Exercise is a significant physiological challenge with markedly increased cardiac output, respiration and fuel mobilisation. Whilst the cardio-respiratory response to exercise is similar in type 1 diabetes to that seen in non-diabetic subjects, the response to mobilisation of fuel source to support exercise is impaired. This effect, when combined with the difficulties of nutrition and insulin therapy in type 1 diabetes may negatively impact on the performance of the athlete with diabetes. Hypoglycaemia both during and following exercise, is a significant risk. Furthermore, hyperglycaemia prior to and following some types of exercises can also be problematic. The effect on blood glucose of varying sports can be predicted, and therefore, pro-active adjustments of insulin therapy and nutrition can be made. This article outlines the important differences seen with exercise in type 1 diabetes and discusses appropriate strategies to normalise performance and reduce the risk of hypoglycaemia.