Purpose: To investigate the association between physician participants levels of engagement in a Web-based educational intervention and their patients baseline diabetes measures. Method: The authors conducted a randomized trial of online CME activities designed to improve diabetes care provided by family, general, and internal medicine physicians in rural areas of 11 southeastern states between September 2006 and July 2008. Using incidence rate ratios derived from negative binomial models, the relationship between physicians engagement with the study Web site and baseline proportion of their patients having controlled diabetes (hemoglobin A1c ≤7%) was explored. Results: One hundred thirty-three participants (intervention = 64; control = 69) provided information for 1,637 patients with diabetes. In the intervention group, physicians in practices in the worst quartiles of A1c control were least engaged with the study Web site in nearly all dimensions. Total number of pages viewed decreased as quartile of A1c control worsened (137, 73, 68, 57; P = .007); similarly, for a given 10% increase in proportion of patients with controlled A1c, participants viewed 1.13 times more pages (95% CI: 1.02-1.26, P = .02). In the control group, engagement was neither correlated with A1c control nor different across quartiles of A1c control. Conclusions: Engagement in Web-based interventions is measurable and has important implications for research and education. Because physicians of patients with the greatest need for improvement in A1c control may not use online educational resources as intensely as others, other strategies may be necessary to engage these physicians in professional development activities. Copyrite © by the Association of Amarican Medical Colleges.