Angiotensin blockade to reduce microvascular damage in diabetes mellitus

Diabetic retinopathy and microalbuminuria are often thought of as distinct disease entities despite their common pathophysiology. Many studies have addressed the prognostic significance of these conditions and their treatment.

Medline was selectively searched for articles published from 1948 to 2008 containing the terms "angiotensin," "microalbuminuria," and "retinopathy." The results were further amplified by screening the reference sections of the retrieved articles.

Diabetic retinopathy and microalbuminuria are expressions of microvascular damage. They are promoted by hypertension, hyperglycemia, dyslipidemia, and elevated levels of angiotensin II. They are treated by adjusting these risk factors to the near-normal range. In the IDNT study, angiotensin II blockade with irbesartan was found to lead to an absolute reduction of renal events by 7.4% as compared to standard treatment, and by 9.5% as compared to amlodipine. In the DIRECT study, candesartan reduced the progression of retinopathy by 13% and effected a regression by 34%. In the Steno-2 study, an intensive program of multifactorial risk reduction significantly lowered the rate of microvascular complications over a mean follow-up interval of 3.8 years (hazard ratios for different complications varying from 0.27 to 0.45). Over the longer term (13.3 years), this approach also led to a reduction of macrovascular events (HR 0.54 for mortality of all causes, 0.43 for cardiovascular mortality, and 0.41 for cardiovascular events).

Diabetic retinopathy and microalbuminuria are expressions of microvascular damage. They often appear together and point toward possible future macrovascular events. Multifactorial intervention can lessen the consequences of these pathological conditions.