Ryan Eyn Kidd Man1, Charumathi Sabanayagam2, Peggy Pei-Chia Chiang3, Ling-Jun Li2, Jonathan Edward Noonan4, Jie Jin Wang5, Tien Yin Wong6, Gemmy Chui-Ming Cheung7, Gavin Siew Wei Tan7, Ecosse L Lamoureux8. 1. Singapore Eye Research Institute, Singapore National Eye Centre, Singapore. 2. Singapore Eye Research Institute, Singapore National Eye Centre, Singapore2Duke-National University of Singapore Graduate Medical School, Singapore. 3. Centre for Health Equity, Melbourne School of Population and Global Health, University of Melbourne, Melbourne, Victoria, Australia. 4. Centre for Eye Research Australia, University of Melbourne, Melbourne, Victoria, Australia. 5. Centre for Vision Research, Westmead Millennium Institute for Medical Research, University of Sydney, Sydney, New South Wales, Australia. 6. Singapore Eye Research Institute, Singapore National Eye Centre, Singapore2Duke-National University of Singapore Graduate Medical School, Singapore6Singapore National Eye Centre, Singapore. 7. Singapore National Eye Centre, Singapore. 8. Singapore Eye Research Institute, Singapore National Eye Centre, Singapore2Duke-National University of Singapore Graduate Medical School, Singapore4Centre for Eye Research Australia, University of Melbourne, Melbourne, Victoria, Australia.
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 for age, 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 (P for interaction = .006). No sex-specific associations were found between BMI and DR (P for 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.
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 for age, 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 (P for interaction = .006). No sex-specific associations were found between BMI and DR (P for 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.