Background Angiotensin converting enzyme inhibitor (ACEI) and angiotensin receptor blocker (ARB) groups has renoprotection effect and is recommended in patients with diabetes mellitus and hypertension in Indonesia. But which antihypertensive group is better still debated. Aim The study was conducted to determine effectiveness of ACEI or ARB groups in kidney function, morbidity, and  hyperkalemia. Method Prospective cohort study at Dr. RSUPN Ciptomangunkusumo in 123 patients using validated questionnaire, health record data, and laboratory data. Baseline data were followed prospectively for 3 months. Data processing is done descriptively and analytically. Results Patients in the ACEI and ARB groups had the same characteristics, except the duration of Diabetes mellitus (p = 0.004) longer in ARB group and lower eGFR values (p = 0.040) due to application of National Formulary restrictions in Indonesia. After 3 months of observation, there was no change in parameters in the ACEI group except the increase in BMI values ​​(p = 0.046), whereas in the ARB group there were no changes in parameters except for LDL decreases (p = 0.016) and HDL decreases (p = 0.004). There were no differences in the two groups in terms of changes in the value of Urine Albumin Creatinine Ratio (UACR) (p = 0.675), eGFR (p = 0.062), morbidity (p = 0.309), and potassium value (p = 0.166) 3 months. Antihypertensive ARB has a significant increased and maintained eGFR values (p=0.042) (OR=2,370) after controlled by confounding variables man, LDL, triglyceride baseline, systolic blood pressure and fasting blood glucose. ARB also has a significant increased potassium values (p=0,046) (OR=2,339) after controlled by confounding variables ages, delta systolic blood pressure, potassium baseline, and HDL. Conclusion ARB more effective increasing and maintained eGFR values but also worse side effects increasing potassium values ​​after being controlled by confounding variables.