This study is an observational analytic with a hospital retrospective study. The purpose of this study was to determine the difference and the significant difference between real costs and INA-CBG's rates in patients with type 2 diabetes mellitus in the outpatient unit of X Wonosari Hospital.The study subjects who met the inclusion criteria were 62 medical records where the inclusion criteria in this study were patients with ICD 10 E11.8 diagnosis codes who visited the hospital in January 2018 to December 2018. The results of the descriptive statistics of this study show that the average real cost of type 2 diabetes mellitus patients is IDR 233.428,16. The average difference in real costs with the rate of INA-CBG's is IDR - 48.428,16. The conclusion of this study is that the real cost of patients with type 2 diabetes mellitus is greater than the rate of INA-CBG's in the outpatient unit of PKU Muhammadiyah Wonosari Hospital.