Early ACE-i intervention in microalbuminuric patients with type 1 diabetes: effects on albumin excretion, 24 h ambulatory blood pressure, and renal function

Abstract

Objectives: To study the effects of ACE-i in type 1 diabetic patients with early microalbuminuria with regard to: i) UAE, ii) 24 h AMBP, including the effect on diurnal BP variation, and iii) renal haemodynamics.

Material and methods: 58 patients with urinary albumin excretion (UAE) between 20-70 microg/min were treated for two years with either the ACE inhibitor (ACE-i) lisinopril (20 mg od) or placebo in two randomised placebo controlled double blind studies. In a subgroup of patients (n=22) we performed 24 h ambulatory blood pressure measurements (AMBP) and renal function tests (constant infusion technique).

Results: i) Changes in UAE over the two years were significantly different (p<0.01) in the two groups with final UAE in the lisinopril group of 19.1 microg/min x/divide 2.5 (geometric mean x/divide tolerance factor) and 44.1 microg/min x/divide 2.8 in the placebo group. In the lisinopril group 20 patients (60.6%) reversed to normoalbuminuria compared to 6 patients (24%) in the placebo group (p<0.02). ii) Clinical BP measurements revealed no differences between groups, but by AMBP significant reductions were detectable in the lisinopril group, primarily in night AMBP (systolic/diastolic: - 6.9 +/- 8.6/- 6.0 +/- 5.3 mmHg, p<0.01) as opposed to increases in the placebo group (3.1 +/- 9.3/1.9 +/- 7.3 mmHg). iii) Changes in UAE and changes in filtration fraction (FF) were positively correlated in the intervention group (r=0.9, p<0.01), i.e. the patients who showed the greatest fall in UAE were the ones with the greatest fall in FF.

Conclusions: ACE-i treatment in patients with low-grade microalbuminuria reduces 24 h AMBP without attenuating diurnal blood pressure variation, reduces UAE significantly, with changes in UAE being strongly associated with changes in FF. Furthermore, compared to placebo, ACE-i reverses micro- to normoalbuminuria in a significant fraction of patients.