OBJECTIVES: Clinical evidence evaluating polypharmacy and health care utilization with the use of continuous subcutaneous insulin infusion (CSII) in persons with uncontrolled Type 2 diabetes is limited. This study provides a real-world (retrospective) evaluation of the impact of CSII among 973 patients with Type 2 diabetes initiating CSII therapy between January 2005 – October 2007 (mean age 48 years, 47% male, mean duration of follow-up 17 months).  We hypothesized that CSII therapy would reduce rates of polypharmacy (multiple diabetes medication use), ER visits, and hospitalizations.  METHODS: Administrative claims from a large, geographically diverse, US health plan were used.  RESULTS: More than 1/3 of subjects taking oral anti-diabetic medications (OADs) before CSII initiation discontinued oral therapy altogether once they began CSII.  The mean number of OADs used by subjects decreased by 0.67 OADs (1.45 OADs before vs. 0.78 OADs after, p<0.001) after CSII initiation.  The number of subjects using multiple OADs decreased by 58% (40% before vs. 17% after, p<0.001) and rates of switching or augmenting oral therapy decreased from 44% to 25% (p<0.001) from baseline to follow-up. The rate of ambulatory visits increased from pre- to post-CSII initiation (1.80 visits/subject/month before vs. 2.01 visits/subject/month after CSII initiation, p<0.01), likely reflecting increased use of diabetes education services related to CSII.  However, the rates of ER visits (0.11 visits/subject/month before vs. 0.08 visits/subject/month after, p<0.01) and hospitalizations (0.03 visits/subject/month before vs. 0.01 visits/subject/month after, p<0.01) significantly decreased after CSII initiation. CONCLUSIONS: Insulin pump therapy (CSII) was associated with significant decreases in polypharmacy and medication changes.  Also, CSII may lead to a reduction in health care utilization as indicated by reductions in rates of ER visits and hospitalizations.