Exercise in people with type 1 diabetes (T1DM) can produce large changes in blood glucose, with hypo- and hyperglycaemia before and following exercise. Different exercise types, intensity and duration have significantly different effects on blood glucose control, and on the endocrine response to exercise. Exercise performance can also be impaired in T1DM. There have been significant recent improvements in the knowledge of what underlies these changes and in the appropriate management to support the maintenance of euglycaemia. Further advances in insulin infusion pump therapy and continuous subcutaneous glucose monitoring are likely to be useful in the management of people with T1DM who want to exercise.