European Journal of Cardiovascular Medicine

India is witnessing a rapid increase in diabetes prevalence, and projections indicate that by 2030, nearly 80 million individuals in the country may be living with the disease [1]. Diabetic retinopathy (DR) has emerged as a major cause of blindness, and its control has been recognized as a priority under the Vision 2020: Right to Sight initiative. A significant challenge is the limited awareness of DR among both patients and healthcare providers, which contributes to late detection and advanced disease presentation [2].

Economic barriers also limit access to essential treatments, such as laser therapy and intravitreal injections, resulting in many patients progressing to

irreversible stages of DR. Clinically significant macular edema (CSME) remains a leading cause of moderate visual loss in diabetes and, if untreated, may lead to long-term disability. In addition, many affected individuals also suffer from comorbidities such as hypertension, dyslipidemia, and diabetic kidney disease. When poorly managed, these conditions can accelerate the progression of retinopathy, underscoring the importance of comprehensive screening and systemic disease control [3]. In India, the reported prevalence of diabetic retinopathy among individuals with diabetes has been estimated to range between 17.6% and 28.2% [4,5]. With improvements in healthcare leading to longer life expectancy among people with diabetes, the overall burden and severity of retinopathy are also expected to rise, posing a significant public health challenge. In resource-limited regions, the problem is further compounded by the high frequency of anemia, which has been identified as a factor that may aggravate the progression of diabetic retinopathy. Diabetic retinopathy often begins without noticeable symptoms. As the disease advances, patients may perceive floaters, distorted or blurred vision, which in severe cases can lead to permanent damage. Hemoglobin A1c (HbA1c) is formed by the non-enzymatic attachment of glucose to hemoglobin, and is widely used as an indicator of long-term glycemic control in individuals with diabetes. Prior research has demonstrated that higher HbA1c levels are associated with increased severity of diabetic retinopathy [6,7].

A longer duration of diabetes, hypertension, and elevated glycosylated hemoglobin, have been identified as consistent risk factors [8]. One study reported that the likelihood of developing proliferative diabetic retinopathy was most strongly influenced by the duration of diabetes and by male sex. Insulin treatment and hypertension were also significant contributors, whereas smoking and HbA1c levels did not show additional independent risk in that population [9].

One investigation found that public awareness and understanding of diabetic retinopathy were generally poor, although individuals with higher literacy levels tended to be better informed. Strengthening educational initiatives is therefore crucial to lessen the burden of vision loss attributable to diabetes. Diabetic retinopathy represents the most common micro vascular complication of diabetes and remains a leading cause of preventable blindness among adults of working age [10]. With the anticipated increase in the number of individuals living with diabetes, demand for ophthalmic services is projected to rise, posing significant challenges for eye-care systems. It is therefore crucial to design and implement screening strategies that are both effective and feasible within the limits of existing ophthalmic infrastructure [11]. When diabetic retinopathy is not monitored or treated for extended periods, it can progress to irreversible and often profound vision loss. Regular eye examinations and early therapeutic intervention are therefore critical in preserving visual function among individuals with diabetes [12]. Promoting awareness of the need for regular eye examinations is a key strategy in the prevention and effective management of diabetic retinopathy [13]. Enhancing patients’ understanding of diabetic retinopathy can promote positive attitudes toward early eye screening and encourage consistent follow-up with diabetes care providers. Such awareness contributes to better management of diabetes and its ocular co morbidities, ultimately helping to reduce the risk of vision loss related to diabetic retinopathy [14]. Awareness about diabetic retinopathy and other diabetes related visual complications as reported by different community-based studies in India varied in the range from 16.1% to 71.3% [15-17].  This suggests that, there exists a lot of difference in the level of awareness regarding diabetic retinopathy among people residing in different areas of the country.

Till date, there stays a lack of studies assessing individual awareness and knowledge about diabetes related ocular complications in this part of southern India. Accordingly, this study was intended to survey the awareness about diabetes mellitus and diabetic retinopathy among patients with diabetes. There are very few studies in the literature have shown the correlation between HbA1c and different grades of diabetic retinopathy.

