Biologic Risk Factors Associated with Diabetic Retinopathy: the Los Angeles Latino Eye Study

Objective: To identify biologic risk factors associated with having diabetic retinopathy (DR) in Latinos with type 2 diabetes mellitus (T2DM).

Design: Population-based cross-sectional study.

Participants: Six thousand three hundred fifty-seven Latinos ages > or =40 years from 6 census tracts in Los Angeles, California.

Methods: An in-home interview was administered to all participants in the Los Angeles Latino Eye Study (LALES). All participants diagnosed with T2DM underwent a complete ophthalmologic examination including stereoscopic fundus photography (7 standard Early Treatment Diabetic Retinopathy Study fields). Photographs were graded in a masked manner using a modified Airlie House grading system to assess presence and severity of DR. Univariate and stepwise logistic regression analyses were used to identify independent risk factors.

Main Outcome Measures: Biologic risk factors associated with any DR and proliferative DR (PDR).

Results: Of the 7789 eligible individuals in LALES, 6357 (82%) had a clinical examination. One thousand two hundred sixty-three participants had definite diabetes and 1187 Latinos had T2DM. Of those with T2DM, 46% (544) had DR. Stepwise logistic regression analyses revealed that compared with females, males had a 50% higher risk of having any DR (OR = 1.50; P = 0.006). Factors independently associated with a greater risk of having any DR were longer duration of known diabetes (per year, OR = 1.08, P<0.0001), higher glycosylated hemoglobin levels (per 1%, OR = 1.22, P<0.0001); higher systolic blood pressure (per 20 mmHg, OR = 1.26, P = 0.002); and insulin treatment (OR = 1.60, P = 0.01). Factors independently associated with PDR included longer duration of known diabetes (per year, OR = 1.06, P<0.0001); being on insulin treatment (OR = 3.2, P<0.0001); and a higher systolic blood pressure (per 20 mmHg, OR = 1.44, P = 0.01). The relationship of these variables to the risk of having DR or PDR is not a constant linear function in all cases and varies depending on the variable.

Conclusions: Our study showed that the high risk of DR in adult Latinos is independently associated with both nonmodifiable and modifiable risk factors. These findings suggest that controlling hyperglycemia and hypertension in this ethnic group may reduce the high risk of having DR associated with T2DM.