Abstract
Purpose: :
To examine the relationships of serum markers of inflammation and endothelial dysfunction (high sensitive C reactive protein [CRP], soluble e-selectin, ICAM-1, VCAM-1, endothelin-1, and total nitrite) to presence and severity of diabetic retinopathy (DR).
Methods: :
We recruited 224 participants with diabetes (85 type 1, 139 type 2), aged <70 years. Clinical and blood examinations and retinal photography were performed following standardized protocols. DR was graded from fundus photographs using Airlie House Classification system and categorized into no DR, mild non-proliferative DR (NPDR), moderate NPDR and vision threatening DR (VTDR), comprising severe non-proliferative DR or proliferative. We assessed associations between serum markers and severity of DR using ordinal logistic regression.
Results: :
There were 64% (144) participants with DR and 25% (57) with VTDR. Persons with DR had longer diabetes duration, higher HbA1c and systolic blood pressure (SBP), and were more likely to use insulin than those without DR. Persons with VTDR had longer diabetes duration, higher fasting glucose, SBP, body mass index (BMI) and CRP levels than those without VTDR. After controlling for age, gender, duration of diabetes, HbA1c, SBP, cholesterol, smoking, and the use of insulin or diabetes drugs, increasing CRP levels were associated with increasing severe levels of DR (odds ratio [OR] 1.23; 95% Confidence Interval [CI] 1.02 - 1.49, per SD increase in CRP), or with presence of VTDR (OR 1.38; 95% CI 1.07 - 1.68, per SD increase in CRP). After stratifying by BMI (≥30 and <30), this association was only significant in those with BMI≥30.
Conclusions: :
Higher CRP levels, but not markers of endothelial activation, were related to more severe DR levels. This suggests that inflammation may be more important as a pathogenic factor than endothelial dysfunction in DR, particularly in obese persons with diabetes.
Keywords: diabetic retinopathy • inflammation • clinical (human) or epidemiologic studies: risk factor assessment