This was a hospital-based cross sectional study. The study participants were diabetes mellitus patients attending eye OPD and NCD clinic at GIMS Kalaburagi. Institutional Ethics committee permission was taken before the conduct of the study. The IEC approval number is - GIMS/KLB/PHARMA/IEC/210/2023-24. Study duration: 12 Months (November 2023 to November 2024). Inclusion criteria: 1. Diabetic mellitus patients attending GIMS Kalaburagi, Ophthalmology OPD and NCD clinic who were more than 18 years. 2. Willingness to participate in the study were included in the study. Exclusion Criteria: 1. Participants having visually disabling cataract or corneal opacity. 2. Patients with gestational diabetes mellitus. 3. Participants having a previously known cognitive impairment that would affect their ability to complete the survey or follow directions. 4. Participants not giving consent were excluded in the study. Sample size was determined by applying the formula, n=Z2pq/d2, where ‘p’ is the prevalence. From previous study, the prevalence of diabetic retinopathy among Type 2 diabetic patients in a tertiary care hospital in India is presently 16% [18]. So, p=0.16; q= (1-p) i.e., 0.84 and d = allowable error (5% in this study) =0.05. The sample size (n) calculated was 206. A total of 206 patients were included in the present study. Our calculated sample size and sampling method was done in accordance with previous studies done by Anjali P. Shrote al [19], Lokesh S et al [20]. and Rajarshi AS et al [21] Semi-structured, pre-validated, questionnaire was used for data collection as a research tool. A structured questionnaire was designed after minor modifications from previous studies [22]. The questionnaire was filled separately by each participant. The questionnaire was inclusive of ten questions related to knowledge about the effect of diabetes on the eyes, and other aspects and their responses were recorded. Methods of collection of the data, details of study protocol were explained to the patients in his/her own language and informed consent was taken. All patients underwent comprehensive eye examination, retinal evaluation were done using 90 D lens on slit lamp and indirect ophthalmoscope. Diagnosis of diabetic retinopathy was based on Early Treatment Diabetic Retinopathy (ETDRS) classification [8]. The mean HbA1c levels were compared with NPDR mild, moderate, severe, very severe and PDR into early PDR and high-risk PDR groups according to ETDRS Classification. Blood investigations -Hemoglobin, fasting blood, random blood sugar, Glycosylated haemoglobin (HbA1c levels) were sought. The blood sample (5ml) was withdrawn from all subjects by vein puncture. 2ml of the blood was placed in EDTA tubes and stored at (2-8 c) for HbA1c measurement. The remaining 3 ml of the blood was placed in plane tubes. The blood samples were centrifuged (at 3000 rpm for 10 minutes). The serum was isolated and stored at 2 to 8 degrees Celsius and analyzed for Hemoglobin, fasting blood, random blood sugar levels. Determination of random blood glucose levels and HbA1c- was done by Automatic Biochemistry Analyzer. Statistical analysis: Data was collected, compiled and tabulated in Microsoft Excel sheet. The statistical analysis was performed using Jamovi 2.5 version statistical tool. The Quantitative data was analyzed in percentages and proportions. The t- student test was applied. Pearson’s correlation regression test was applied. The p-value of <0.05 was considered as statistically significant.

[Table/Fig-1]: Showing the age distribution among study participants.

In our study, In table 1, majority of patients were  in the age group of 50-60 years accounting for 38.34% followed by in age group of 60-70 years, <50 years and >70 years accounting for 29.62%, 18.44% and 13.60% respectively.

[Table/Fig-2]: Showing the gender distribution among study participants.

In table 2, Among 206 patients with diabetes mellitus patients 109 (52.92%) are males and 97(47.08%) are females. In this study prevalence of diabetic retinopathy is 64.5% (133 patients).

[Table/Fig-3]: Showing the percentage of diabetic retinopathy based on grading:

In table 3, all patients with diabetic retinopathy were classified according to the ETDRS grading system. Among the 133 affected individuals, 53 (25.8%) had mild NPDR, 32 (16.5%) had moderate NPDR, 4 (1.9%) had severe NPDR, 6 (2.9%) had very severe NPDR, 8 (3.9%) had proliferative diabetic retinopathy (PDR), and 8 (3.9%) were diagnosed with advanced diabetic eye disease. In addition, 22 (10.7%) patients presented with clinically significant macular edema (CSME). A further 64 subjects showed no evidence of diabetic retinopathy.

[Table/Fig-4]: Showing the correlation of severity of diabetic retinopathy with HbA1c level:

Table 4, it was observed that, in the study population, 38 patients were identified with mild NPDR, and 5 patients with moderate NPDR had HbA1c values below 8.0%. Among those with HbA1c levels between 8.0% and 10.0%, there were 9 without retinopathy, 15 with mild NPDR, 24 with moderate NPDR, 2 with very severe NPDR, 2 with advanced diabetic eye disease, and 4 with clinically significant macular edema (CSME). Patients with HbA1c levels greater than 10.0% included 3 with moderate NPDR, 4 with severe NPDR, 4 with very severe NPDR, 8 with proliferative diabetic retinopathy (PDR), 6 with advanced diabetic eye disease, and 18 with CSME. A statistically significant positive correlation was observed between HbA1c levels and the severity of diabetic retinopathy (r = 0.523, 0.687, and 0.872 for increasing grades; p < 0.05). These findings indicate that higher stages of diabetic retinopathy are strongly associated with elevated HbA1c levels.

