Background: Health professionals assign diabetes patients "homework" in that they give them instructions on how to manage diabetes, recognizing that most diabetes care takes place in the home setting. We studied how homework is practiced and whether knowledge and behavioral practices related to diabetes self-management diffuse from patients to their housemates. Method: This mixed-methods study combined quantitative data from a household survey including 90 rural Ugandan households (50% had a member with type 2 diabetes [T2D]) with qualitative data from health facilities and interviews with 10 patients with T2D. Focus for data collection was knowledge and practices related to diabetes homework. A generalized mixed model was used to analyze quantitative data, while content analysis was used for qualitative data analysis. Results: Patients with T2D generally understood the diabetes homework assignments given by health professionals and carried out their homework with support from housemates. Although adherence to recommended diet was variable, housemates were likely to eat a healthier diet than if no patient with T2D lived in the household. Knowledge related to diabetes homework diffused from the patients to housemates and beyond to neighbors and family living elsewhere. Knowledge about primary prevention of T2D was almost absent among health staff, patients, and relatives. Conclusions: Homework practices related to T2D improve diabetes-related knowledge and may facilitate healthy eating in nondiabetic housemates. These findings suggest that having a chronic disease in the household provides an opportunity to improve health in the entire household and address the lack of knowledge about prevention of T2D.