T2DM is associated with significant microvascular complications. DR and DME are leading causes of preventable vision loss. Early detection, grading, and identification of systemic risk factors are crucial for timely intervention.

Prevalence varies by population, diabetes duration, glycemic control, and comorbidities. Prospective hospital-based data in [Region/Country] are limited. This study evaluated prevalence, severity, and risk factors of DR and DME among T2DM patients.

MATERIALS AND METHODS

Study Design: Prospective observational study at Pes medical college kuppam. Forty T2DM patients (40-60 years) were enrolled after consent.

Inclusion Criteria: Diagnosed T2DM, age 40-60 year

Exclusion Criteria: Type 1 diabetes, media opacity, prior retinal surgery, other retinal diseases

Ophthalmic Evaluation: BCVA, slit-lamp, IOP, dilated fundus exam, fundus photography. DR graded per ETDRS; DME assessed clinically and by OCT.

Systemic Assessment: Age, sex, duration of diabetes, HbA1c, blood pressure, lipid profile.

Statistical Analysis: SPSS vXX. Categorical variables as numbers/percentages. Associations analyzed with Chi-square/Fisher's exact test. p<0.05 significant.

RESULTS AND DISCUSSION

Mean age: 50 ± 6.2 years; 24 males (60%), 16 females (40%). Duration: 4-8 years. Poor glycemic control (HbA1c>7%) in 16 (40%). Hypertension: 13 (32.5%), dyslipidemia: 10 (25%).

Prevalence: DR: 28 (70%), DME: 11 (27.5%) (Table 1).

Severity: NPDR: 22 (55%), PDR: 6 (15%). Mild NPDR most common (Table 2).

Risk Factors: Poor glycemic control, longer diabetes duration (>6 years), and hypertension significantly associated with DR and DME (p<0.05). Dyslipidemia showed a non-significant trend (Table 3).

Table 1. Prevalence of DR and DME (n=40)

Table 2. Severity of DR (n=28)

Table 3. Association of Risk Factors with DR and DME

*Statistically significant...

DISCUSSION

The high prevalence of DR (70%) and DME (27.5%) reflects hospital-based referral bias. NPDR predominated; PDR in 21.4% indicates delayed presentation.

Poor glycemic control, longer diabetes duration, and hypertension were significant risk factors, aligning with previous studies. Dyslipidemia was non-significant, likely due to small sample size.

Strengths: prospective design, standardized DR grading, systemic risk factor evaluation. Limitations: small sample, single-center design.

Advice on Equations:

1. Sample Size Determination (Prevalence Study)

For estimating prevalence of DR/DME:

Single proportion formula n = Za/2 Z/2P-(1-p) d2

Where:

82

n = required sample size

Za/2 = Z-score for confidence level (1.96 for 95%)

p = anticipated prevalence (from prior studies or pilot data)

d = desired precision (margin of error, e.g., 0.05)

If cluster sampling or hospital-based design: Nadj = n × Design Effect

Single proportion formula n Za/2P-(1-p) d2

Where:

n = required sample size

Za/2 = Z-score for confidence level (1.96 for 95%)

p = anticipated prevalence (from prior studies or pilot data)

d = desired precision (margin of error, e.g., 0.05)

If cluster sampling or hospital-based design:

nadj = n x Design Effect

Add 10-15% for non-response.

2. Prevalence Estimation

Overall prevalence

Severity-specific prevalence

For example, mild NPDR: Prevalence mild NPDR = n mild NPDR/N X 100

Use ETDRS or ICDR classification.

3. Severity Grading (Ordinal Outcome)

DR severity is an ordinal variable:

No DR

Mild NPDR

Moderate NPDR

Severe NPDR

PDR

You may code severity numerically (0-4) only for analysis, not interpretation.

4. Risk Factor Analysis

1. Univariate Analysis

For screening variables:

• Categorical variables:

2 χ² = Σ (Ο-Ε) X E

• Continuous variables:

Student's t-test: t= X1-X2 V

Variables with p < 0.20 typically enter multivariable models.

5. Multivariable Logistic Regression (Binary Outcomes)

Presence of DR (Yes/No)

Presence of DME (Yes/No)

Where:

P = probability of DR or DME

X = risk factors (HbA1c, duration of diabetes, hypertension, BMI, lipids, insulin use, etc.)

Bk = regression coefficients

Adjusted Odds Ratio

AOR = eBk

Report: AOR, 95% Cl, p-value

6. Ordinal Logistic Regression (Severity of DR)

If modeling severity levels:

(P(Y≤) log( P(Y>j) = Aj

Where:

Y = DR severity category

j = cut-point

Proportional odds assumption must be tested

Use multinomial logistic regression if assumption is violated.