[Table/Fig-5]: Showing the distribution of awareness of diabetic retinopathy:

From, table 6, it was evident that, among the participants 42(20.38%) males and 25(12.14%) females are aware of diabetic retinopathy, 67(32.52%) males and 72(34.96%) females are unaware of diabetic retinopathy.

[Table/Fig-6]: Showing the Systemic risk factors associated with diabetic retinopathy:

From table 6, it is evident that, among 133 diabetic retinopathy patients, 58 patients had systemic risk factor contributing to severity of disease. 36 (27.06%) patients had hypertension, 12(9.02%) had dyslipidemia, 8(6.01%) had anemia and had chronic kidney disease.

In this study, from table 1, it is evident that majority of patients were in the age group of 50-60 years accounting for 38.34 %.  From table 2, it was observed that gender distribution showing, increased incidence of diabetic retinopathy in male compared to females. This result is similar to Lokesh S et al [20], and Nivedita H et al [23].  From  table-3 and 4, we found that patient with higher grade of diabetic retinopathy are having increased serum level of HBA1c thus implicating high correlation between serum HBA1c levels and severity of diabetic retinopathy. Positive correlation of diabetic retinopathy was observed with different grades of HbA1c levels (r = 0.523, 0.687, 0.872 respectively) which was statistically significant <0.05. HbA1c level more than 8% are at high-risk of higher grade of diabetic retinopathy. This result is similar to Khalid M et al [24], and Yun et al [25].

The findings of our study are consistent with previous research, as the mean HbA1c level among patients with type 2 diabetes was above 8%, indicating a higher risk of developing vision-threatening forms of retinopathy. Numerous studies have examined the relationship between HbA1c and diabetic retinopathy, and the evidence consistently demonstrates that elevated HbA1c levels are strongly associated with progression and worsening of retinopathy [26]. our study results also confirm this finding.

The present study assessed awareness of diabetic retinopathy among participants. Overall, 28.2% of individuals were aware of the condition, with awareness being higher among males (18.9%) compared to females (9.2%). In contrast, 71.8% of participants had no knowledge of diabetic retinopathy or its potential impact on vision, and this group was more likely to present with advanced grades of retinopathy. Notably, lack of awareness was more pronounced among female participants regarding the ocular consequences of diabetes mellitus.

Hospital-based studies from India have reported awareness of diabetic retinopathy to range between 17.0% and 30.9%[27,28]. In study conducted by Venugopal et al [11]on knowledge of diabetic retinopathy, 34.9% had awareness about the disease. Hypertension as most common co-existing factor occurring with incidence of 30% and 54% in Singh et al [22] and Lokesh et al [20] study respectively. Adele behar et al [29] study showed, examining the association between diabetic retinopathy and hemoglobin levels in individuals with diabetes have concluded that patients with retinopathy tend to have lower hemoglobin values compared to those without retinopathy.

Landmark clinical trials have firmly established the role of glycemic control in the development and progression of diabetic retinopathy. The Diabetes Control and Complications Trial (DCCT) demonstrated a strong association between HbA1c levels and both the onset and worsening of retinopathy [30]. Consistent with these findings, the present study observed a lower frequency of retinopathy among patients with lower HbA1c values, with prevalence increasing progressively at higher HbA1c levels (Table 4). Similarly, the United Kingdom Prospective Diabetes Study (UKPDS) reported that intensive glycemic control using sulfonylureas or insulin significantly reduced the risk of micro vascular complications in individuals with type 2 diabetes [31].

As shown in Table 5, the present study highlights that awareness among patients regarding the impact of diabetes on vision loss remains very limited. It is therefore crucial for healthcare providers to empower patients with knowledge about diabetes, its complications, and the importance of lifestyle modifications such as healthy diet, regular exercise, and weight control. Previous evidence has established that unhealthy lifestyle practices significantly influence HbA1c levels, with dietary habits playing a particularly critical role due to their direct effect on glycemic control. Hence, beyond encouraging physical activity and weight reduction, clinicians should place strong emphasis on promoting balanced dietary practices in line with recommended nutritional guidelines. Patients should be educated on dietary components that directly affect HbA1c levels, while primary care physicians and general practitioners must also be well equipped with this knowledge through Continuing Medical Education (CME) and similar programs. A patient-empowerment approach, complemented by structured diabetes self-management education programs focusing on lifestyle modification, can yield meaningful improvements in both glycemic control and prevention of diabetic retinopathy.

