Chronic diseases have become the leading cause of death worldwide, a crisis exacerbated by strained medical resources and growing elderly population. Individually, patients often struggle to interpret early signs of deterioration or maintain care plan adherence. In this paper, we introduce VitalDiagnosis, an LLM-driven ecosystem that shifts chronic disease management from passive monitoring to proactive, interactive intervention. By seamlessly integrating continuous data from wearable devices with the interactive capabilities of LLMs, the system simultaneously manages both acute health anomalies and routine care adherence. It investigates triggers through context-aware inquiries, generates provisional insights within a collaborative patient-clinician loop, and provides tailored guidance. This approach aims to shift care from a reactive to a proactive, collaborative paradigm, improving patient outcomes and alleviating healthcare burdens. The demonstration video can be found at https://tinyurl.com/5xa3ka3a.