Eligible subjects with an HbA1c equal to or above 7% at end of treatment in NN1250-3643 (NCT01193309) trial will be randomised to receive treatment intensification while subjects with an HbA1c below 7% at end of treatment in NN1250-3643 (NCT01193309) may continue to receive insulin degludec treatment. Subjects are to continue their pre-trial metformin treatment.