We attempted to determine the percentage of patients meeting Health Plan Employer Data Information Set (HEDIS) criteria for blood pressure control (< or = 140/90 mm Hg), to identify factors contributing to differences in blood pressure control among those who met HEDIS criteria and those who did not, and to assess compliance with blood pressure management recommendations established by the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure (JNC-VI) for diabetes mellitus and myocardial infarction. In this retrospective analysis, we randomly selected 502 patient records from three primary care clinics in southeast Michigan. All patients were commercial members of one health maintenance organization, 74% of whom met HEDIS criteria for blood pressure control. These patients took fewer blood pressure drugs throughout the year (p=0.023) and had lower antihypertensive drug costs than those who did not achieve HEDIS blood pressure goals (p=0.016). According to JNC-VI criteria, 46% of diabetic patients were at their blood pressure goal of below 130/85 mm Hg and 71.6% were managed with angiotensin-converting enzyme inhibitors or angiotensin receptor blockers. Eighty-five percent of patients were taking beta-blockers after myocardial infarction. The percentage of patients achieving target blood pressure exceeded the national average and was associated with few antihypertensive drugs and low drug cost. Effective and appropriate management of blood pressure in people with diabetes remains a challenge.