OBJECTIVE: Although suboptimal glycemic control is known to be common in diabetic adults, few studies have evaluated factors at the level of the physician-patient encounter. Our objective was to identify novel visit-based factors associated with intensification of oral diabetes medications in diabetic adults. RESEARCH DESIGN AND METHODS: We conducted a nonconcurrent prospective cohort study of 121 patients with type 2 diabetes and hyperglycemia (A1C > or =8%) enrolled in an academically affiliated managed-care program. Over a 24-month interval (1999-2001), we identified 574 hyperglycemic visits. We measured treatment intensification and factors associated with intensification at each visit. RESULTS: Provider-patient dyads intensified oral diabetes treatment in only 128 (22%) of 574 hyperglycemic visits. As expected, worse glycemia was an important predictor of intensification. Treatment was more likely to be intensified for patients with visits that were "routine" (odds ratio [OR] 2.55 [95% CI 1.49-4.38]), for patients taking two or more oral diabetes drugs (2.82 [1.74-4.56]), or for patients with longer intervals between visits (OR per 30 days 1.05 [1.00-1.10]). In contrast, patients with less recent A1C measurements (OR >30 days before the visit 0.53 [0.34-0.85]), patients with a higher number of prior visits (OR per prior visit 0.94 [0.88-1.00]), and African American patients (0.59 [0.35-1.00]) were less likely to have treatment intensified. CONCLUSIONS: Failure to intensify oral diabetes treatment is common in diabetes care. Quality improvement measures in type 2 diabetes should focus on overcoming inertia, improving continuity of care, and reducing racial disparities.