Ninety 11-16 year olds with T1DM (duration >1 year), attending paediatric diabetes outpatient clinics based in 4 centres in South-West England, UK, will be recruited to a randomised controlled trial of one to one sessions of CBT versus non-directive supportive counselling. Participants will attend up to 6 sessions (weekly) with either a CBT therapist or a counsellor, with 2 further sessions at 6 and 12 months. Follow up will continue for 12 months post intervention. HbA1c is the primary outcome measure. Psychological measures will also be measured.