The purpose of this study was to examine self-care behaviors of adults with type 2 diabetes mellitus living in the Metropolitan Area of Thessaloniki in Northern Greece. The Summary of Diabetes Self-Care behaviors measurement was administered to 215 patients, out of which 177 were eligible to participate (87 males). Patients, aged 30 years or more, were recruited through a university hospital day-clinic. Older patients (>65 years), as well as those with "higher educational level" did not distribute their daily carbohydrate intake equally. Nevertheless, they were more likely to adapt to their physician's recommendations regarding medication and to regularly perform suggested blood glucose checking. Exercise patterns were more often found for higher educated, earlier diagnosed males. Younger patients were less likely to follow their healthcare professional's recommendations, regarding diet, medication intake, blood glucose checking, foot care and exercise compared to older patients. These results pose a higher risk for complications and morbidity in younger patients with type 2 diabetes mellitus, who most possibly will require intensive treatment in the future.