Diabetes may cause cataracts. Diabetes mellitus is a group of metabolic diseases characterized by chronic hyperglycemia due to multiple etiologies and caused by defective insulin secretion and/or utilization. Diabetes mellitus is one of the causes of cataracts, and in addition to cataracts, diabetes mellitus may lead to diabetic retinopathy, glaucoma, refractive changes, and iridocyclopathy. In addition to diabetes, epidemiologic studies have shown that ultraviolet radiation, hypertension, cardiovascular disease, organic trauma, excessive alcohol consumption and smoking are associated with cataract formation. It is recommended that patients with diabetes mellitus with cataracts go to regular hospitals for timely consultation and treatment.