After being diagnosed with diabetes, cats can live a quality life for several years with proper management and care. The life expectancy varies depending on factors such as the cat's overall health, age at diagnosis, and how well the diabetes is managed through diet, exercise, and insulin therapy if required. On average, with diligent care, diabetic cats can live as long as non-diabetic cats. However, they typically require more frequent veterinary check-ups to monitor their condition and adjust treatment as necessary. Early detection and consistent management are crucial to maximizing their lifespan.