Differential association of retinal arteriolar and venular caliber with diabetes and retinopathy
Introduction
Diabetes mellitus (DM) is a major cause of morbidity and mortality in over 300 million people worldwide, with diabetic retinopathy being the commonest cause of preventable blindness in working aged adults, affecting 1 in 3 persons [1], [2], [3]. The magnitude of this problem is particularly striking in certain populations in Asia, with the number of Indians with diabetes expected to reach almost 80 million by year 2030 [4], and thus, every fifth person with diabetes will be an Indian. As compared to other Asian groups, such as Chinese and Malays, Indians develop diabetes at a younger age, have a higher lifetime risk of diabetes and are at a higher risk of complications despite treatment and follow-up adherence [5], [6], [7], [8].
The retinal vessels provide an opportunity to observe and study early microvascular changes in diabetes development. Recent studies show the caliber of the retinal vessels can be measured quantitatively from photographs, and variations in caliber are associated with diabetes, diabetic retinopathy and hyperglycemia, suggesting that retinal vascular caliber may be a surrogate marker of diabetes and its complications [9], [10], [11], [12], [13], [14], [15]. However, the relationship between retinal vascular caliber with diabetes and retinopathy has not been consistently reported in different racial/ethnic groups. Studies in white populations and a Singapore Malay population showed that wider retinal arterioles were associated with diabetes [11], [12], [13], [14]. However, in the Multi-Ethnic Study of Atherosclerosis (MESA) study, retinal arteriolar caliber was not associated with diabetes in non Whites and there were significant ethnic variations in the association between diabetes and retinal vascular calibers. In another multiethnic Asian population study, diabetes was associated with increasing retinal arteriolar calibers but this relationship was not statistically significant in individual ethnic groups [15]. Studies also suggested inconsistency in the relationship between retinal vascular caliber with microvascular complications such as diabetic retinopathy in different racial groups [11], [12], [13], [14].
Because Asian Indians have a higher prevalence of diabetes and risk of diabetic microvascular complications, it is informative to examine these relationships in this ethnic group. A previous study with a small number of ethnic Indians (n = 727) did not find statistically significant relationships between retinal vascular caliber and diabetes when stratified by ethnic groups [15]. To date, no studies have examined the relationship between retinal vascular caliber and diabetic retinopathy in ethnic Indians. The purpose of this study is therefore to determine the relationship of retinal vascular caliber with diabetes and to its primary microvascular complication, diabetic retinopathy in an Asian Indian population residing in Singapore.
Section snippets
Study population
The Singapore Indian Eye Study (SINDI) is a population-based cross-sectional survey of 3400 (75.6% response rate) ethnic Indians aged 40–80 years and living in Singapore. Data was collected from May 2007 through December 2009. Subjects were selected using an age-stratified (by 10-year age group) random sampling method, from a computer-generated list provided by the Singapore Ministry of Home Affairs. Detailed methodology has been described elsewhere [16], [17]. Written, informed consent was
Results
Of the 3400 participants, 3395 (99.9%) had fundal photographs. We excluded the subjects with ungradable retinal fundus photographs (n = 193) due to poor image quality or those without at least six large gradable arterioles or venules, and those with missing data on diabetic and diabetic retinopathy status (n = 119). We also excluded the subjects with proliferative diabetic retinopathy (n = 19) and subjects with previous laser treatment (n = 21), as this could have an effect on retinal vascular caliber
Discussion
In this large population-based study, we examined the variation of retinal vascular caliber in association with diabetes, retinopathy status and glycemia among Asian Indians residing in Singapore. To our knowledge, our study is the largest Indian population (3400 ethnic Indians) to examine correlates of retinal vascular caliber with diabetes and retinopathy and possible effect modification by cardiovascular risk factors. We showed that a wider retinal arteriolar caliber was related to diabetic
Funding
Biomedical Research Council (BMRC), 08/1/35/19/550.
Conflict of interest
The authors declare that they have no conflict of interest.
References (40)
- et al.
Diabetic retinopathy
Lancet
(2010) - et al.
Microvascular diabetic complications are more prevalent in India compared to Mauritius and the UK due to poorer diabetic control
Diabetes Res Clin Pract
(2009) - et al.
Low risk threshold for acquired diabetogenic factors in Asian Indians
Diabetes Res Clin Pract
(2004) - et al.
Retinal vascular caliber in persons with type 2 diabetes: the Wisconsin Epidemiological Study of diabetic retinopathy: XX
Ophthalmology
(2006) - et al.
Retinal vascular caliber, diabetes, and retinopathy
Am J Ophthalmol
(2007) - et al.
Computer-assisted measurement of retinal vessel diameters in the Beaver Dam Eye Study: methodology, correlation between eyes, and effect of refractive errors
Ophthalmology
(2004) - et al.
Retinal vascular abnormalities in persons with type 1 diabetes: the Wisconsin Epidemiologic Study of Diabetic Retinopathy: XVIII
Ophthalmology
(2003) - et al.
Retinal vascular manifestations of metabolic disorders
Trends Endocrinol Metab
(2006) - et al.
Lipid hydroperoxide stimulates leukocyte-endothelium interaction in the retinal microcirculation
Exp Eye Res
(2002) - et al.
The Wisconsin Epidemiologic Study of diabetic retinopathy. XIII. Relationship of serum cholesterol to retinopathy and hard exudate
Ophthalmology
(1991)