OBJECTIVES: This study examined the demographics, comorbidities, clinical characteristics, and treatments of people with type 2 diabetes mellitus (T2DM) treated with metformin and sulfonylurea as well as an elderly subgroup. Achievement of predefined quality measure goals (glycated hemoglobin [A1C], blood pressure [BP], low-density lipoprotein cholesterol [LDL-C], body mass index [BMI]) and their association with diabetes-related healthcare costs were assessed. STUDY DESIGN: The study applied a retrospective longitudinal cohort design. METHODS: Health insurance claims and electronic medical records from 14,532 adults with T2DM (2007- 2011) were used to identify a sample receiving metformin and sulfonylurea (MET+SU) concomitantly. The index date was the first dispensing of MET+SU after 6 months of eligibility. Clinical characteristics were assessed during baseline. Quality measure attainment (A1C < 8%, BP < 140/90 mm Hg, LDL-C level < 100 mg/dL, BMI < 30 kg/m(2)), was evaluated during the 12 months following the index date. Association between attainment and diabetes-related costs was evaluated using non-parametric bootstrap methods adjusting for imbalance in baseline characteristics between cohorts. RESULTS: Among 2044 patients, including 1283 patients 65 years and older, hyperlipidemia, hypertension, and cardiovascular disease were the most common baseline comorbidities. Quality measure goal attainment was 63.9% for A1C, 33.1% for BP, 68.2% for LDL-C level, and 34.4% for BMI, and was associated with significantly lower diabetes-related costs per patient per year compared with nonattainment (adjusted mean cost differences: -$1445 for A1C; -$1218 for BMI; -$2029 for A1C and BMI; -$2073 for A1C, BMI, and BP; all P < .05). CONCLUSION: This study highlights the high incidence of comorbidities and potential financial implications of attaining T2DM quality outcomes.