Complications are the factors that determine the length of the day of treatment of diabetes mellitus patients in the hospital such as hypertension, stroke, coronary heart disease, cholesterol, obesity and others. This study aims to analyze differences in Length of Stay (LOS) of patients with diabetes mellitus based on complications in RSUP Dr. Sardjito Yogyakarta.This research is an analytic observational quantitative research with cross sectional design. The population is all people with diabetes mellitus from year 2011-2016 recorded in electronic medical record. All the population used as research sample that is as many as 1,554 people. Independent variables in this study were hypertension, nephropathy, neuropathy, obesity, CHD, stroke, and pulmonary TB. Dependent variable is Length of Stay or long treatment of diabetes mellitus patient. Data analysis was performed using Independent T test. Diabetes mellitus patients at RSUP Dr. Sardjito year 2011-2016 amounted to 1,554 people with a trend that tends to decline. Most patients were aged 56-63 years (27.86%). The incidence of diabetes mellitus is dominated by type 2 with the highest complications being hypertension, nephropathy, and neuropathy. Based on the result of statistical test, there is a significant difference between the average LOS between patients with diabetes mellitus who have hypertension complications with non-hypertensive (p-value = 0.00), neuropathy with non-neuropathy (p-value = 0.00), coronary heart disease with which is not coronary heart disease (p-value = 0.035), and stroke with non-stroke (p-value = 0.032). Conclusions: There is significant difference in mean LOS among patients with diabetes mellitus who have complications of hypertension, neuropathy, coronary heart disease, and stroke with no complications of the disease.