Diabetes Mellitus (DM) is a metabolic disease that is increasing significantly every year in Indonesia. This disease requires medical maintenance on an ongoing basis to prevent further complication. The purpose of this study was to determine the usage pattern of insulin, the percentage incidence of side effect of insulin and identification of the side effect of insulin by Naranjo algorithm. This research was a descriptive study and conducted by collecting data with cross-sectional prospective study design in hospitalized patients with DM type 2 at RSUP Dr. Sardjito Yogyakarta. Data were collected by medical record and interview using Naranjo algorithm. The total subjects from this study are 27 people.  The results showed that Aspart insulin (66,67%) and Aspart + protaminated insulin aspart (30% : 70%) (33,33%) were used by patients DM type 2. Percentages of the side effect of Aspart insulin was 68,42% and Aspart insulin + protaminated aspart insulin (30% : 70%) was 31,58%. The incidence of adverse effect in the use of Aspart insulin was dizziness (47,37%) with possible scoring from Naranjo algorithm. The incidence of adverse effect in the use of Aspart insulin + protaminated insulin Aspart (30% : 70%) were weakness (50%) and dizziness (50%) with possible scoring from Naranjo algorithm.  
Keywords : The Side Effect of Insulin, Diabetes Mellitus Type 2, Naranjo Algorithm.