OBJECTIVE: To evaluate antidiabetic drug treatment patterns and glycemic control among patients diagnosed with type 2 diabetes mellitus. STUDY DESIGN: Retrospective study using the automated databases of a 200 000-member HMO. METHODS: The study population consisted of patients > or =18 years of age with documented type 2 diabetes mellitus from January 1, 2002, through December 31, 2002. We determined the proportion of patients who had optimal glycemic control (glycosylated hemoglobin <7%) during the 6 months after the initial documentation of diabetes during calendar year 2002 (index date). RESULTS: Of the 4282 patients who met the inclusion criteria, 1050 (25%) received 1 oral agent, 486 (11%) received 2 oral agents, 56 (1%) received > or =3 oral agents, 84 (2%) received insulin and an oral agent, and 107 (2%) received insulin exclusively within 90 days after the index date. Among the 1075 patients receiving antidiabetic drug therapy who had a laboratory test result documented, 414 (39%) had optimal glycemic control. Optimal control was most frequent among patients receiving 1 oral agent (47%) and least frequent among patients receiving > or =3 oral agents (13%) (P <.01). Patients with a prior history of suboptimal glycemic control were less likely to have optimal glycemic control. CONCLUSIONS: Multiple oral antidiabetic agents may serve as a marker for more severe, uncontrolled diabetes. The vast majority of patients treated with multiple oral antidiabetic agents had suboptimal glycemic control, suggesting a need for intensified efforts to treat this particular group of patients to recommended goal levels.