Diabetes mellitus is one of the main problems that affect the world, where lifestyle changes play an important role in preventing risks due to the disease, so the research objective is to determine the quality of life in patients with diabetes mellitus treated in the outpatient clinic of a hospital in North Lima. Its research objective is to determine the quality of life in patients with diabetes mellitus treated in the outpatient clinic of a hospital in North Lima. It is a quantitative, descriptive, and cross-sectional study, made up of a total of 113 study participants who responded to a survey of sociodemographic aspects and the Diabetes 39 instrument. Its research objective is to determine the quality of life in patients with diabetes mellitus treated in the outpatient clinic of a hospital in North Lima in the results, we can observe that the quality of life in patients with diabetes mellitus treated in Outpatient consultation, 18 (15.9%) of the patients have a low quality of life, 67 (59.3%) have a medium quality of life and 28 (24.8%) have a high quality of life. In conclusion, education in diabetes patients should be prioritized in relation to their self-care since this will allow for a healthy lifestyle.