Insulin degludec has been extensively studied in the BEGIN programme in a range of patients with type 1 or type 2 diabetes. The programme includes insulin-naive type 2 diabetes, insulin-treated type 2 and type 1 diabetes which are investigated as basal-bolus therapy, basal plus oral therapy, and basal vs. oral therapy and also the flexible dosing options. In all insulin degludec phase 3 trials, the efficacy of once daily insulin degludec was established, as insulin degludec being non-inferior to comparators in reducing HbA(1c). Also the flexible dosing option is an attractive feature of this insulin that mightimprove adherence to therapy and conceivably improve outcomes.