The Diabetes Mellitus is a chronic disease whose treatment requires strict clinical care and continuing education such as medication, nutrition and physical activity. Education is a decisive factor in preventing complications that may arise from the failure of therapy. Therefore, the therapeutic adherence must include a psycho-social approach.

To study the degree of adherence to the pharmacologic treatment and dietary habits in patients with type I and type II diabetes mellitus and to evaluate the influence of the level of education, sex and type of diabetes.

A cross-sectional study was conducted of the descriptive-correlational type. The sample consisted of 100 diabetic type I and type II individuals and was obtained by convenience at the health center of S. Martinho do Bispo, in Coimbra - Portugal, during the period from May till June 2009.

The results indicate a high adherence to therapy, reflected trhough the diet and also the pharmacological treatment. However, the higher adherence found was related to prescription of medication. The demographic variables such as sex and level of education of patients, seem to positively influence the adherence to treatment.