CMAJ OPEN, 5(2) E359I nterpersonal continuity of care refers to the ongoing relationship between a patient and an individual physician. 1 There is good evidence from a systematic review that a high level of interpersonal continuity of care is associated with decreased hospital admissions and emergency department visits, and improved patient satisfaction.2 To what extent a high level of continuity of care is associated with a higher likelihood of medication adherence is less clear.2 Medication adherence consists of 2 main constructs: persistence (consistently refilling prescriptions for the prescribed length of time) and compliance (taking the drug in accordance with the prescribed dosage and schedule).3 To our knowledge, the relation between interpersonal continuity of care and medication adherence has been assessed in 6 studies. [4][5][6][7][8][9] In 4 of these studies, 4,7-9 a positive relation was observed. For example, a high level of continuity of care was associated with higher persistence with statins 8 and higher compliance with treatment with orally administered antidiabetics, 7 statins 9 and drugs used in heart failure.4 However, 5 of these studies 4,6-9 were limited by the fact that their design was cross-sectional. Therefore, the temporal relation between continuity of care and medication adherence could not be established.Patient adherence to oral antidiabetic treatment is not optimal. For example, in a study conducted in Quebec, 79% of patients were persistent with oral antidiabetic treatment 1 year after initiation of therapy; of the 79%, only 78% were compliant (obtained drug supplies for at least 80% of days during the year). Background: Prior studies have shown that, compared to patients with a low level of interpersonal continuity of care, patients with a high level of continuity of care have a lower likelihood of hospital admission and emergency department visits, and a higher likelihood of patient satisfaction. We sought to determine whether higher levels of continuity of care are associated with medication persistence and compliance among new users of oral antidiabetic treatment.