Purpose: To identify the reasons for delayed presentation among patients with sight-threatening diabetic retinopathy (STDR) and to assess their knowledge, attitude, and practice (KAP) patterns in the context of diabetes mellitus (DM) and diabetic retinopathy (DR). Methods: Single-center, cross-sectional, questionnaire-based KAP survey. All consecutive cases of STDR who presented to our tertiary eye care facility from August 2023 to July 2023were recruited. The KAP scoring survey tool was incorporated into the questionnaire to help evaluate and represent the patient’s disease. Results: 200 patients with STDR were enrolled in the study. The mean age of patients was 54 ± 9.3 years; 128 patients were between 41 and 60 years; 152 patients had DM for more than 5 years. The STDR changes were more prevalent in patients with an educational qualification of high school or less (n = 168). Sixty patients had been informed regarding the detrimental effect of diabetes on the eyes and were recommended to consult an ophthalmologist by the treating physician. Of these, 28 patients were educated about retinal changes due to diabetes. One hundred patients in our study had good knowledge about DM; 15 patients had good knowledge about DR. For patients not compliant with follow-ups with the treating physician, the use of “home glucometers for self-monitoring/SMBG” (n = 70) was the most prevalent reason. The main reason for poor compliance for undergoing a dilated fundus examination by the ophthalmologist was “Had good vision, so didn’t feel the need” in 180 patients. Conclusion: The absence of visual complaints, lack of knowledge, and failure to undergo a dilated fundus examination in the past were prevalent risk factors in patients presenting with STDR. Knowledge and practice regarding DR were poor among the patients with STDR. The treating physicians and ophthalmologists were the most common sources for patient education.