7. Continuous Outcomes (Optional - e.g., Central Macular Thickness)

For OCT-based DME analysis:

Y βο + β1Χ1 + β2X2++€

Where:

Y = central macular thickness

€ = error term

8. Model Diagnostics (Important for Publication)

Include:

Hosmer-Lemeshow test for logistic models

Variance Inflation Factor (VIF):

1 VIF 1-R2

AUC = ∫ TPR(FPR) d(FPR)

9. Reporting Standards (Strongly Recommended)

Mention adherence to:

STROBE guidelines

ETDRS / ICDR grading

WHO diabetes definitions

10. Example Methods Statement

Multivariable logistic regression was used to identify independent risk factors for diabetic retinopathy and diabetic macular edema. Variables with p < 0.20 in univariate analysis were entered into the final model. Adjusted odds ratios with 95% confidence intervals were reported. A p-value < 0.05 was considered statistically significant.

Advice on Tables

Table 1. Baseline demographic and clinical characteristics of patients with type 2 diabetes mellitus (n = 40)

Table 2. Prevalence of diabetic retinopathy and diabetic macular edema among patients with type 2 diabetes mellitus (n = 40)

                         Table 3. Severity of diabetic retinopathy among affected patients (n = 28)

Mild non-proliferative diabetic retinopathy was the most common presentation.

Table 4. Distribution of systemic risk factors among patients with and without diabetic retinopathy

 (Descriptive analysis)

Table 5. Systemic risk factors in patients with and without diabetic macular edema

Table 6. Association of systemic risk factors with diabetic retinopathy in patients with type 2 diabetes mellitus

All associations statistically significant (P < 0.05)

Table 7. Association of systemic risk factors with diabetic macular edema

Strong and significant association with DME (P < 0.05)

Hypertension, dyslipidemia, poor glycemic control, and longer duration of diabetes were significantly associated with the presence of diabetic retinopathy (P < 0.05). Diabetic macular edema showed a significant association with hypertension, dyslipidemia, elevated HbA1c levels, and longer duration of diabetes (P < 0.05). Mild non-proliferative diabetic retinopathy was the most common severity grade observed.

Advice on Figures:

1. Flow diagram depicting recruitment and inclusion of patients with type 2 diabetes mellitus.

2. Prevalence of Diabetic Retinopathy and Diabetic Macular Edema

Figure type

✔ Simple vertical bar chart

✔ Black-and-white (print-safe)

✔ No 3D effects, no grid clutter

X-axis

Diabetic Retinopathy

Diabetic Macular Edema

Y-axis

Number of patients (n)

Bar values (place numbers on top of bars)

DR → 28 (70.0%)

DME → 11 (27.5%)

• Prevalence of diabetic retinopathy and diabetic macular edema among patients with type 2 diabetes mellitus (n = 40).
• Diabetic retinopathy was observed in 70% of patients, while diabetic macular edema was present in 27.5% of patients.

3. Severity Distribution of Diabetic Retinopathy

Figure type

✔ Vertical bar chart (severity-wise)

✔ ETDRS-based categories

X-axis

Mild NPDR

Moderate NPDR

Severe NPDR

PDR

Y-axis

Number of patients (n)=40

Bar values

Mild NPDR → 14 (50.0%)

Moderate NPDR → 6 (21.4%)

Severe NPDR → 2 (7.1%)

PDR → 6 (21.4%)

Severity distribution of diabetic retinopathy among affected patients (n = 28).

Mild non-proliferative diabetic retinopathy was the most common severity grade observed.

4. Association of risk factors with DR (P < 0.05)

Figure type

✔ Grouped bar chart

✔ Side-by-side bars

Variables

Hypertension

Dyslipidemia

HbA1c

Statistical annotation above significant bars P < 0.05

Association of systemic risk factors with diabetic retinopathy. Hypertension, dyslipidemia, and poor glycemic control were significantly associated with diabetic retinopathy (P < 0.05).

Figure 5. Association of risk factors with DME (P < 0.05)

Association of systemic risk factors with diabetic macular edema. Hypertension, dyslipidemia, and poor glycemic control showed significant association with diabetic macular edema (P < 0.05).

CONCLUSIONS

DR and DME are common in T2DM. Early screening and strict glycemic and blood pressure control are essential to prevent vision-threatening complications.

Ethics approval and consent to participate

The study was conducted in accordance with the ethical standards of the institutional ethics committee and with the tenets of the Declaration of Helsinki. Ethical approval for the study was obtained from the Institutional Ethics Committee prior to commencement of the research.

All participants were informed in detail about the nature and purpose of the study, the risk factors involved, risk factors, potential benefits. Written informed consent was obtained from each participant before inclusion in the study. Confidentiality of patient data was strictly maintained throughout the study.

 J List of abbreviations

Abbreviation                       Full Form

DR                            Diabetic Retinopathy

DME                      Diabetic Macular Edema

T2DM                  Type 2 Diabetes Mellitus

OCT             Optical Coherence Tomography

BCVA           Best-Corrected Visual Acuity

IOP                        Intraocular Pressure

ETDRS     Early Treatment Diabetic Retinopathy Study

NPDR        Non-Proliferative Diabetic Retinopathy

PDR            Proliferative Diabetic Retinopathy

CST                Central Subfield Thickness

SD                        Standard Deviation

IQR                      Interquartile Range

BMI                     Body Mass Index

HbA1c             Glycated Hemoglobin

Data Availability

The datasets generated and/or analyzed during the current study are available from the corresponding author on reasonable request. Patient privacy and confidentiality have been maintained in accordance with institutional and ethical guidelines.

