BACKGROUND: Chronic disease significantly influences mental health, identity, and self-esteem. It is deeply interconnected with loneliness, frailty, stress, mental health, and the ageing process, forming a complex and interrelated dynamic. The aim was to find an association between loneliness, frailty, mental health, and the patient's self-management. METHODS: A cross-sectional study was conducted between October 2023 and May 2024. A total of 605 patients with chronic disease took part in the research, of whom 67% were female and 33% were male. In total, 71% of participating patients lived in a home environment, and 19% lived in retirement homes. RESULTS: 605 respondents with chronic disease participated in the study and were recruited using a purposive sampling method. Participants were drawn from healthcare settings, including primary care centres, outpatient clinics, and nursing homes, to increase representativeness. The study achieved a response rate of 55% after distributing 1100 questionnaires. Data were analysed with SPSS Statistics 25.0 using descriptive and inferential statistical methods, including non-parametric tests (Kruskal-Wallis test, Mann-Whitney U test) and Spearman's correlation. The main results showed that patients who self-rated their chronic disease as well- or very well-managed (81%) were less frail ( CONCLUSIONS: Without adequate assessment and support from the healthcare system, patients may face challenges in meeting their needs, which can contribute to loneliness, frailty, and mental health decline. It is crucial to acknowledge that every individual with a chronic disease, regardless of age, education level, or condition, must actively participate in managing their chronic disease. Recognising the importance of self-management and its impact on mental health is essential to mitigating the negative effects of chronic disease on a patient's quality of life.