Effect of Captopril on Aqueous Levels of Angiotensin II in Diabetic Patients

To determine whether angiotensin II levels in aqueous humor is related to diabetes mellitus and to evaluate the effect of captopril.

In a case-control study, aqueous humor samples were obtained during cataract surgery from 58 eyes of 58 patients, of which 37 were diabetic. From these latter subjects, 16 had taken captopril (captopril group) and 21 had not taken any angiotensin converting enzyme (ACE) inhibitor (non-captopril group). Angiotensin level was assessed by radioimmunoassay. Severity of macular edema was evaluated by clinical examination after surgery. Mann Whitney U test was used to assess the statistical difference of mean angiotensin II and Hb A1C levels between the groups and Spearman's rank-order correlation coefficient was used to evaluate the correlation between aqueous levels of angiotensin II and severity of macular edema.

The aqueous level of angiotensin II was significantly higher in diabetic patients (31.07.3 pg/ml) compared to non-diabetics (6.282.8 pg/ml). (P<0.0001) Aqueous concentration of angiotensin II in the captopril group (16.36.5 g/ml) was significantly lower than in the non-captopril group (75.739.36). (P<0.0003) Severity of macular edema was significantly lower in the captopril group as compared to the non-captopril group such that 68.75% of the captopril group vs 33.3% of the non-captopril group had no macular edema (P<0.005).

These findings suggest that the aqueous level of angiotensin II is significantly correlated with the severity of macular edema and may have a role in pathogenesis of macular edema in diabetic patients. It seems that modulation of the renin-angiotensin system may become a very important target for medical treatment in patients with diabetic macular edema.