OBJECTIVES: Persistence with respect to injectable therapy in type 2 diabetes is known to impose a challenge to patients. One potential explanation is aversion to injection and risk of hypoglycemic events. Insulin analogues have shown in clinical trials to reduce the risk of hypoglycemic events versus human insulins, and insulin injection using a pen device is generally perceived as less burdensome than administration via vial and syringe.  METHODS: This retrospective data analysis compared persistence between two types of basal insulin and administration: Neutral protamine hagedorn, NPH, administered by vial and syringe and insulin detemir, IDet, administered by FlexPen®. Data were derived from healthcare claims between 2004 and 2009 from a large national US payer and included type 2 diabetes patients that initiated either IDet FlexPen® or NPH in vials without any prescription fills for any insulin in the previous 12 months. Patients were defined as being persistent to therapy as long as they filled their prescription within the 80th percentile of days between fills adjusted to reflect differences in pack sizes. RESULTS: The IDet FlexPen® cohort (n=1082) and the NPH vial cohort (n=794) were of similar age (54.06 vs. 53.13, p=0.134), but IDet FlexPen® had a lower proportion of female patients than NPH vials (44% vs. 55%, p<0.001) and fewer treatment naïve patients (no pre-index OADs) (9% vs 45%, p<.001). Persistency to therapy at 12 months after initiation was 23% and 13% (p<0.001) for IDet FlexPen® and NPH vials, respectively. Average days of persistence was 167 days for the IDet FlexPen® cohort and 123 days for NPH vials (p<0.001). CONCLUSIONS: Persistence to insulin therapy among type 2 diabetes patients could be improved. This study suggests that insulin persistency may be improved by initiating insulin using therapies associated with lower risk of hypoglycemic events and administering it in a pen.