This study is designed to collect 3-axis accelerometry data and heart rate data during a variety of different home activities, as well as during formal exercise, both aerobic exercise (on a calibrated treadmill) and resistance exercise (straight-leg raises or equivalent), in healthy subjects as well as subjects with type 1 diabetes. Optionally VO2 data from a portable VO2 mask will be obtained. The data collected will be used to further enhance our algorithm that, in future closed-loop studies, will detect exercise and automatically trigger algorithmic adjustments to reduce exercise-related hypoglycemia during and after exercise in individuals with type 1 diabetes.