AIMS: To compare glycemic outcomes in adults with type 2 diabetes mellitus (T2DM) before and 90 days after initiating Omnipod® or Omnipod DASH® Insulin Management Systems. METHODS: In this retrospective observational study (N = 3,592) change in HbA1c level, total daily dose (TDD) of insulin (n = 3,053), and frequency of self-reported hypoglycemic events (HE, <70 mg/dL, n = 2,922) were assessed overall and by prior treatment modality (multiple daily injections (MDI) or continuous subcutaneous insulin infusion (CSII)), age group, and baseline HbA1c category. RESULTS: Change (mean ± SD) in HbA1c was -1.3 ± 1.7% [-14 ± 19 mmol/mol] overall, -1.4 ± 1.7% [-15 ± 19 mmol/mol] for prior MDI users, and -0.9 ± 1.5% [-10 ± 16 mmol/mol] for prior CSII users (p<0.0001). The percentage of patients with HbA1c ≥9% [≥75 mmol/mol] decreased (49% to 19%), and with HbA1c <7% [<53 mmol/mol] increased (10% to 22%) (p<0.0001). Prior therapy, age, and baseline HbA1c category were factors affecting change in HbA1c (p<0.05). Reductions in TDD (overall, -33 ± 52U, p<0.0001) and HE per week (overall, -0.5 ± 2.0, p<0.0001), were seen regardless of prior treatment, age, or baseline HbA1c. CONCLUSIONS: Omnipod System use was associated with statistically and clinically meaningful reductions in HbA1c, TDD, and HE compared to prior treatments in T2DM.