Background: Diabetes is an important health issue, causing most of the other co-morbidities resulting in the high morbidity and mortality burden of any country. Diabetic patients need to engage in regular self-care behaviors with positive coping strategies to enjoy a better quality of life. Objective: To study the moderating role of coping mechanism between physical self-care and quality of life among diabetic patients. Study type, settings & duration: Across-sectional study was conducted at different hospitals in the Lahore district from November 2020 to March 2021.Methodology:The present study recruited a sample of(N= 300) adults from different hospitals of Lahore using G*Power12software, which indicated that for a moderation analysis, a small to medium effect size can reliably be detected in a sample of 284 individuals with 95% level of significance and a 95% power of the test. However, a larger sample of 300diabetic adults was enrolled. The sample had equal representation of both men and women with anage of ≥ 30years(M=33.24years,SD=5.78years). The data was collected from November 2020 to March 2021.The study sample was from the diagnosed patients of diabetes; they were aware of their chronic illness and were taking medicine sregularly. There ported ailment was verified from their medical record. The Self-Care Inventory Scale, the Glucoco per Scale, and the Quality of Life Scale were used to measure physical self-care, coping mechanism, and quality of life respectively. Results: The data was analyzed through IBM SPSS. Findings of the Pearson correlation analysis showed the significant positive relationship of physical self-care with coping mechanism (r = .55, p= .001) and quality of life (r = .43, p= .001); results also highlighted that coping mechanism was positively related to quality of life (r = .37, p= .01). Results of the moderation analysis showed that the coping mechanism strengthened the positive relationship between physical/ self-care and quality of life (B =.18, p< .001, R2=.28) in diabetic patients. Conclusion: Diabetic patients who are involved in physical self-care enjoyed a better quality of life and their quality of life much more improved if these diabetic patients adopted some coping mechanism. Coping mechanism strengthened the positive relationship of physical self-care and quality of life of diabetic patients.