Abstract
Purpose: :
To assess the relationship of the albuminuria with the severity of diabetic retinopathy (DR) and macular edema (DME) in patients with type 2 diabetes.
Methods: :
Prospective clinical case series among patients with type 2 diabetes were recruited from a tertiary eye clinic in Melbourne, Australia. A spot urine sample was collected to determine albumin-creatinine ratio (ACR). ACR was analyzed as a continuous variable and also as a categorical variable namely normo- (ACR<30), micro- (30≤ACR<300) and macro-albuminuria (ACR≥300). DR was graded from fundus photographs using the modified Airlie House classification system, and categorized into mild, moderate and vision-threatening DR (VTDR, including severe non-proliferative and proliferative DR). DME was graded from the same photographs according to the American Academy of Ophthalmology criteria.
Results: :
A total of 389 patients [median age (range) = 66 years (59-74)] were analyzed, of which 223 (58.9%) had any DR and 155 (41.0%) had any DME. 333 (85.6%), 49 (12.6%) and 7 (1.8%) participants had normo-, micro- and macro-albuminuria, respectively. ACR was higher in participants with than without DR (3.2 vs. 1.3 mg/mmol, P=0.01). Adjusting for age, gender, duration of diabetes, HbA1c, and blood pressure; higher ACR was associated with any DR (odds ratio [OR] 2.34; 95% CI: 1.17 - 4.67, per standard deviation (SD) increase in ACR) and VTDR (OR 3.09; 95% CI:1.48 - 6.42). Persons with micro- or macro-albuminuria were almost four times more likely to have VTDR (OR 3.59; 1.50 - 8.56; P=0.004) than those with normo-albuminuria. In contrast, no associations were found between (a) albuminuria and DME; and (b) those with and without DME with the same level of DR.
Conclusions: :
Type 2 diabetic patients with albuminuria were more likely to have DR, particularly severe DR. This suggests that the development of DR and albuminuria shares a common etiology. However, kidney impairment was not related to DME and may indicate that the pathophysiology of DME may be different to DR.
Keywords: diabetic retinopathy • edema • diabetes