Improvement of the quality of diabetes care is essential for reducing diabetes complications. Nevertheless, compliance with diabetes clinical practice recommendations is inadequate in primary care. The aim of this study was to assess the impact of diabetes education, when directed simultaneously to both diabetes care providers and patients, on the frequency of performance of relevant laboratory tests and improvement of metabolic control. A three-step educational program was applied at 45 community clinics of a health-managed organisation comprising 175 health care providers and 16,275 diabetic patients. At the end of a 2-year period, the proportion of diabetic patients with HbA1c tested at least once a year rose from 60 to 85%. The percentage of patients with HbA1c <7% rose from 38 to 50%, whereas the percentage with HbA1c >8.5% decreased from 27 to 19%. The number of patients visiting an eye clinic at least once yearly rose from 55 to 65% and of those undergoing microalbumin testing from 27 to 37%. There was a 20% increase in the number of patients with low-density lipoprotein cholesterol measurements. Our study demonstrates the efficacy of diabetes education when directed simultaneously to health care providers and diabetic patients. The improvement in quality of care induced by such intervention can translate into better metabolic control and, ultimately, the prevention of diabetes complications.