OBJECTIVES: Since 2008, the Caisse Nationale d'Assurance Maladie des Travailleurs Salariés has set up a diabetic patient support programme in ten pilot departments in France. In addition to written advice, programme members also have access to telephone support from health education nurses. In 2010, the sophia programme was extended to another nine departments and, at the beginning of 2013, it was generalized to all French departments. The present study evaluated the health economics impact of the programme after a follow-up of 3 years. This analysis follows a preliminary assessment that demonstrated positive results after 1 year. METHODS: The variation of various healthcare use indicators as well as outpatient and inpatient costs was compared between three cohorts: members of pilot departments, non-members, and a control group of diabetic patients living in departments in which sophia was not available. Results are adjusted for between-group differences observed at the beginning of the programme. RESULTS: Adjusted analysis showed that, after matching for all other characteristics, compliance with recommended examinations improved to a much greater extent among programme members than among control subjects and non-members. Although all healthcare costs continued to increase in each cohort, outpatient and inpatient expenditure was €226 lower for programme members than for controls for the period 2009-2011: -€54 for outpatient care and -€172 for inpatient care. Although the outpatient expenditure of programme members was higher (+€40) for outpatient visits and medical procedures, their paramedical expenditure was lower (-€89). Hospitalization rates for diabetes were significantly lower among members than among controls. CONCLUSIONS: These results confirm the significant impact of the sophia programme on compliance with clinical practice guidelines in diabetology, hospitalization rates, and the 3-year growth of outpatient and inpatient costs. An assessment of the impact of the sophia programme on clinical parameters will be conducted in the near future.