Correlation of Diabetic Retinopathy Severity with Glycated Hemoglobin (HbA1c) and Duration of Diabetes Mellitus

Background: Diabetic retinopathy (DR) is a major microvascular complication of diabetes mellitus. Glycated hemoglobin (HbA1c) reflects chronic glycaemic exposure, while duration of diabetes represents cumulative disease exposure. Both are clinically relevant to the burden and severity of DR. the aim is to determine the association of DR severity with HbA1c level and duration of diabetes mellitus in patients with type 2 diabetes mellitus. Material and Methods: This hospital-based cross-sectional analytical study included 100 adults with type 2 diabetes mellitus who underwent ophthalmic evaluation and HbA1c estimation. DR was graded according to the International Clinical Diabetic Retinopathy Disease Severity Scale. HbA1c and duration of diabetes were analysed as continuous variables and in predefined categories. Spearman rank correlation was used for ordinal DR severity, while one-way ANOVA and Kruskal–Wallis tests were used to compare continuous variables across DR severity groups. Categorical associations were assessed using chi-square or Fisher’s exact tests, as appropriate. Statistical significance was set at p<0.05. Results: Of 100 participants, 54 (54.0%) were male and 46 (46.0%) female. DR severity was: no DR 28 (28.0%), mild NPDR 26 (26.0%), moderate NPDR 22 (22.0%), severe NPDR 14 (14.0%), and PDR 10 (10.0%). Mean HbA1c increased progressively across severity categories, with group means of 6.74±0.42%, 7.28±0.51%, 8.31±0.56%, 9.07±0.73%, and 9.87±0.78%, respectively. Mean diabetes duration increased from 6.03±5.39 years in patients without DR to 17.82±3.56 years in PDR, though a small subset of long-duration patients retained mild or absent retinopathy. HbA1c showed a strong positive Spearman correlation with DR severity (ρ=0.885, p<0.001); diabetes duration showed a more moderate, though still significant, positive correlation (ρ=0.549, p<0.001). One-way ANOVA was significant for HbA1c (F=85.21, p<0.001) and diabetes duration (F=13.88, p<0.001). Kruskal–Wallis tests confirmed significant between-group differences for HbA1c (H=78.36, p<0.001) and duration (H=33.78, p<0.001). Conclusion: In this hospital-based sample, higher HbA1c and longer duration of diabetes were strongly associated with increasing DR severity. The findings support attention to sustained glycaemic control and regular retinal screening. Because of the cross-sectional design, these associations should not be interpreted as proof of causation or temporal progression.

Keywords: Diabetes mellitus, diabetic retinopathy, HbA1c, glycated hemoglobin, duration of diabetes, NPDR, proliferative diabetic retinopathy.