Differential association of generalized and abdominal obesity with diabetic retinopathy in Asian patients with type 2 diabetes

Abstract

IMPORTANCE: The association between obesity and diabetic retinopathy (DR) is equivocal, possibly owing to the strong interrelation between generalized and abdominal obesity leading to a mutually confounding effect. To our knowledge, no study in Asia has investigated the independent associations of these 2 parameters with DR to date. OBJECTIVE: To investigate the associations of generalized (defined by body mass index [BMI], calculated as weight in kilograms divided by height in meters squared) and abdominal obesity (assessed by waist to hip ratio [WHR]) with DR in a clinical sample of Asian patients with type 2 diabetes mellitus. DESIGN, SETTING, AND PARTICIPANTS: This cross-sectional clinic-based study was conducted at the Singapore National Eye Centre, a tertiary eye care institution in Singapore, from December 2010 to September 2013. We recruited 498 patients with diabetes. After exclusion of participants with ungradable retinal images and type 1 diabetes, 420 patients (mean [SD] age, 57.8 [7.5] years; 32.1% women) were included in the analyses. EXPOSURES: Body mass index and WHR as waist/hip circumference (in centimeters). MAIN OUTCOMES AND MEASURES: The presence and severity of DR were graded from retinal images using the modified Airlie House Classification into none (n = 189), mild-moderate (Early Treatment Diabetic Retinopathy Study scale score, 20-41; n = 125), and severe DR (Early Treatment Diabetic Retinopathy Study scale score ≥53; n = 118). The associations of BMI and WHR with DR were assessed using multinomial logistic regression models adjusting forage, sex, traditional risk factors, and mutually for BMI and WHR. RESULTS: Among the total of 420 patients, the median (interquartile range) for BMI and WHR were 25.7 (5.7) and 0.94 (0.08), respectively. In multivariable models, BMI was inversely associated with mild-moderate and severe DR (odds ratio [OR], 0.90 [95% CI, 0.84-0.97] and OR, 0.92 [95% CI, 0.85-0.99] per 1-unit increase, respectively), while WHR was positively associated with mild-moderate and severe DR (OR, 3.49 [95% CI, 1.50-8.10] and OR, 2.68 [95% CI, 1.28-5.62] per 0.1-unit increase, respectively) in women (Pfor interaction = .006). No sex-specific associations were found between BMI and DR (Pfor interaction >.10). CONCLUSIONS AND RELEVANCE: In Asian patients with type 2 diabetes, a higher BMI appeared to confer a protective effect on DR, while higher WHR was associated with the presence and severity of DR in women. Our results may inform future clinical trials to determine whether WHR is a more clinically relevant risk marker than BMI for individuals with type 2 diabetes.