Abstract
Diabetic retinopathy (DR) is a common cause of blindness. Although many studies have indicated an association between homocysteine and DR, the results so far have been equivocal. Amongst the many determinants of homocysteine, B-vitamin status was shown to be a major confounding factor, yet very little is known about its relationship to DR. In the present study, we, therefore, investigated the status of B-vitamins and homocysteine in DR. A cross-sectional case–control study was conducted with 100 normal control (CN) subjects and 300 subjects with type-2 diabetes (T2D). Of the 300 subjects with T2D, 200 had retinopathy (DR) and 100 did not (DNR). After a complete ophthalmic examination including fundus fluorescein angiography, the clinical profile and the blood levels of all B-vitamins and homocysteine were analyzed. While mean plasma homocysteine levels were found to be higher in T2D patients compared with CN subjects, homocysteine levels were particularly high in the DR group. There were no group differences in the blood levels of vitamins B1 and B2. Although the plasma vitamin-B6 and folic acid levels were significantly lower in the DNR and DR groups compared with the CN group, there were no significant differences between the diabetes groups. Interestingly, plasma vitamin-B12 levels were found to be significantly lower in the diabetes groups compared with the CN group; further, the levels were significantly lower in the DR group compared with the DNR group. Higher homocysteine levels were significantly associated with lower vitamin-B12 and folic acid but not with other B-vitamins. Additionally, hyperhomocysteinemia and vitamin-B12 deficiency did not seem to be related to subjects' age, body mass index, or duration of diabetes. These results thus suggest a possible association between vitamin-B12 deficiency and hyperhomocysteinemia in DR. Further, the data indicate that vitamin-B12 deficiency could be an independent risk factor for DR.
Highlights
Diabetic retinopathy (DR) is one of the most common microvascular complications of diabetes and ranks as a common cause of blindness worldwide [1,2]
We investigated the status of B-vitamins (B1, B2, B6, B12, folic acid) and homocysteine in DR. This is a hospital-based case-control study consisting of type 2 diabetes (T2D) subjects with (DR) and without retinopathy (DNR) along with normal control (CN) subjects
Amongst diabetes groups, glycosylated hemoglobin (HbA1c) levels were higher in DR compared to DNR (p,0.05)
Summary
Diabetic retinopathy (DR) is one of the most common microvascular complications of diabetes and ranks as a common cause of blindness worldwide [1,2]. Diabetic retinopathy could become a major threat to public health in the future due to the global prevalence of diabetes, which is projected to affect 438 million people by 2030 [3]. Both the duration of diabetes and its metabolic control have been identified as the risk factors most strongly associated with the development of DR [4,5]. The prevalence of DR in South India was reported to be 22.4% based on the Andhra Pradesh Eye Disease Study (APEDS) of selfreported diabetes [9]. The prevalence of DR was 0.5% in the general rural populations of South India and 10.5% among patients with diabetes [10]
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