Benefits of Renin-Angiotensin Blockade on Retinopathy in Type 1 Diabetes Vary With Glycemic Control

  1. for the Renin Angiotensin System Study (RASS) group
  1. 1Department of Medicine, University of Minnesota, Minneapolis, Minnesota
  2. 2Department of Pediatrics, University of Minnesota, Minneapolis, Minnesota
  3. 3Department of Ophthalmology and Visual Sciences, University of Wisconsin, Madison, Wisconsin
  4. 4Department of Medicine, University of Toronto, Toronto, Canada
  1. Corresponding author: Tasma Harindhanavudhi, hari0049{at}umn.edu.

Abstract

OBJECTIVE Optimal glycemic control slows diabetic retinopathy (DR) development and progression and is the standard of care for type 1 diabetes. However, these glycemic goals are difficult to achieve and sustain in clinical practice. The Renin Angiotensin System Study (RASS) showed that renin-angiotensin system (RAS) blockade can slow DR progression. In the current study, we evaluate whether glycemic control influenced the benefit of RAS blockade on DR progression in type 1 diabetic patients.

RESEARCH DESIGN AND METHODS We used RASS data to analyze the relationships between two-steps or more DR progression and baseline glycemic levels in 223 normotensive, normoalbuminuric type 1 diabetic patients randomized to receive 5 years of enalapril or losartan compared with placebo.

RESULTS Patients (147 of 223; 65.9%) had DR at baseline (47 of 74 patients [63.5%] in placebo and 100 of 149 patients [67.1%] in the combined treatment groups [P = 0.67]). Patients with two-steps or more DR progression had higher baseline A1C than those without progression (9.4 vs. 8.2%, P < 0.001). There was no beneficial effect of RAS blockade (P = 0.92) in patients with baseline A1C ≤7.5%. In contrast, 30 of 112 (27%) patients on the active treatment arms with A1C >7.5% had two-steps or more DR progression compared with 26 of 56 patients (46%) in the placebo group (P = 0.03).

CONCLUSIONS RAS blockade reduces DR progression in normotensive, normoalbuminuric type 1 diabetic patients with A1C >7.5%. Whether this therapy could benefit patients with A1C ≤7.5% will require long-term studies of much larger cohorts.

  • Received March 9, 2011.
  • Accepted April 25, 2011.

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  1. Diabetes Care
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