Increased plasma renin activity in type 1 diabetes with microvascular disease.

Plasma renin activity was measured in thirty-one subjects with Type 1 diabetes and proliferative retinopathy, and in seventeen matched diabetic subjects without evidence of any complications of their disease. The two groups were comparable for age, sex, smoking habits and duration of diabetes. Systolic and diastolic blood pressures were significantly higher in the patients with retinopathy (P less than 0.025 and P-0.05 respectively) and HbA1 was greater (P less tha 0.005) than in the patients without complications. Plasma renin activity, both lying and standing, was higher in the patients with retinopathy than in the uncomplicated group (P less than 0.05 for each). There were no correlations between plasma renin activity and mean blood pressure, HbA1 or fasting blood glucose. These findings raise the possibility that the renin-angiotensin system might be implicated in the pathogenesis of diabetic microvascular.