The STAK programme promotes physical activity in children who have a chronic condition, low levels of physical activity, are overweight or who lack confidence to take part in physical activity. The intervention involves an Activity Diary, circuit training, pedometer step counting, daily physical activity monitoring and goal setting to promote long-term increases in physical activity and its associated health benefits. This randomised single-centre feasibility study will test whether the STAK programme is feasible for children with T1DM, in terms of acceptability, attractiveness and compliance and a qualitative process evaluation will aid the assessment of feasibility.