OBJECTIVES: To assess clinical and resource utilization outcomes between elderly type 2 diabetes patients  initiating basal insulin analog administered via pens vs. vials.   METHODS: An online survey of 352 U.S. primary care physicians was used to collect retrospective patient chart data on 500 elderly type 2 diabetes patients who initiated on basal insulin analog in 2009. Information on glycemic control, severe hypoglycemic events, and diabetes-related healthcare resource utilization was collected prior to initiation and over a 12-month study period following insulin initiation.  Information on adherence, both objective (measured via proportion of days covered [PDC]) and physician-revised (based on a revision of the objective PDC) was also collected for the study period. Multivariate regression analyses were used to control for confounding factors. RESULTS: Over the study period, initiation on pens, compared to vials, was associated with HbA1c levels 0.14 points lower (P=0.027).  No differences were seen in the likelihood of reaching an HbA1c thresholds of 7% (hazard ratio [HR]=1.05, P=0.738), though the likelihood was 27% and 55% higher for pen initiators for HbA1c thresholds of 7.5% (HR=1.27, P=0.041) and 8% (HR=1.55, P<0.001), respectively.  Rates of severe hypoglycemic events, inpatient, outpatient, and endocrinologist visits were similar between cohorts, but rates of emergency room visits were 68% lower for the pen cohort (IRR=0.32, P=0.017).  No significant differences in objective adherence rates (PDC) were observed (P=0.080), while physician-revised adherence levels indicated a 2.2 percentage point higher adherence level for the pen cohort (P=0.034). CONCLUSIONS: Results from this study suggest that initiation on insulin pens, as compared to vials, may be associated with better glycemic control, fewer emergency room visits, and higher adherence levels (based on physician assessments) without an impact to the incidence of severe hypoglycemic events.  Objective adherence and other resource utilization categories were not significantly different between the two cohorts.