GSTM1 and diabetes mellitus: We also included general patient data consisted of age, sex, body mass index (BMI), place of residence, educational level, diabetes mellitus status, and duration of HD; as well as clinical indicators comprised of Ca, P, serum albumin(ALB), Hemoglobin(Hb), PTH, serum creatinine(sCR), serum urea nitrogen (BUN), urea nitrogen clearance index (KT/V), ferritin (FER) before dialysis, and hs-CRP to analyze the determinants of Itching in these patients.