Diabetes mellitus is the leading cause of end-stage renal disease in Korea. The management of glycemic control in patients undergoing dialysis is challenging due to the complexity of the treatment and the lack of convincing data supporting the benefits of tight glycemic control. When kidney function decreased, glucose homeostasis changed. Increased insulin resistance due to uremia and decreased insulin secretion resulted in hyperglycemia, and decreased counter-regulatory hormone and renal gluconeogenesis led to hypoglycemia. Moreover, glycosylated hemoglobin is affected by various factors in patients undergoing dialysis, so it is difficult to monitor for glycemic control. Decreased kidney function changes the pharmacokinetics of drugs. Some oral hypoglycemic agents are used for patients undergoing dialysis, but the main treatment for glycemic control is insulin. Considering these factors, the management of glycemic control for patients undergoing dialysis is delicate and should be individualized based on the patient's risk profile.