Background: Diabetic retinopathy (DR) is a leading cause of preventable blindness, with macular involvement being the primary determinant of visual impairment. Optical coherence tomography (OCT) provides an objective, non-invasive method for evaluating central macular thickness (CMT) and detecting early macular changes. Aim: To assess changes in central macular thickness in diabetics with different stages of diabetic retinopathy using optical coherence tomography. Materials and Methods: This cross-sectional observational study was conducted over a period of 18 months. A total of 114 patients were evaluated. Comprehensive ophthalmic examination, best-corrected visual acuity (BCVA), fundus evaluation, and OCT-based CMT measurement were performed. Diabetic retinopathy was staged as mild, moderate, severe non-proliferative diabetic retinopathy (NPDR) and proliferative diabetic retinopathy (PDR). Statistical analysis included one-way ANOVA and chi-square tests. Results: The mean CMT showed a progressive increase with severity of diabetic retinopathy: mild NPDR (240.2 ± 20.2 µm), moderate NPDR (277.2 ± 8.8 µm), severe NPDR (308.7 ± 5.9 µm), and PDR (308.8 ± 19.4 µm), which was statistically significant (p < 0.001). Diabetic macular edema was significantly associated with advanced stages of DR (p < 0.001). Higher CMT values were observed with increasing age, poor glycemic control, and male gender. Conclusion: Central macular thickness increases significantly with advancing stages of diabetic retinopathy. OCT-measured CMT is a reliable and objective parameter for early detection and assessment of macular involvement, facilitating timely intervention and prevention of vision loss.