Introduction: Diabetes mellitus (DM) is a chronic disease with high prevalence in the world and Iran. Uncontrolled DM puts financial pressure on health system and society. It also affects patients physically and mentally, and changes their social relationship with others. In spite of advances in DM control, there is only a little information regarding patients’ experience of living with DM and coping with this disease in Iran. This study aimed to explore diabetic patients’ experience of coping with DM. Method: This qualitative study was conducted using grounded theory and semi-structured interviews in Yazd, Iran, in 2013. Fifteen diabetic patients (8 females and 7 males) were selected using purposive sampling. Recorded interviews were transcribed verbatim and analyzed using Strauss and Corbin method simultaneous with data collection. Guba and Lincoln criteria were used to ensure credibility of the findings. Results: In this study, 73 primary codes, 22 primary categories, and 7 main categories for strategies of coping with DM were extracted. The categories include: perceived problem, trust in treatment recommendations, ability to predict prognosis, subjective theory, family support, comorbidities and life events. According to diabetic patients’ experience of living with DM, these factors have a key role in coping with diabetes. Conclusion: According to the results, the coping strategy of diabetic patients is a correlated, dynamic, complex, and constant concept influenced by the factors affecting diabetic patients and the disease. On the one hand, trust in treatment recommendations and ability to predict prognosis, and on the other hand, life events and family support affect coping strategies for diabetes. The findings of this study can help health policy makers to introduce interventions and educational programs to improve DM control.