Aim: This study was conducted to examine the relationship between socio-demographic characteristics, metabolic variables, and treatment adherence in individuals with diabetes. Methods: The study population consisted of individuals who were treated in Balıkesir State Hospital Endocrinology Clinic, and the study sample included 260 individuals with diabetes who met the inclusion criteria and volunteered to participate in the study. The data were collected between November 30, 2015, and September 30, 2016, by using the face-to-face interview method. In the evaluation of the data, the Shapiro Wilk test was used to analyze the normality of the variables, and Mann–Whitney U and Kruskal–Wallis H tests were used to analyze the differences between the groups. In case of significant differences from the Kruskal–Wallis H test, a post hoc multiple comparison test was employed, and Spearman’s correlation coefficient was used for variables that did not show a normal distribution. Results: Of the individuals with diabetes, 79.23% were female, 40.77% were in the 56-65 age group, 95.77% stated that they followed the recommended treatment regularly, and 95.38% reported that they accepted the treatment. It was determined that 93.08% of the individuals followed their blood sugar, 22.69% regularly applied medical nutrition therapy, 28.84% did regular exercise, 23.46% paid attention to their foot care, and 88.08% had received education on diabetes before. The examination of individuals’ metabolic control levels indicated that the mean HbA1c was 8.57 ± 2.11, the mean total cholesterol was 206.55 ± 48.62 mg/dL, the mean systolic/diastolic blood pressure was 129.88 ± 16.31/78.08 ± 14.39, and the mean body mass index was 29.39 ± 5.65 kg/m². There was a statistically significant difference between gender and acceptance of the treatment, age groups and doing regular exercise, education level and doing regular exercise, paying attention to foot care and previous education on diabetes, HbA1c value and doing regular exercise, and BMI value and regular application of medical nutrition therapy. Conclusion: It was found that the majority of the individuals with diabetes accepted the treatment and controlled their blood sugar, but that the majority of them did not pay attention to their medical nutrition, exercise, and foot care. The healthcare team, especially diabetes nurses, has considerable responsibilities in the treatment and care of individuals with diabetes. Since metabolic variables provide clues about treatment adherence in individuals with diabetes, it is important to monitor patients’ metabolic parameters as well as their body mass index. In this context, it is recommended to evaluate the treatment adherence of individuals with diabetes and their needs in this respect.