Diabetes and diabetic retinopathy: the growing public health concerns in India
Authors: Suraj Singh Senjam
Journal: The Lancet Global Health (2024)

Globally, diabetic retinopathy, along with diabetes, has been a growing concern over the past few decades, especially in low-income and middle-income countries. It is widely recognised that diabetic retinopathy is one of the major causes of visual impairment, especially in the adult population. India is accountable for one of seven adults living with diabetes worldwide. The 10th edition of the International Federation Diabetes Atlas 2021 estimates that there are 74 million people aged 20–79 years affected by diabetes in India, and this number is expected to increase to 125 million by 2045.1International Diabetes Federation10th Edition Diabetes Atlas.https://diabetesatlas.org/idfawp/resource-files/2021/07/IDF_Atlas_10th_Edition_2021.pdfDate: 2021Date accessed: January 31, 2024Google Scholar This reflects that the prevalence of diabetic retinopathy will substantially increase over time, along with associated vision loss. Furthermore, the existing diabetic retinopathy burden will also be exacerbated by a high proportion of undiagnosed diabetes in India.2Gupta V Azad SV Vashist P Senjam SS Kumar A Diabetic retinopathy screening in the public sector in India: what is needed?.Indian J Ophthalmol. 2022; 70: 759-767Crossref PubMed Scopus (1) Google Scholar Given the rapid epidemiological and demographic transition observed in low-income and middle-income countries, there is a strong indication that conducting a population-based epidemiological study of diabetic retinopathy periodically is of crucial importance in understanding the trends of the problem. Although data are available from a national survey conducted in 2015–19 that estimates the prevalence of sight-threatening diabetic retinopathy and its risk factors, the current national representative, the SMART-India study, provides additional literature on the associated risk factors for visual impairment and blindness among people with diabetes.3Gurudas S Vasconcelos CJ Prevost AT et al.National prevalence of vision impairment and blindness and associated risk factors in adults aged 40 years and older with known or undiagnosed diabetes: results from the SMART-India cross-sectional study.Lancet Glob Health. 2024; (published online Feb 28.)https://doi.org/10.1016/S2214-109X(24)00035-4Google Scholar Even though diabetic retinopathy is a risk factor for visual loss in people with diabetes, the prevalence of any visual impairment is much higher among participants with ungradable diabetic retinopathy (29·2%) than participants with gradable diabetic retinopathy (19·6%), as indicated in the present study. The same is true among participants with blindness. This ungradable diabetic retinopathy is due to media opacity, most commonly attributed to senile cataract. Therefore, in India, reducing cataracts causing visual impairment continues to be a priority, especially in people with diabetes, as there is no dispute that cataracts remain the most common cause of vision loss in the Indian adult population.4Vashist P Senjam SS Gupta V et al.Blindness and visual impairment and their causes in India: results of a nationally representative survey.PLoS One. 2022; 17e0271736Crossref Scopus (26) Google Scholar Gurudas and colleagues recommended that reducing visual impairment attributed to diabetic retinopathy would have a substantial effect on the rates of visual impairment and blindness, especially in older populations and poor and underprivileged communities. Vision loss due to diabetic retinopathy is irreversible, therefore early detection followed by timely therapeutic intervention can prevent people living with diabetes and with mild to severe vision loss (less than 6/18 to 3/60) from progressing into blindness. The study highlights that known diabetes is a predictor for the presence of sight-threatening diabetic retinopathy, whereas this is not the case for unknown diabetes, therefore early detection and intervention can be prioritised first among those with a known diagnosis of diabetes in India. The authors also reported that many people with diabetes with poor vision had ungradable retinal images, possibly due to media opacity, therefore the severity of diabetic retinopathy in these participants was unknown. These participants with ungradable retinal images need to be followed-up to assess the severity of the diabetic retinopathy, after appropriate management for media opacity, such as senile cataract. Nowadays, there are many hand-held non-mydriatic fundus cameras available that can be used for community diabetic retinopathy screening in low-resource settings.5Nakayama LF Ribeiro LZ Gonçalves MB et al.Diabetic retinopathy classification for supervised machine learning algorithms.Int J Retin Vitr. 2022; 8: 1Crossref PubMed Scopus (9) Google Scholar Gurudas and colleagues used digital retinal imaging with a non-mydriatic fundus camera to capture retinal images in all people with diabetes. It is important to highlight the validity, accuracy, or performance of such a camera. Using ophthalmoscopy, as mentioned in Rapid Assessment of Avoidable Blindness (RAAB) 2015–19, might not be feasible for mass community diabetic retinopathy screening because ophthalmologists are required to operate ophthalmoscopes. For a low-resource setting such as India, there is a need for diabetic retinopathy screening standardisation, including a recommended grading system with a reliable and cost-effective hand-held non-mydriatic fundus camera. Additional investigation is needed to decide whether the present diabetic retinopathy grading scale will be feasible in low-resource settings by a non-ophthalmologist. There are other grading systems such as The Scottish Grading protocol that can be used by non-ophthalmologists.6Zachariah S Wykes W Yorston D Grading diabetic retinopathy (DR) using the Scottish grading protocol.Community Eye Heal. 2015; 28: 72PubMed Google Scholar, 7Wadhwani M Vashist P Singh SS et al.Diabetic retinopathy screening programme utilising non-mydriatic fundus imaging in slum populations of New Delhi, India.Trop Med Int Health. 2018; 23: 405-414Crossref PubMed Scopus (13) Google Scholar This protocol was used in the RAAB India survey conducted in 2015–19.8Vashist P Senjam SS Gupta V et al.Prevalence of diabetic retinopahty in India: results from the National Survey 2015–19.Indian J Ophthalmol. 2021; 69: 3087-3094Crossref PubMed Scopus (14) Google Scholar Such various diabetic retinopathy grading protocols can create a fundamental problem in standardising community screening activities in low-resource areas, especially in areas in which only few ophthalmologists are available. Further work will be required to develop a uniform protocol for low-resource settings employing non-ophthalmologists to grade diabetic retinopathy. A uniform protocol that includes appropriate technology and a diabetic retinopathy screening scale will be helpful in the integration of the screening programme into the existing health-care delivery system. Additionally, it is also important to ensure open access to images from a reliable screening model. Introducing artificial intelligence-based diabetic retinopathy screening might be worthwhile and sustainable considering the increased amount of patients with diabetic retinopathy in the country.9Grauslund J Diabetic retinopathy screening in the emerging era of artificial intelligence.Diabetologia. 2022; 65: 1415-1423Crossref PubMed Scopus (22) Google Scholar Finally, given the limited availability of ophthalmologists in India, especially in rural areas, along with the continued advancement of the hand-held fundus camera, there is a need for conducting operation research in line with principles of primary health care, which involve choosing the appropriate device, intersectoral coordination, and community participation. These strategies might potentially help to reduce health inequities. I declare no competing interests. National prevalence of vision impairment and blindness and associated risk factors in adults aged 40 years and older with known or undiagnosed diabetes: results from the SMART-India cross-sectional studyBased on the estimated 101 million people with diabetes in 2021 and the interpretation of the data from this study, approximately 21 million people with diabetes have vision impairment in India, of whom 2·4 million are blind. Higher prevalence is observed in those from lower socio-economic strata and policy makers should focus on these groups to reduce inequalities in health care. Full-Text PDF Open Access