Possible risk factors for DN, including sex, age, hypertension (presence, duration, systolic blood pressure, diastolic blood pressure), the duration of DM, FBG, HbA1c, lipid profile (triglyceride, total cholesterol, low density lipoprotein [LDL] cholesterol), blood urea nitrogen (BUN), creatinine, estimated glomerular filtration rate (eGFR), urine albumin-creatinine ratio, history of smoking (ever smoker/current smoker), and presence of DR, proliferative DR (PDR), and clinically significant macular edema (CSME) were evaluated. From the KNHANES V-2, 3 databases, we collected data regarding various factors obtained through direct interviews using standardized questionnaires.