Annually, millions of Americans experience homelessness. Prevalence of Diabetes (DM) is the same among persons experiencing homelessness (PEH) who are mostly minorities compared to the general population. However, 43.9% of PEH with DM have uncontrolled DM compared to 22.8% of domiciled adults from underserved communities. PEH face multiple barriers to therapeutic lifestyle changes (TLCs) that complicate their DM care. Strategies that support DM self-management education and target self-care behaviors and counseling to reinforce adherence and lifestyle changes contribute to better control of chronic diseases. However, these strategies are not available or accessible to the PEH. For patients, educational and behavioral support by continuing patient contact over several months are effective in the management of chronic diseases. For the general and minority populations, mHealth strategies including short messaging service (SMS) texting have been feasible and acceptable, enhanced self-care and adherence, and improved control of chronic disease including DM. Majority of the PEH have access to mobile phones that can receive and send SMS texts. Considering mobility of the PEH, we propose that an mHealth strategy using SMS texting could provide an alternative tool to offer better communication and information management for DM control, improve targeted outreach, facilitate care coordination, explore barriers and activate patient education, support behavior changes, and improve DM self-care. The mHealth strategies for DM have not been tested in the PEH despite the growing evidence of their effectiveness in DM care and the accessibility of mobile phones among PEH. This study will test this strategy and pave the way for its utilization in the health settings where PEH seek care. The study will be implemented in shelter-clinics in New York City (NYC) and in collaboration with a community organization making sustainability of the intervention effects and its scalability feasible. We propose a mixed methods study: Aim 1: To evaluate the efficacy of a 6-month SMS text program for DM management (INT) versus an attention control (CL) on changes in HbA1c and adherence to DM self-care activities, medications, and appointments at 9 months in PEH with uncontrolled DM age ≥ 21 (n=100). H1) The INT group (n=50) will exhibit an average of 1.1 percentage point reduction in HbA1c compared to the CL group (n=50) at 9 months. H2) PEH in the INT will exhibit better self-care activities and adherence to medications and appointments compared to those in the CL group. HbA1c and adherence to self-care activities (SDSCA), medications (PDC & unannounced pill counts), and appointment will be measured at 0,3,6,&9 months in shelter-clinics. Randomization will be at the individual level in the clinics. Aim 2: To assess patients’ and providers’ attitude, acceptability, and experience of a 6-month SMS text strategy for DM management in the PEH with uncontrolled DM in shelter-clinics. We...