Objective - To describe self-reported treatment adherence among people with type 2 diabetes (T2D) treated with insulin and/or oral antidiabetic drugs (OADs) and to identify the factors influencing it. Patients and Methods - A total of 8,926 people with diabetes were randomly selected from among beneficiaries of the General Scheme for Salaried Workers and the Social Scheme for the Self-Employed, residing in metropolitan France, aged 18 or older as of July 31, 2007, and who had received at least three reimbursements for OADs and/or insulin during the previous 12 months. A self-administered questionnaire was sent to all randomly selected individuals, and treatment adherence was assessed using 6 validated questions. The response rate to the self-administered questionnaire was 48%, with 4,277 questionnaires returned. A polytomous logistic regression was used to identify the determinants of treatment adherence, taking into account the sampling design and non-response (weighting). Results - Treatment adherence was studied in 3,637 patients with type 2 diabetes (T2D), with a mean age of 66 years (range 18–102) and 54% men. Treatment adherence was good in 39% of cases, moderate in 49%, and poor in 12%. In multivariate analysis, factors associated with poor adherence were, in descending order of importance, age < 45 years (OR = 5.2; 95% CI [2.7–10.1]), difficulties managing medication intake (OR = 3.8; 95% CI [2.2–6.9]), a doctor-patient relationship in which the patient reported making decisions alone (OR = 3.3; 95% CI [2.1–5.0]), and the implementation of diabetes management recommendations perceived as too burdensome (OR = 2.7; 95% CI [1.6–4.6]), non-European geographic origin (OR = 2.6; 95% CI [1.8–3.9]), a lack of family or social support (OR = 2.5; 95% CI [1.7–3.6]), a perceived need for information on diabetes management (OR = 2.0; 95% CI [1.4–2.7]), financial difficulties (OR = 1.7; 95% CI [1.2–2.4]), concern about the future with diabetes (OR = 1.6; 95% CI [1.2–2.2]), and a perceived need for educational support in addition to routine medical care for diabetes (OR = 1.6; 95% CI [1.2–2.1]). Conclusion - This analysis characterizes treatment adherence among patients with type 2 diabetes at the national level. Understanding the determinants of treatment adherence can help tailor care for patients most likely to have poor adherence. Paper cited in the journal "Diabetes and Metabolism" in Supplement 1, Volume 36.