Health information technology shows promise for improving chronic disease care. This study assessed the impact of a diabetes management form (DMF), accessible within an electronic health record. From 2007 to 2009, 2108 diabetes patients were seen in 20 primary care practices; 1103 visits involved use of the DMF in 2008. The primary outcome was optimal care: HbA1c 8%, low-density lipoprotein (LDL) cholesterol <100 mg/dL, blood pressure <130/80 mm Hg, not smoking, and aspirin prescription in patients 40 years. After adjusting for number of visits, age, sex, and insulin use, DMF-exposed patients showed less improvement in attaining optimal care (estimated difference-in-difference [DID] = -2.06 percentage points; P < .001), LDL cholesterol (DID = -2.30; P = .023), blood pressure (DID = -3.05; P < .001), and total cholesterol (DID = -0.47; P = .004) targets. Documented microalbumin tests, aspirin prescription, and eye and foot exams increased more. Thus, DMF use was associated with smaller gains in achieving evidence-based targets, but greater improvement in documented delivery of care.