Background: Diabetes Mellitus (DM) is a chronic disease of great importance, both for the impact it causes on the health, as the disorders, complications and losses that may originate in quality of life. Objective: Evaluate the impact of type 2 diabetes on quality of life of patients registered in basic health units in Curitiba -PR. Method: Cross-sectional observational study. Sample of 983 patients older than 18 years of both sexes, DM2 patients for over a year, randomly selected and registered in Basic Health Units in Curitiba -PR, between 2010 and 2012. It was used a questionnaire with 14 objective questions about the patient, the disease and the patient's knowledge about it, and another questionnaire, DQOL-Brazil (Diabetes Quality of Life Measures-Brazil), containing 46 questions, divided into four domains (Satisfaction, impact, concern about the disease and vocational / social concern). This research is focused on impact domain, which was divided in physical, emotional and social. Results: The greatest impact on patients' lives was the physical (71,6%), followed by the emotional (77,2%) and the social (81,2%). Patients who use insulin had an average of 71,52%, but those who do not use had an average of 80,06%, a statistically significant difference. Patients with diabetes for over 10 years had an average of 74,59%, while those with less than 10 years had an average of 77,87% with p<0,01.0. Conclusion: DM2 causes a negative impact on quality of life, which is bigger in insulin users and patients with more than 10 years of diagnosis.