values of plasma aldosterone were not related to albuminuria or to changes in albuminuria during the study.
Conclusions/interpretation: Our data suggest that aldosterone escape during long-term blockade of the renin-angiotensin-aldosterone system is associated with an enhanced decline in GFR in patients with type 1 diabetes and diabetic nephropathy.