Nicotinamide (a form of vitamin B3) has been investigated for its potential role in supporting or treating diabetic retinopathy, but the evidence is limited and primarily preclinical. Diabetic retinopathy is a complication of diabetes characterized by damage to the retinal blood vessels, often driven by hyperglycemia-induced oxidative stress, inflammation, and vascular dysfunction. Nicotinamide has demonstrated antioxidant and anti-inflammatory properties, and it plays a crucial role in cellular energy metabolism by serving as a precursor to NAD⁺, a molecule important for cellular repair and mitochondrial function.

Several animal studies and cell-based experiments suggest that nicotinamide may protect retinal cells from hyperglycemia-induced damage, reduce oxidative stress, and inhibit pathways involved in vascular leakage and inflammation. However, robust clinical trials in humans are lacking. Some early-stage clinical research indicates that supplementation may have beneficial effects on retinal health in diabetes, but these studies are generally small, not well-controlled, or preliminary.

Major diabetes and ophthalmology guidelines do not currently recommend nicotinamide as a treatment for diabetic retinopathy due to the insufficient clinical evidence. Its use is based more on encouraging mechanistic data rather than clear, validated patient benefit. In summary, while there is a scientific rationale and some supportive data from basic research, the clinical evidence supporting the use of nicotinamide in diabetic retinopathy is weak and not yet established.