OBJECTIVES:  To examine the association between body mass index (BMI) categories, poor hemoglobin A1c control (HbA1c≥7%), and healthcare expenditures among US patients with type 2 diabetes mellitus (T2DM) and BMI classified as overweight or greater (BMI ≥25). METHODS:  Retrospective, observational study using U.S. electronic medical records linked to administrative claims data (Optum’s Integrated Claims-Clinical data). Patients selected for study were aged≥18, had a recorded BMI between 25-80 during 2014, were continuously enrolled in health insurance for 6 months before and after the last BMI measurement (12-month evaluation period) in 2014, and had ≥1 medical claim T2DM diagnosis and ≥1 antihyperglycemic prescription claim within the evaluation period. Patients were classified into BMI categories using the last recorded BMI in 2014: 25-29.9 (overweight); 30-34.9 (obese/class-I [OCI]); 35-39.9 (obese/class-II [OCII]); ≥40 (obese/class-III [OCIII]). Multivariable regressions adjusting for patient demographics were used to examine the associations between poor HbA1c control, BMI category, and separate outcomes of total healthcare expenditures and pharmacy expenditures measured during the evaluation period. RESULTS:  A total of 27,117 patients were included for study (mean age=64; 52% female): Compared to patients with HbA1c<7%, those with HbA1c≥7% had 8% higher total healthcare expenditures (Cost Ratio [CR]=1.08, P=0.002, adjusted=$22,477 vs. $20,837) and 23% higher pharmacy expenditures (CR=1.23, P<0.001, adjusted=$5,297 vs. $4,297). Compared with overweight patients: OCI patients did not have significantly higher total healthcare or pharmacy expenditures; OCII patients did not have significantly higher total healthcare expenditures but did have 17% higher pharmacy expenditures (CR=1.17, P<0.001, adjusted=$5,287 vs. $4,527); OCIII patients had 13% higher total healthcare expenditures (CR=1.13, P=0.001, adjusted=$24,206 vs. $21,433) and 30% higher pharmacy expenditures (CR=1.30, P<0.001, adjusted=$5,895 vs. $4,527). CONCLUSIONS:  Among patients with T2DM who are overweight or obese, poor HbA1c control and high levels of obesity are associated with higher total healthcare expenditures and pharmacy expenditures.