OBJECTIVES: To examine changes in health and lifestyle indicators over 6 months in persons with type 2 diabetes mellitus receiving nutrition counseling from a registered dietitian, and to promote dietetics professionals' participation in outcomes monitoring and research. DESIGN: Prospective, noncontrolled descriptive study. SUBJECTS: Two hundred forty-four physician-referred adults with type 2 diabetes mellitus from 31 sites who received usual and customary nutrition counseling, and 83 registered dietitians. MAIN OUTCOME MEASURES: Glycemic control, coronary heart disease risk, self-management behaviors, and quality of life were measured at baseline, 3 months, and 6 months. Dietitians' perceptions of the study were also measured. STATISTICAL ANALYSIS: Repeated-measures analysis of variance, paired t test, Wilcoxon signed rank test, sign test, Spearman correlation, and chi 2 analysis were conducted. RESULTS: Weight and glycemic control, coronary heart disease risk, and self-management behaviors improved significantly between baseline and 3 months and baseline and 6 months. Weight, body mass index, and glycosylated hemoglobin value also improved significantly between 3 months and 6 months. Increased time and/or number of sessions with the registered dietitian were associated with weight loss and reduced glycosylated hemoglobin, fasting plasma glucose, total cholesterol, and triglyceride levels. Self-perceived health status and missed workdays were significantly improved at 6 months. Difficulty obtaining current laboratory values, lack of time, and inability to reach subjects for follow-up presented the greatest obstacles for the dietitians. CONCLUSIONS: Positive outcomes were observed in adults receiving nutrition intervention for type 2 diabetes. Clinical improvements were greatest between baseline and 3 months, with stabilization between 3 months and 6 months, suggesting ongoing intervention is needed to support continued clinical progress. Dietitians found participation in this state affiliate-coordinated research project rewarding.