As shown in Table 6, among the 133 patients with diabetic retinopathy in this study, 58 individuals were found to have systemic risk factors contributing to disease severity. Of these, 36 patients (27.06%) had hypertension, 12 (9.02%) had dyslipidemia, 8 (6.01%) presented with anemia, and 2 had chronic kidney disease. Hypertension emerged as the most frequent co-morbidity associated with diabetic retinopathy in this cohort. Limitations of this study are that it was a single center study with limited number of patients. Multicenter study is suggested to further support relationship of HbA1c levels and severity of diabetic retinopathy.

This study demonstrates a strong positive correlation between HbA1c levels and the severity of diabetic retinopathy, with higher HbA1c values associated with more advanced retinopathy changes. Lack of awareness about the disease was also evident, contributing to delayed presentation and greater visual impairment. As diabetic retinopathy is a preventable cause of blindness, there is an urgent need to enhance public awareness through targeted measures such as educational pamphlets, posters in public spaces, and media campaigns highlighting ocular complications of diabetes. The study further identified systemic co-morbidities—including hypertension, dyslipidemia, and anemia—as important factors associated with the prevalence and severity of diabetic retinopathy. Strengthening patient education, promoting regular health check-ups, and encouraging timely hospital visits in the presence of risk factors are essential strategies to reduce the burden of diabetic retinopathy and its vision-threatening complications. Acknowledgments - Authors acknowledge the Department of Health Research (DHR), New Delhi, India for providing the research funding and facilities at Multi-Disciplinary Research Unit (MRU), Gulbarga Institute of Medical Sciences, Kalaburagi for the research project. Financial support: Multi-Disciplinary Research Unit (MRU), Department of Health Research (DHR), New Delhi, India Conflict of Interest: None.

1. Gadkari SS, Maskati QB, Nayak BK. Prevalence of diabetic retinopathy in India: The All India Ophthalmological Society Diabetic Retinopathy Eye Screening Study 2014. Indian J Ophthalmol. 2016 ;64(1):38-44.

2. Raman R, Ganesan S, Pal SS, Kulothungan V, Sharma T. Prevalence and risk factors for diabetic retinopathy in rural India. Sankara Nethralaya Diabetic Retinopathy Epidemiology and Molecular Genetic Study III (SN-DREAMS III), report no 2. BMJ Open Diabetes Res Care. 2014 ;2(1):e000005.

3. Shah K, Gandhi A, Natarajan S. Diabetic Retinopathy Awareness and Associations with Multiple Comorbidities: Insights from DIAMOND Study. Indian J Endocrinol Metab. 2018;22(1):30-35.

4. Das T Aurora,Chhablani J, Giridhar A,Kumar A, Raman R et al. Evidence based review of diabetic macular oedema management. Consensus statement on Indian treatment guidelines. Indian J Ophthalmol 2016; 64:14-25.

5. T. Jayalekshmi, K.P. Poulose. Prevalence of diabetic retinopathy in patients in a tertiary hospital in south India. Int J Med Res Rev 2016;4(10):1802-1806.

6. Zhang R, Li Y, Zhang S, et al. The association of retinopathy and plasma glucose and HbA1c: a validation of diabetes diagnostic criteria in a Chinese population. J Diabetes Res 2016;:4034129:1-7

7. Lind M, Pivodic A, Svensson A, et al. HbA1c level as a risk factor for retinopathy and nephropathy in children and adults with type 1 diabetes: Swedish population based cohort study. BMJ 2019;366:1-9.

8. Solomon SD, Goldberg MF. ETDRS grading of diabetic retinopathy: still the gold standard? Ophthalmic Res. 2019;62:190–5.

9. Magri CJ, Calleja N, Buhagiar G, et al. Factors associated with diabetic nephropathy in subjects with proliferative retinopathy. Int Urol Nephrol. 2012; 44:197–206.

10. Nittala MG, Keane PA, Zhang K, Sadda SR. Risk factors for proliferative diabetic retinopathy in a Latino American population. Retina. 2014; 34(8):1594-9.

11. Venugopal D, Lal B, Fernandes S, Gavde D. Awareness and knowledge of diabetic retinopathy and associated factors in Goa: A hospital-based cross-sectional study. Indian J Ophthalmol. 2020;68(2):383-390.

12. Congdon N, O’Colmain B, Klaver CC, Klein R, Muñoz B, Friedman DS, et al. Causes and prevalence of visual impairment among adults in the United States. Arch Ophthalmol 2004;122:477 85.

