This randomized trial tested the hypothesis that a telephone contact with a patient recently prescribed a new medication for uncontrolled glycated hemoglobin (A1c), blood pressure, or low-density lipoprotein cholesterol would improve (a) primary medication adherence, (b) medication persistence, (c) medication possession ratio, and (d) A1c, blood pressure or low-density lipoprotein cholesterol control. This study was part of the larger Agency for Healthcare Research and Quality funded SUPREME-DM study. The clinical trial reported here was coordinated and led by HealthPartners Institute for Education and Research, while data collection was coordinated through Kaiser Permanente Northwest and analysis was conducted at Kaiser Permanente Colorado. The clinical intervention sites for this study included Kaiser Permanente Northern California, Group Health Cooperative, Marshfield Clinic, and Geisinger Clinic.