Objective Develop individual discriminant models using clinical and psychosocial variables for physicians and patients with diabetes based on their perceptions of patient adherence. Methods This was a cross-sectional research design utilizing a discriminant analysis approach. Type 2 patients on treatment for diabetes for at least 2 years prior to research were selected. Clinical data were obtained from patient records, and psychosocial variables were collected by survey instruments filled out by patients. A final sample of 200 patients was recruited. Results We found a positive correlation between patient and physician assessment of patient adherence behaviors. Greater adherence efforts were associated with lower HbA1c. Better quality of the patient-physician relationship was linked to better patient adherence. Increased HbA1c, longer therapy duration and higher BMI described low patient adherence for physicians. Lower HbA1c, female gender and fewer difficulties in marital adjustment characterized high adherence for patients. Dietary self-efficacy as well as emotional and social isolation discriminated mid-level adherers in both models. Conclusion This research confirmed that patients and physicians perceived and judged patients’ adherence behaviors differently. Physicians and patients associated different clinical and psychological factors with low and high adherence. Further research is recommended to clarify how the quality of the physician-patient as well as the patient-spouse relationship affect dietary efficacy and patient adherence. A randomized, controlled clinical trial approach is recommended to establish the effectiveness of interventions aiming to improve dietary self-efficacy on adherence outcomes.