The objective is to review the most common causes of vision loss in patients with diabetes with the goal of better managing patients with diabetic eye disease. In this review, the causes of vision loss, and the clinical evaluation and management of diabetic retinopathy (DR) and diabetic macular edema (DME) are outlined. Patients with diabetes mellitus have an increased risk of vision loss and blindness. In patients with diabetes, the primary mechanism responsible for vision loss is centrally involved DME or clinically significant macular edema (CSME), defined as vascular leakage resulting in fluid accumulation that affects the center of the macula. DR and DME are thought to result from the effects of excessive blood glucose on the vessels that produces microvascular damage. The progression of DR can be slowed by intensive glycemic and blood pressure control. Severe visual loss from proliferative DR and moderate visual loss from DME can be reduced by laser photocoagulation. DR and DME are diagnosed on dilated retinal examination and confirmed with diagnostic testing. Many experts and associations recommend that patients with diabetes have an yearly, thorough, dilated eye exam. This manuscript describes the case history of a patient with diabetes and vision loss.