Effect of enalapril on the microvascular albumin leakage in patients with diabetic microangiopathy and normal or mildly elevated blood pressure

The transcapillary escape rate of albumin (TERalb) is often elevated in patients with diabetic microangiopathy. The objective of this study was to examine the effect of enalapril on the TERalb of diabetic patients with albuminuria and normal or mildly elevated blood pressure. Seventeen diabetic patients with diabetic retinopathy, albuminuria, a diastolic blood pressure below 100 mmHg and increased TERalb participated in the study. Blood pressure and TERalb were measured before and after 14 days of therapy with enalapril, 20 mg daily for 14 days. Systolic and diastolic blood pressure fell from 168 ± 6 to 155 ± 6 (p <0.001) and from 87 ± 2 to 81 ± 2 mmHg (p <0.005) respectively. Mean arterial pressure declined from 114 ± 3 to 105 ± 3 mmHg (p <0.0001). The elevated TERalb decreased from 9.5 ± 0.5 to 7.2 ± 0.5% /hr (p <0.005). In the hypertensive subset, systolic, diastolic and mean arterial pressure decreased significantly by 15, 7 and 10 mmHg (p <0.005, p <0.005 and p <0.005 respectively); TERalb decreased from 9.5 ± 0.6 to 7.3 ± 0.6 (p <0.03). In the normotensive subset, arterial pressure remained unchanged and TERalb decreased from 9.0 ± 0.8 to 6.8 ± 1.0% /hr (p <0.03). Plasma fructosamine decreased from 373 ± 23 to 347 ± 20 (p <0.05) in the hypertensive group and remained unchanged in the normotensive patients. No correlation could be demonstrated between variation in TERalb and changes in blood pressure. In conclusion, enalapril decreases microvascular albumin leakage in patients with diabetic microangiopathy and normal or mildly elevated blood pressure.