Response to Comment on: Morden et al. Further Exploration of the Relationship Between Insulin Glargine and Incident Cancer: A Retrospective Cohort Study of Older Medicare Patients. Diabetes Care 2011;34:1965-1971

We appreciate the discussion initiated by Badrick et al. (1) and thank them for the questions raised. In an ideal world, we would have a randomized trial with the enormous sample necessary to answer this question as well as decades of follow-up. In an imperfect world, our analysis reveals the experience of a significant fraction of U.S. patients with diabetes using insulin glargine over 3 years of observation.Regarding our prevalent users cohort and fixed treatment group assignment, we acknowledged the reasonable but unproven assumption that our observed exposure reflects unobserved exposure, preceding 2006 (Part D inception). Under this assumption, assignment to treatment observed in the earliest observation window is the best exposure …