To examine the relationships between daily energy expenditure, energy intake and glycemic control in young adults with type 1 diabetes.Cross-sectional study.Energy expenditure (kcalkg −1 d −1 ) and duration of participation in physical activity were measured from a 3-d activity diary and categorized according to their intensity on a 1–9 scale. Energy intake was measured by a 3-d food record. Glycemic control was measured using the HbA 1c .Energy expenditure and intake were assessed in 35 young adults with type 1 diabetes (age: 28±7 years). Participants with higher energy expenditure from moderate to intense physical activity (categories 6–9) presented higher proportion of energy intake derived from carbohydrate and lower proportion of lipids in the diet with significantly higher HbA 1c values (7.3±1.0% vs 6.7±0.6%).These results suggest that highly physically active individuals with type 1 diabetes consume more carbohydrates than lipids, a strategy that may affect their glycemic control. Further studies are needed to develop interventions to improve glycemic control in highly active individuals with type 1 diabetes.