Conflicts of Interest

There is no conflicts of interest related to this study.

Funding Statement

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

“This study was supported by Pes medical college Kuppam, which provided resources and infrastructure for conducting the research. The funding body had no role in study design, data collection, analysis, or manuscript preparation.”

Authors' contributions

Dr Shaik Salma Begum: Conceptualization, study design, patient recruitment, and manuscript drafting.

Dr. M. Naryan: Interpretation of results, optical coherence tomography imaging, and data analysis.

Dr. G. Hemeswari, Dr. Bollempalli Sri Sai Chaitra, Dr. K. Harshitha, Dr. Rachana.D : Data Collection, Statistical analysis, and figure preparation.

Dr. Joycee : Literature review, manuscript revision, and editing for intellectual content.

All authors: Reviewed and approved the final manuscript and take responsibility for the integrity of the work.

Acknowledgments

We sincerely thank all the patients who participated in this study for their time and cooperation. We are grateful to the staff of the Department of Ophthalmology for their assistance in patient recruitment and data collection. Special thanks to [Department of Ophthalmology Pes kuppam medical college] for support with optical coherence tomography imaging and data management. This study was conducted without any external funding. Finally, we acknowledge the guidance and encouragement of our mentors and colleagues, whose expertise greatly contributed to the completion of this work.

Supplementary Materials

Additional Supplementary materials includes

1.      Case Report Form (CRF) :A structured CRF for data collection, including: Demographics, Diabetes Profile, Ophthalmic Examination, Fundus grading, ETDRS / Modified with DR Severity (ICDR) or No DR / NPDR / PDR

2.      DME status : Absent / CSME / Non-CSME

3.      OCT Thickness and IOP Measurement

4. Study Protocol with Outline of methodology for readers and reviewers.
5. Grading Protocols to Provide standard grading schemes used.
6. Questionnaires or consent forms used in the study.
7. Statistical Analysis Plan (SAP) to describe your intended analysis
8. Ethical Approval & Consent and Ethics Committee approval letter (de-identified)
9. Inter-grader reliability (kappa statistics) for DR grading and other standard grading details.
10. Additional Tables & Figures include:  Prevalence by age categories

   OCT thickness distribution histograms

  Scatter plots of HbA1c vs retinal thickness

  Sensitivity analysis outputs

REFERENCES

1. Tsui et al. 2025 – Prevalence, Incidence & Risk Factors of DR and DME in Early vs Late Onset T2DM – Community-based prospective cohort reporting prevalence and risk associations including HbA1c, duration, and blood pressure.
2. Prevalence of DR & DME in Early- and Late-Onset Diabetes (FS-DIRECT cohort) – Large cohort showing higher DR and DME prevalence in early-onset T2DM with detailed odds ratios.
3. Graue-Hernandez et al. 2020 – DR and DME Prevalence in Recent T2DM – Cross-sectional analysis showing association of duration, HbA1c, hypertension and albuminuria with DR/DME.
4. Yau JW, Rogers SL, Kawasaki R, et al. Global prevalence and major risk factors of diabetic retinopathy. Diabetes Care. 2012;35:556-564.
5. Cheung N, Mitchell P, Wong TY. Diabetic retinopathy. Lancet. 2010;376:124-136.
6. Mohan V, Sandeep S, Deepa R, Shah B, Varghese C. Epidemiology of type 2 diabetes: Indian scenario. Indian J Med Res. 2007;125:217-230.
7. Klein R, Klein BE, Moss SE, Davis MD, DeMets DL. The Wisconsin Epidemiologic Study of Diabetic Retinopathy: XVII. The 14-year incidence and progression of diabetic retinopathy and associated risk factors in type 1 diabetes. Ophthalmology. 1998;105:1801-1815.
8. Early Treatment Diabetic Retinopathy Study Research Group. Grading diabetic retinopathy from stereoscopic color fundus photographs-ETDRS report number 10. Ophthalmology. 1991;98:786-806.
9. Systematic Review of DME Prevalence & Predictors – Meta-analysis highlighting DME prevalence across studies and risk factor influence (duration, HbA1c).
10. Studies Showing DME Prevalence by DR Severity – Reports increase of DME prevalence with DR severity categories (NPDR → PDR)
11. Ophthalmic Epidemiology Reviews (Epidemiology of DR & DME) – Summarizes diagnostic criteria, severity, trends in DR and DME definitions and epidemiology.
12. Indian Epidemiology Data – Reports prevalence ranges of DR and DME in Indian diabetes populations for regional comparison.