13. Liu L, Wu J, Yue S, Geng J, Lian J, Teng W, et al. Incidence density and risk factors of diabetic retinopathy within type 2 diabetes: A five year cohort study in China (report 1). Int J Environ Res Public Health 2015;12:7899 909.

14. Dandona R, Dandona L, John RK, McCarty CA, Rao GN. Awareness of eye diseases in an urban population in Southern India. Bull World Health Organ 2001;79:96 102.

15. Saikumar SJ, Giridhar A, Mahesh G, Elias A, Bhat S. Awareness about eye diseases among diabetic patients: A survey in South India. Community Eye Health 2007;20:16 7.

16. Koshy J, Varghese DL, Mathew T, Kaur G, Thomas S, Bhatti SM. Study on KAP of ocular complications due to diabetes among type II diabetics visiting a tertiary teaching hospital. Indian J Community Health 2012;24:27 31.

17. Gadkari SS, Maskati QB, Nayak BK. Prevalence of diabetic retinopathy in India: The All India Ophthalmological Society Diabetic Retinopathy Eye Screening Study 2014. Indian J Ophthalmol 2016;64:38 44.

18. Rao CR, Kamath VG, Shetty A, Kamath A. A study on the prevalence of type 2 diabetes in coastal Karnataka. Int J Diabetes Dev Ctries. 2010;30(2):80-5.

19. Anjali P. Shrote, Sachin Diagavane. Clinical Evaluation of Correlation Between Diabetic Retinopathy with Modifiable, Non-Modifiable and Other Independent Risk Factors in Tertiary Set-up in Central Rural India. Journal of clinical and diagnostic research. 2015; 9(10): NC10-NC14.

20. Lokesh S, Shivaswamy S. Study of HbA1C levels in patients with type 2 diabetes mellitus in relation to diabetic retinopathy in Indian population. Int J Adv Med. 2018;5(6):1397-1401.

21. Rajarshi AS , Pinaki Das , Sunita Das , Bosumita Sinha. Association of Age and Sex with Different Status of Serum Vitamin D Level among Different Grades of Diabetic Retinopathy: A Cross-sectional Study. Journal of Clinical and Diagnostic Research. 2022;16(4): CC04-CC09.

22.  Singh A, Tripathi A, Kharya P, Agarwal P. Awareness of diabetic retinopathy among diabetes mellitus patients visiting a hospital of North India. J Family Med Prim Care 2022;11:1292-8.

23.Niveditha H, Yogitha C, Liji P, Sundeep Shetty, N.V.V. Himamshu, Vinutha BV, et al.“Clinical correlation of hba1cand diabetic nephropathy with diabetic retinopathy”. Journal of Evolution of Medical and Dental Sciences 2013; 2(49);9430-9435.

24. Khalid M Alabdul wahab, Relationship between Diabetic Retinopathy and HbA1c in Type 2 Diabetics, Kingdom of Saudi Arabia , J Res Med Dent Sci, 2019,7(5): 1-4.

25. Yun WJ. Relationship between glycemic control and diabetic retinopathy.J Korean Geriatrics Society 2010; 14:234-241.

26. Annunziata K, Pomerantz D, Dibonaventura M, et al. PDB71 patient access, HbA1c knowledge, and health outcomes among type 2 diabetes patients in Brazil. Value in Health 2012; 15: A506.

27. Hussain R, Rajesh B, GiridharA, Gopalakrishnan M, Sadasivan S, James J, et al. Knowledge and awareness about diabetes mellitus and diabetic retinopathy in suburban population of a South Indian state and its practice among the patients with diabetes mellitus: A population-based study. Indian J Ophthalmol 2016;64:272-6.

28.Koshy J, Varghese DL, Mathew T, Kaur G, Thomas S, Bhatti SM. Study on KAP of ocular complications due to diabetes among type II diabetics visiting a tertiary teaching hospital. Indian J Community Health 2012;24:27-31.

29. Bahar A, Kashi Z, Ahmadzadeh Amiri A, Nabipour M. Association between diabetic retinopathy and hemoglobin level. Caspian J Intern Med. 2013;4(4):759-62.

30. Diabetes Control and Complications Trial Research Group. The effect of intensive treatment of diabetes on the development and progression of long-term complications in insulin-dependent diabetes mellitus. New England J Med. 1993;329(14):977-86.

31. UK Prospective Diabetes Study (UKPDS) Group. Intensive blood-glucose control with sulphonylureas or insulin compared with conventional treatment and risk of complications in patients with type 2 diabetes (UKPDS 33). Lancet. 1998 ;352(9131):837-53.