Patients will be assigned to receive insulin detemir once daily before breakfast. Short acting insulin analog , Novorapid, will be used for mealtime insulin. The starting dose of insulin detemir will be individually determined. Based on self-measured fasting blood glucose levels, insulin doses will be titrated throughout the trial, aiming at pre breakfast and premeal concentrations of 90-180 mg/dl for subjects aged 6-12 years and 80-130 mg/dl for subjects aged 13-18 years.