The purpose of this study was to assess adherence to vascular protection drugs in diabetic patients using a cohort of diabetic patients aged >or=30 years, covered by the public drug insurance in the province of Quebec, excluding gestational diabetes and patients who were hopitalized or died during the 1-year follow-up. Drug adherence was measured using the medication possession ratio. Multivariate analyses, including logit and multinomial logit were used. Of the 170,381 diabetics (mean age: 62 +/- 14 years), 18% and 32% were regular users of ASA and ACEIs/ARBs, respectively. Regular use increased with age (p<0.0001) and comorbidities (p<0.0001). Rural inhabitants were more likely to use ACEIs/ARBs (OR: 1.29; 95% CI: 1.26-1.32) and to be regular users (OR: 1.36; 95% CI: 1.32-1.39). Similar results were found for ASA. In conclusion, despite the high cardiovascular risks associated with diabetes, less than one-third of diabetic adults took vascular-protection drugs regularly. This important issue needs proper attention.