Objective: To assess differences in overall and diabetes-related cost and utilization between diabetes patients treated with insulin detemir and insulin glargine. Methods: Retrospective data analysis included commercial enrollees in a large US health plan with medical and pharmacy benefits. Patients were identified if their first prescription claim (index) for insulin detemir or insulin glargine occurred between May 1, 2006 and December 31, 2006. Eligible patients were required to have 6 months of continuous enrollment pre- and post-index date, no evidence of insulin detemir or insulin glargine use during pre-index and an A1C reading during the pre-index period. Primary outcomes include daily average consumption (DACON) of insulin detemir or insulin glargine and overall and diabetes-related cost. Differences in outcomes between insulin detemir and insulin glargine users were adjusted for baseline characteristics through generalized linear modeling (GLM). Propensity score matching was used to reduce selection bias between the two groups. Results: There were 153 insulin detemir and 640 insulin glargine patients in the study, with no significant difference in age, gender and diabetes types between the two groups. Adjusted DACON for insulin detemir users was 34.3 units/day compared to 32.9 units/day for insulin glargine (p=0.51). Adjusted diabetes-related pharmacy cost for insulin detemir users was higher than insulin glargine patients ($1467 vs. $1255; p<0.01). However, adjusted diabetes-related medical cost for insulin glargine users was more than twice that of insulin detemir users ($2304 vs. $1091; p<0.01). Moreover, adjusted overall medical cost for insulin glargine users was also much higher compared to insulin detemir patients ($7497 vs. $6221; p<0.05). No difference in overall pharmacy cost was observed. Conclusion: No significant difference in DACON between insulin detemir and insulin glargine users was observed. Although insulin detemir patients pay more for diabetes-related prescription medications, these costs were more than offset by significantly lower diabetes-related and overall medical costs.