Clinical experience of patients is an additional source of information that can inform prescribing decisions for new therapies in practice. In diabetes, for example, patients with recurrent hypoglycemia may be excluded from trials conducted for regulatory purposes. Using insulin degludec (IDeg), a new basal insulin with an ultra-long duration of action as an example, an interim analysis is presented describing whether the decision to prescribe IDeg to patients experiencing treatment-limiting problems on their existing insulin regimes represented good clinical and economic value.