This trial is conducted globally. The aim of the trial is to investigate the efficacy and safety of insulin detemir versus insulin Neutral Protamine Hagedorn (NPH) in combination with the maximum tolerated dose of metformin and diet/exercise on glycaemic control in children and adolescents with type 2 diabetes insufficiently controlled on the maximum tolerated dose of metformin with or without other oral antidiabetic drug(s) with or without basal insulin.