The prevalence of end-stage kidney disease (ESKD) is growing worldwide; the survival of these patients requires renal replacement therapy (RRT, a complex and costly treatment). Over 20% of the patients that start RTT had diabetes. Limited evidence on the effect of comorbidities on the cost of RRT exists. This review summarizes the available evidence on the effect of diabetes mellitus (DM) on the cost of RRT. Electronic databases were searched using key words that combined RRT with DM and cost. References were identified with title, abstract, and full-text screening. The studies included were published in English and presented data on the cost of RRT in ESKD patients with comparison between DM status. Seventeen studies were included in this review. The crude and adjusted cost of care estimates for patients on dialysis was generally higher for DM patients. The cost of care of ESKD patients differed according to various treatment modalities and these differences, mainly driven by inpatient costs. Overall, we found an increased cost of RRT care in patients with DM regardless of the type of treatment. Future analysis of the effects of multiple comorbidities should be considered to better understand the effect of DM on the cost of RRT.