- Purpose The objective of the study was to assess the influence of socioeconomic status (SES) on the care of patients with diabetes. Methods Quality indicators for patients who were taking medication for diabetes were established. Overall compliance with the quality indicators, as well as prevalence of diabetes by age, were obtained from a national database. Patients with national tax exemptions (used as a marker for low SES) were compared to those without. Results Of 4,110,852 citizens aged 18–74, 210,988 (5.1%) were receiving medication for diabetes. The prevalence of diabetes reached 19.9% in people aged 65–74. 495,392 citizens had an exemption, and they had a higher prevalence of diabetes that those who did not (15.4% vs. 3.7%). Patients with an exemption had a higher rate of having a yearly HbA1c done, a yearly LDL level done, a yearly eye exam, a yearly urinary protein exam, of being treated with insulin for an elevated HbA1c than those without an exemption. In patients with an exemption there was a lower percentage with an HbA1c less than 7%, a higher percentage with an HbA1c greater than 9%, and a lower percentage with an LDL less than 130. Multivariate analysis showed that exemption status was a predictor of better performance on process measures (LDL test done, OR-1.03, 95% CI 1.01–1.06, HbA1c test done, OR 1.03, 95% CI- 1.01–1.05) and of worse outcomes (high LDL, OR 0.92, 95% CI, 0.90–0.95 and high HbA1c, OR, 0.85, 95% CI, 0.83–0.87). Conclusions In a country with universal healthcare, patients from a lower SES had an increased prevalence of diabetes and had greater adherence to preventive healthcare measures However, they were less successful in meeting target treatment goals.