The aims of this study were to assess adherence to oral hypoglycaemic/cardiovascular drugs and determine non-adherence predictors in type 2 diabetes patients. It was designed as a population-based cross-sectional study in which 90 patients from a primary care setting were studied. Pill count and self-report methods were used to measure adherence. Logistic regression analysis was performed to predict factors related to non-adherence. Adequate adherence to all drugs was found in 29 patients (35.4%; 95% confidence interval (CI) 25.0-45.7). Variables associated with non-adherence were HbA1c odds ratio (OR) 2.32 (95% CI: 1.09-4.95), systolic blood pressure OR 1.68 (95% CI: 1.08-2.62), total cholesterol OR 1.34 (95% CI: 1.08-1.66), number of pills OR 1.80 (95% CI: 1.26-2.55) and duration of disease OR 0.44 (CI 95%: 0.24-0.83). In conclusion, one in three patients had adequate adherence. Factors associated with non-adherence were duration of disease, complexity of drug regimen and inadequate control of cardiovascular risk factors.