The objective of the study was to determine the effectiveness and cost-effectiveness of primary care and community-oriented interventions in managing HbA1c, blood pressure, and lipids, and reducing hospitalizations and emergency room visits over 2 years. We describe an ongoing, randomized controlled trial of 542 urban African-Americans with type 2 diabetes ages 25 years and older who are members of a university-affiliated managed-care organization in Baltimore, MD. The participants are 74% female, have a mean age of 58 years, and 35% have yearly incomes greater than 7500 US dollars. Participants were randomized to one of two intervention groups for a period of 2 years: (1) usual medical care plus minimal telephone intervention implemented by a trained lay health educator (control group) or (2) usual medical care plus intensive intervention implemented by a nurse case manager (NCM)/community health worker (CHW) team. The intensive NCM/CHW team executes individual plans of care using evidence-based algorithms that focus on traditional diabetes self-management, screening and management of diabetes-related complications, and social issues surrounding diabetes care. Face-to-face NCM visits are conducted in the clinic once per year and CHW visits are conducted in the participant's home one to three times per year, both with additional follow-up contacts as needed. Written and verbal feedback (when necessary) is provided to the participant's primary care physician. All participants are expected to attend a 24-month follow-up visit where data are collected by interviewers blinded to intervention assignment. As of May 1, 2003, recruitment is complete, interventions are being fully implemented, and 24-month follow-up visits are beginning. Baseline sociodemographic characteristics, health-care utilization, health behaviors, and clinical characteristics of the study population are reported. This study is designed to test the hypothesis that a primary-care-based NCM plus CHW team approach is an effective, practical, and economically feasible strategy for translating current knowledge about type 2 diabetes into high-quality health care for urban African-Americans.